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Interventions to promote informed consent for patients undergoing surgical and other invasive healthcare procedures

  1. Paul Kinnersley1,*,
  2. Katie Phillips1,
  3. Katherine Savage1,
  4. Mark J Kelly2,
  5. Elinor Farrell1,
  6. Ben Morgan1,
  7. Robert Whistance3,
  8. Vicky Lewis4,
  9. Mala K Mann5,
  10. Bethan L Stephens1,
  11. Jane Blazeby6,
  12. Glyn Elwyn1,
  13. Adrian GK Edwards1

Editorial Group: Cochrane Consumers and Communication Group

Published Online: 6 JUL 2013

Assessed as up-to-date: 17 JUL 2012

DOI: 10.1002/14651858.CD009445.pub2


How to Cite

Kinnersley P, Phillips K, Savage K, Kelly MJ, Farrell E, Morgan B, Whistance R, Lewis V, Mann MK, Stephens BL, Blazeby J, Elwyn G, Edwards AGK. Interventions to promote informed consent for patients undergoing surgical and other invasive healthcare procedures. Cochrane Database of Systematic Reviews 2013, Issue 7. Art. No.: CD009445. DOI: 10.1002/14651858.CD009445.pub2.

Author Information

  1. 1

    Cardiff University, Cochrane Institute of Primary Care and Public Health, School of Medicine, Cardiff, Wales, UK

  2. 2

    Cardiff University, South East Wales Trials Unit, Institute of Translation, Innovation, Methodology and Engagement, Cardiff, Wales, UK

  3. 3

    University of Bristol, Academic Unit of Surgical Research, School of Social and Community Medicine, Bristol, UK

  4. 4

    Wales Deanery for Postgraduate Medical and Dental Education, Cardiff, Wales, UK

  5. 5

    Information Services, Cardiff University, Support Unit for Research Evidence (SURE), Cardiff, Wales, UK

  6. 6

    University of Bristol, Section of Healthcare Research, The School of Social and Community Medicine, Bristol, UK

*Paul Kinnersley, Cochrane Institute of Primary Care and Public Health, School of Medicine, Cardiff University, 3rd Floor, Neuadd Meirionnydd, Heath Park, Cardiff, Wales, CF14 4XN, UK. kinnersley@cf.ac.uk.

Publication History

  1. Publication Status: New
  2. Published Online: 6 JUL 2013

SEARCH

 

Background

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. Contributions of authors
  12. Declarations of interest
  13. Sources of support
  14. Differences between protocol and review
  15. Index terms
 

Description of the condition

Before many healthcare procedures can be undertaken, there is an accepted legal and ethical principle that a suitably-trained clinician must obtain informed consent from the patient (or consumer). Obtaining informed consent usually requires a discussion between clinician and patient about a surgical or invasive healthcare intervention which results in the patient understanding what the procedure will involve, the risks and benefits of the procedure and their likelihood, and alternative management options, and then agreeing (or declining) to undergo the procedure.  The process of achieving informed consent may occur as a single event or over a series of encounters and discussions in outpatient clinics or, for inpatients, on hospital wards.  The consent discussion may be supported to a greater or lesser degree by the provision of comprehensive written, video or web-based information. However it is achieved, it is most clearly shown as concluding when the patient signs a consent form.

Patients are usually required to give consent for a procedure because, while the intention of the procedure is to diagnose or improve their health, there is a risk of injury or other negative outcomes. The most common use of consent relates to surgical procedures but it is also important for a range of other interventions to investigate or treat diseases.  Examples include: diagnostic interventions, for example endoscopy, bronchoscopy and angiography; procedures associated with childbirth and pregnancy, for example delivery by caesarean section, amniocentesis or chorionic villous sampling; and curative procedures, for example chemotherapy and radiotherapy. Consent is usually required for all procedures where the patient is under general anaesthetic, although there may not be a requirement to seek consent for the anaesthetic itself. In emergencies, or when the patient is too ill to provide written consent, clinicians are still expected to seek the oral consent of the patient and document this. In such circumstances they may also seek the consent of a relative or other delegate. Clinicians are also required to seek the consent of a relative or delegate if the patient is under 16 years old, or if the patient is not capable of giving informed consent due, for example, to intellectual disability. If it is not possible to seek consent, for example because the patient is unconscious and no relatives or other delegates are available, clinicians are expected to exercise their judgement and act in the patient's best interests. Clinical trials or research procedures require additional consent, by which the patient confirms their agreement to take part in clinical research. This form of consent (consent for research studies) is excluded from this review and is discussed in other reviews (Ryan 2009; Hon 2012).

The signed consent form is frequently used as evidence of informed consent.  However, this is often an oversimplification since there is a risk of acquiescence by a patient who may not be fully informed. For consent to be valid it must be given voluntarily by a patient who has the capacity to consent to the intervention in question and who has done each of the following:

  • Understood the information provided;
  • Retained that information long enough to be able to make the decision;
  • Weighed up the information as part of the decision-making process; and
  • Communicated their decision (DoH 2009).

These requirements for informed consent are supported by Marteau who described a model to measure informed choice with regard to antenatal screening (Marteau 2001). This involves assessing the patient's knowledge, attitudes and behaviour. This model aims to measure the patient's knowledge (for example of antenatal screening), their attitude towards the screening (either positive or negative), and whether their behaviour (uptake or refusal of the test) is consistent with their attitudes.

Regulatory bodies such as the General Medical Council, British Medical Association and Department of Health in the United Kingdom (UK), the American Medical Association and the Australian Medical Council provide guidance for clinicians about the information they should discuss with the patient during the informed consent process (AMA 2009; AMC 2009; BMA 2009; DoH 2001 DoH 2009; GMC 2008). Information that should be discussed includes the intended benefits and risks and their likelihood, and the alternative options including doing nothing. 

There are three standards of disclosure (or information provision) which may be applied when discussing the risks associated with surgical or invasive healthcare procedures:

  • The ‘professional standard’: a physician is to provide information that a physician of good standing in the physician’s community of peers would provide to his or her patient.
  • The ‘reasonable person standard’: a physician is to provide that information that a hypothetical reasonable person in the position of the patient would want to know.
  • The ‘subjective person standard’: a physician is to provide that information that the particular individual patient in question would want to know (Mazur 2009).

Failure to achieve fully-informed consent has led to a number of legal judgements which have clarified the interpretation of consent with particular emphasis on the provision of information. In Chester v Afshar, a UK case concerning the risks associated with spinal surgery, the House of Lords held that a failure to warn a patient of the risk of injury inherent in surgery, however small the probability, denies the patient the chance to make fully-informed decisions (Chester v Afshar 2004; DoH 2009). In the United States, in Canterbury v Spence the appellate court held that ‘every human being of adult years and sound mind has a right to determine what shall be done to their own body' and stated that ‘the nature of the doctor-patient relationship demands that the physician volunteer that information even if the patient does not ask’ (Canterbury v Spence 1972). In Australia, the High Court inRogers v Whitaker found unanimously against a surgeon who was considered to have provided inadequate information. The court stated that it is part of the doctor's duty to disclose 'material' risks. A risk is held to be material if "in the circumstances of the particular case, a reasonable person in the patient's position, if warned of the risk, would be likely to attach significance to it or if the medical practitioner is, or should be aware that the particular patient, if warned of the risk, would be likely to attach significance to it" (Rogers v Whitaker 1992).

These cases indicate that there is a minimum amount of information that the patient needs in order to make an informed choice, although the depth and breadth of this information will vary from procedure to procedure, and some patients will request further details whilst others prefer to have less information. This may require clinicians to give information to patients who have said that they do not want to know more about the planned intervention.

The UK Department of Health emphasises that if the patient has not been given adequate information, or if they do not understand the information, or have not had sufficient opportunity to ask questions, the consent may not be valid even if the patient has signed a consent form.  Conversely, properly informed verbal consent, without a signed consent form, is not a bar to treatment (DoH 2001; DoH 2009).

Problems with consent may occur because clinicians sometimes underestimate or undervalue the information needs of patients (Beisecker 1990).  Alternatively they may overestimate the amount of information they give (Makoul 1995), lack the skills to give information (Jenkins 1999) or use technical language or jargon.  Patients may feel pressured into consenting to a procedure that they have concerns about, or that they have not had adequate opportunity to discuss (Dixon-Woods 2006).  This can be through over-emphasis of the benefits of a particular treatment, shortage of time, the clinician's manner or lack of empowerment on the part of the patient. Patients’ ability to seek further relevant information may also be influenced by how empowered they feel to ask questions, their knowledge of medical care and their physical condition (Akkad 2004). 

A further challenge can involve the clinician translating population-based estimates to an individual risk for that particular patient (Edwards 2002).  Also patients may attach differing significance to different risks and benefits, and their perceptions of them may vary. 

Clinicians may focus upon communicating specific technical risks of negative outcomes when talking to patients about the procedure, for example the risk of wound infection, bowel perforation or death (Barkin 2009; Ergina 2009).  Some of these are of concern to patients, but sometimes this approach overrides consideration of other concerns of greater importance to the particular patient. These may include the consequences of the procedure, for example pain or length of time off work.  The provision of complex information can be even more difficult when caring for a sick patient in an emergency, particularly if the clinician believes the information may add to the patient’s stress (Jefford 2002).

There are also organisational barriers to achieving informed consent. Ideally clinicians will talk to patients some time (at least two or three days) before the intervention or procedure.  This allows the patient time to reflect on the discussion and deliberate on their options.  However, often the signing of the consent form (and thus the formal consent discussion) is delayed until the patient is admitted (or attends as a day case) for the procedure. Then consenting can become a hurried ritual that does not allow the patient enough time to fully consider their decision (Elwyn 2008).

The use of a standardised consent form may add to the ritualised nature of consent discussion by making the process seem repetitive and ritualistic to the clinician.  This can lead to the clinician becoming desensitised to the patient’s fears and concerns, as the clinician may view the treatment as being routine and commonplace (Picano 2004).  Notably, only 41% of patients believe that the use of consent forms made their wishes known, and 46% believe that the primary function of the consent form was to protect the hospital (Akkad 2006).  Any standardisation of the process runs the risk of failing to promote patient autonomy (Habiba 2004).

 

Description of the intervention

Ensuring informed consent presents challenges for both clinicians and healthcare organisations.  Interventions to promote informed consent usually target patients, clinicians, or both.  Interventions for patients generally provide information (ideally evidence based) about the treatment options, associated benefits, harms, probabilities and scientific uncertainties. Where they also encourage the patients to clarify personal values, ask questions and weigh up the pros and cons of choosing surgery (or a procedure), these interventions can be seen to fulfil the definition of 'decision aids' (Stacey 2011). The interventions may involve face to face contact, or online, video, telephone or leaflet-based information.  Interventions for clinicians generally address skills to improve how they share information, or direct them to concise sources of information. Interventions may also be organisational, for example the provision of more time for the patient to consider the procedure and ask questions.

Interventions may be categorised by whom they target (patients or clinicians); the purpose (e.g. general educational, encouraging shared decision making, etc); the format (media used: e.g. electronic, paper) and the timing and method of delivery (e.g. remote patient access at home, access supervised by a clinician).

 

How the intervention might work

Often patients do not fully understand the information provided during the consent process (Brezis 2008). However a clear set of skills for clinicians can be identified which, if used, increases the likelihood that patients will understand and be able to recall complex clinical information.  Furthermore these include specific skills for shared decision making, risk communication and the use of decision aids. Clinicians can be trained in these skills (Silverman 2005).  

Decision aids have been shown to improve patients’ knowledge regarding options, clarify perceptions of risk, reduce decisional conflict, reduce the number of people feeling passive about decision making and decrease the proportion of people remaining undecided (Stacey 2011). Where decision aids address conditions for which procedures requiring consent are among the options, they may promote informed consent through greater knowledge and consistency of personal values or attitudes with an enacted choice (for or against the treatment or procedure).

 

Why it is important to do this review

Over 4 million surgical procedures are undertaken in England each year (Royal College of Surgeons of England 2011), which all require patient consent. Similar volumes of procedures will occur in other similar countries.  In addition there will be considerable numbers of other procedures requiring consent. However, the consent consultation frequently does not meet the needs of the patient (Akkad 2004).  Reports indicate that patients do not receive sufficient information, that the information is not fully understandable or that the information patients receive is not tailored to their particular needs (Schattner 2006).  Failure to achieve informed consent is the basis of many formal complaints, and costly litigation. Adequate information provision has additional wider benefits for patients, including increased satisfaction, more rapid symptom resolution, reduced emotional distress, reduced use of analgesia and possibly shorter hospital admissions (Egbert 1964; Hall 1988; Roter 2006).  Informed patients are more likely to make conservative treatment options, such as declining surgical procedures, thus possibly reducing overall health costs (Kennedy 2002). Synthesis of the evidence aimed to establish the most robust evidence for the effectiveness of interventions in this field and thus promote implementation and identify the need for further research. 

There may be some overlap with other reviews and protocols. Interventions to improve shared decision making (Duncan 2010; Légaré 2010) and informed consent in research have been reviewed (Ryan 2009), but there are no other Cochrane protocols or reviews that examine informed consent in relation to surgical or other invasive procedures alone. Gøtzsche and Jørgensen (Gøtzsche 2013) examined screening for breast cancer with mammography, noting the need for better information to promote informed consent for screening, but their review was not of interventions to promote informed consent. Other interventions, for example the provision of more information on a surgeon's performance, might also be of benefit; however Henderson and Henderson in their systematic review of this intervention identified no relevant studies (Henderson 2010).

Doust and colleagues (Doust 2007) are conducting a review of interventions to minimise harm from screening, including interventions which enhance knowledge about the benefits and harms of screening, but this does not consider any procedures that may follow the screening.  Our own earlier review on interventions before healthcare consultations for helping patients get the information they require (Kinnersley 2007) also does not focus on surgical procedures but covers a range of settings, including primary care and outpatient medical settings. The Cochrane review ‘Decision aids to help people who are facing health treatment or screening decisions’, by Stacey et al (Stacey 2011) includes trials in which decision aids have been used to help patients make a decision about treatment options, but the trials do not analyse the informed consent process itself, and many of them do not address conditions directly related to invasive procedures.

 

Objectives

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. Contributions of authors
  12. Declarations of interest
  13. Sources of support
  14. Differences between protocol and review
  15. Index terms

To assess the effects of interventions to promote informed consent for patients undergoing surgical or other invasive healthcare treatments and procedures.

 

Methods

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. Contributions of authors
  12. Declarations of interest
  13. Sources of support
  14. Differences between protocol and review
  15. Index terms
 

Criteria for considering studies for this review

 

Types of studies

Randomised controlled trials (RCTs) including cluster randomised trials.

 

Types of participants

Patients aged 16 years and over being asked to give consent for a surgical or other invasive healthcare treatment or procedure, either for themselves, or on behalf of a minor or someone else for whom they have responsibility. 

We excluded trials in which:·        

  • the patients were aged 16 years and over but were unable to consent to the procedure themselves (because they lacked capacity);·        
  • the patients were detained in hospital (for example under the Mental Health Act in the UK);
  • the consent being obtained was to take part in a research trial (even if the trial itself involved an invasive procedure). 

 

Types of interventions

Adhering to our protocol (Kinnersley 2011) we considered studies with interventions that:

  • targeted healthcare professionals, or patients, or both, who were participating in the consent process for a surgical or other invasive healthcare procedure, or
  • targeted organisational change of the consenting of these patients.

Interventions, even if targeted at clinicians, were required to have the intention of improving patients' understanding of their treatment options (including declining any intervention) and the procedure under consideration, evaluating their options, or helping them retain and recall the information provided, and thus their ability to provide informed consent. 

Where the interventions targeted patients, we included studies in which the participants were undergoing procedures, as well as studies in which patients were considering more generally the possible treatment options for their condition, as long as this included at least one surgical or invasive option.

We excluded interventions that focused on the condition alone, or on conditions for which there was no surgical or invasive option.  For example, interventions for patients undergoing cholecystectomy or considering treatment options for gallstones, which included cholecystectomy, were eligible to be included in the review.  However, interventions that simply provided more information about gallstones without consideration of treatment options were excluded, as were interventions providing information about treatment options for conditions such as eczema (for which there are, as far as we are aware, none requiring consent).

We included interventions in any format/medium.

Comparisons were made between interventions and usual care (controls).  Where there were multiple intervention arms we divided the control groups accordingly.

 

Types of outcome measures

We took a comprehensive approach to outcomes, as the obtaining of consent is a complex process with effects on the patient, the clinician and the healthcare system (CCCRG 2008).

 

Primary outcomes

 

Informed consent 

The primary outcome was ‘informed consent’.  For us to support an investigator’s view that he or she was measuring informed consent we sought evidence that the outcome measure took account of the patient going through the process of being provided with information about a procedure, which they had understood, retained and weighed up sufficiently to make a decision, which they had then communicated to the clinicians caring for them.

In doing this, we also considered Marteau’s model of informed choice (Marteau 2001) which places emphasis on patients’ decision making being supported by evidence of knowledge and consistent values (or satisfaction with the decision).

Ideally, informed consent or informed choice would be a single measure (dichotomised - achieved or not achieved) of the effects of the intervention for a patient. Although we took the view that it would be more likely that trials reported understanding/knowledge, retention/weighing up, attitudinal and uptake measures at group levels (e.g. Evans 2007) it proved difficult to interpret data on different outcomes within individual studies.  Instead we present the data for particular outcomes across studies and consider the meaning of these results in the Discussion.

 

Secondary outcomes

The initial secondary outcomes were the component elements of informed consent as described above.

 

Patient understanding

Since understanding has various facets and interpretations, we considered there was overlap between understanding, knowledge and recall.  However we used Mazur's model of understanding to develop a framework to assess the patient's level of understanding in more depth or to report single facets (e.g. knowledge) (Mazur 2009). Indeed in some studies authors stated that they were assessing understanding, but in fact used instruments measuring only recall or knowledge. In these cases, we re-classified the outcomes measured.  For example, if a researcher described the measurement of understanding when in fact we believed it to represent the measurement of knowledge, we classified this as knowledge; the distinction being that understanding implied a deeper level of comprehension. For instance, a patient may know that they need surgery because they have appendicitis, without necessarily understanding that they need surgery with an awareness to some extent of the pathophysiological process and the consequences of not having surgery.

We sought data on the following aspects of understanding:

  • Understanding in terms of asking the patient directly if the information had been understood (patient-reported understanding);
  • Understanding in terms of evidence of comprehension of the information provided, and the patient's situation beyond simple factual recall;
  • Understanding in terms of the way the patient used the information provided.  If the information has been understood, subsequent decisions by the patient should be consistent with their personal values.  Evidence of this process was considered to be present for the outcomes of deliberation and decisional conflict.

 

Knowledge/retention/recall

Knowledge/retention/recall were most commonly measured by assessing the extent to which the patient ‘knew’ the information with which they had been provided about the procedure; for example, what the patient knew about appendicectomy.  Most often it would be the case that patients were recalling information told to them during the consent consultation.  However, in some cases this knowledge may have reflected information that the patient had gathered before the consent process for this particular episode of health care.  So, before an episode of appendicitis, many patients will know that the appendix is a part of the bowel (although they may not understand what part of the bowel it is, and the role it plays in sickness and in health). For simplicity we equated ‘recall’ of information provided in the consent consultation with wider knowledge and have reported this as 'knowledge'.The timing of measurement of knowledge also provided information as to the retention of information.  To make comparisons we made a pragmatic decision to categorise the outcomes depending upon the time of measurement after the intervention into immediate (24 hours or less), short-term (between 24 hours and 14 days) and long-term (15 days or more).

 

Deliberation (weighing up)

Making an informed decision or choice requires someone to consider carefully (deliberate) or weigh up the information, and how it fits with their personal circumstances and values (Elwyn 2010). We examined studies in which researchers claimed to have measured deliberation, and report on both the methods used and the intervention effects.

 

Communication of decision

Communication of decision is generally demonstrated (in cases of assent to the procedure) by the patient signing a consent form as discussed above.  However, researchers may attempt to measure closely-related concepts, such as confidence in the decision, consistency of decision making or decisional conflict (Stacey 2011).

 

Other patient outcomes

We also collected data on:

  • Satisfaction and anxiety with decision making;
  • Satisfaction and anxiety with the consent process;
  • Desire for further information;
  • Sense of control - locus of control or perception of who made the decision:
  • Pain experienced or analgesia use.

 

Clinician outcomes

We collected data on the following clinician outcomes:

  • Satisfaction with the 'consent consultation' (or process);
  • Ease of use of intervention(s) to improve gaining of informed consent;
  • Confidence in patient's decision and whether an informed choice was made.

 

System outcomes

To further judge the effects of interventions, it was necessary to assess changes to the overall healthcare system, and further evidence of patient implementation of choices. We collected data on the following outcomes:

  • Rates of uptake (or refusal) of clinical interventions/procedures;
  • Postponement of clinical interventions/procedures;
  • Delay in decision making or request for more information/further consultations;
  • Complaints and litigation;
  • Adverse procedural outcomes;
  • Economic/resource use data (e.g. length of consultations, cost of surgery/procedure choices, number of consultations, and length of hospital stay).

 

Search methods for identification of studies

 

Electronic searches

We performed an electronic search from database inception to July 2011 in MEDLINE (OvidSP), EMBASE (OvidSP) and PsycINFO (OvidSP) using Medical Subject Headings and text words, applying a randomised controlled trial filter to capture the study types included in the review. We also searched the Cochrane Central Register of Controlled Trials (CENTRAL), The Cochrane Library, issue 5, 2012. We applied no language or date restrictions within the search. The detailed search strategies are in Appendices (1 to 4).

 

Searching other resources

We searched the reference lists of included trials and relevant published reviews to identify further potentially-relevant studies. We had planned to search a number of additional sources as specified in the review protocol (Kinnersley 2011), but decided that complete coverage of the area was already ensured by the our search of the above databases.

 

Data collection and analysis

 

Selection of studies

Stage 1

We conducted the searches for relevant trials, combining the results into a single database and eliminating duplicates.

Stage 2

We screened titles and abstracts to eliminate obviously irrelevant studies. To ensure consistent application of inclusion criteria, we screened the titles in batches of 20, with 3 authors discussing their results.  Disagreements were discussed with the wider author team.  Once a high level of consistency was achieved two authors worked independently on larger batches of abstracts, again with disagreements being discussed with the wider team.

Stage 3

We retrieved full text copies of all potentially-relevant papers, including those for which the description was insufficient to make a decision about inclusion.  Disagreement was resolved by discussion between the two assessing authors and an arbiter from the review team (PK or AE).  Studies excluded at this stage are listed in the Characteristics of excluded studies table.

Stage 4

Two review authors then reviewed relevant studies to ascertain whether there were multiple reports from single studies and linked these together if applicable to produce a final set of studies for inclusion in the review. These were entered into RevMan 5 software.

Stage 5

We scanned the reference lists of included studies to check for further possibly-relevant studies which had not been identified. These were re-entered at Stage 3.

 

Data extraction and management

Two authors independently extracted data from each included study using a modified Cochrane Consumers and Communication Group data collection checklist that had been predetermined and piloted by the review authors (Appendix 5). The authors each entered the data onto a separate electronic form. Discrepancies in data extraction were resolved by discussion between all review authors or, where this was not possible, between the two review authors extracting data and an arbiter (PK or AE). The data included the study methods, setting and participants, interventions, outcomes and results.

Extracted data were entered into RevMan 5 by one author and checked for accuracy against the original data by a different author (variable combinations of authors for individual studies). In cases of missing data we tried to contact the authors of the studies by email to obtain the relevant information.

 

Assessment of risk of bias in included studies

When assessing the risk of bias we used criteria in the 'Risk of bias' assessment tool (Higgins 2011). We assessed and reported on the risk of bias of included studies in accordance with the guidelines of the Cochrane Consumers and Communication Review Group (Ryan 2011), which recommends the explicit reporting of the following individual quality elements for RCTs: randomisation; allocation concealment; blinding (participants, personnel); blinding (outcome assessment); completeness of outcome data, selective outcome reporting; other sources of bias. In all cases, two authors independently assessed the risk of bias of included studies, with any disagreements resolved by discussion and consensus.  Table 1 shows an overview of the rules that we applied when assessing the risk of bias.

When assessing randomisation we checked that the investigators had described an adequate random component in the sequence generation. These were judged to have met this criterion were considered low risk of bias. Those that had used a non-random component were judged not to have met the criterion and marked as high risk.

We assessed whether allocation concealment was adequate and whether blinding was adequate, (blinding of the participants and personnel, performance bias and blinding of outcome assessment, detection bias) with those that were adequate being categorised as low risk and those that were judged to be inadequate being high risk. Where there was insufficient evidence, studies were classed as unclear.

We also examined outcome data to ensure that the effect of incomplete data (attrition bias) had been adequately addressed. Studies with no loss to follow up or an attrition rate of less than 40% were considered low risk and those that had a greater than 40% attrition were considered high risk. Where there was insufficient evidence, studies were classed as unclear.

We assessed selective outcome reporting as well. If a study had a protocol and this was followed then it was considered low risk, studies were considered high risk if one or more pre-specified outcomes were not reported. Studies with no available protocol were considered to be unclear.

We then looked at other potential risks of bias; such as threats to validity as detailed in the 'Risk of bias' assessment tool, potential contamination of the intervention or sources of funding leading to competing interests.

We contacted study authors for additional information about the included studies, or for clarification of the study methods as required. If we received no response, the study was marked as unclear for the relevant domain. We incorporated the results of the 'Risk of bias' assessment into the review through systematic narrative description and commentary about each of the items, leading to an overall assessment of the risk of bias of the included studies and a judgement about the internal validity of the review results.

 

Measures of treatment effect

The two main types of outcomes were continuous and dichotomous. Continuous outcomes were summarised using standardised estimated mean differences. Dichotomous outcomes were summarised using relative risks. For the measures of variance we calculated 95% confidence intervals for the effect estimates. If only non-parametric data were reported in studies, this was included as narrative description for each relevant outcome to summarise findings in the literature as fully as possible.

For the primary outcome (informed consent/choice), we aimed to identify reports of individual informed consent (achieved or not achieved) for meta-analysis. If there were studies which reported changes in understanding, values or choices made at group level only, we reported these separately and considered if it was appropriate to include them in a meta-analysis.

Where studies had multiple outcomes in the same outcome category we identified the main outcome for the study by:

  1. Selecting the primary outcome as identified by the publication authors;
  2. If no primary outcome was specified, selecting the one specified in the sample size calculation;
  3. If there was no sample size calculation, we ranked the effect estimates and selected the median effect estimate.

 

Unit of analysis issues

Studies in which clusters of individuals were randomised or allocated to intervention groups, but intervention was intended at the level of the individual, are problematic because they may lead to artificially small P values if standard statistical methods are used.  We intended to account for this by re-calculating the statistical significance accounting for intra-cluster correlations.  However, in the event only two studies were found that employed cluster randomisation (Paci 1999; Solberg 2010). Paci 1999 randomised by day of visit which would not be expected to produce appreciable clustering. Solberg 2010 randomised by centre but the impact of clustering possible from this one study was not deemed sufficient to re-analyse the data. We note the unit-of-analysis error.   

 

Dealing with missing data

We tried to contact all authors to obtain additional data. In addition we attempted to clarify the method of randomisation and whether allocation was concealed . We tried to carry out an intention-to-treat analysis where this was not reported by the authors and the authors did not respond to our enquiries. If sufficient data were not available, we carried out an available case analysis and consider the implications of the missing data in the Discussion section.

 

Assessment of heterogeneity

We assessed the statistical heterogeneity in meta-analyses by visually inspecting the scatter of effect estimates on forest plots and by the I2 statistic (Higgins 2003).  We categorised I2 values of 0% to 30% as indicating little evidence of heterogeneity, 31% to 60% as moderate heterogeneity, 61% to 80% as substantial heterogeneity and over 80% as considerable heterogeneity. 

 

Assessment of reporting biases

Where possible, we accessed the Clinical Trials Registry to determine whether studies were reporting their pre-specified primary outcomes. Where there was evidence of selective outcome reporting, this is reflected in the 'Risk of bias' assessment (see Assessment of risk of bias in included studies). Where sufficient RCTs and data for a given outcome were available, we conducted a visual inspection of the funnel plots to investigate any asymmetry as an indication of publication bias.

 

Data synthesis

For all studies, we have produced tables of summary statistics and graphs of the data.  Although the procedures vary in complexity, we consider it likely that it is the type of intervention which is more important than the type of procedure that was being undertaken, and therefore our main focus was on types of intervention and assessing whether there were consistent benefits (or harms) across similar interventions. 

We conducted a meta-analysis of those studies and outcomes which appear homogenous (minimum of three studies) (Treadwell 2006) using a random-effects model.  Although our original intention was only to conduct meta-analyses where heterogeneity was low (I2 statistic < 50%) we concluded it was more useful to conduct meta-analyses regardless of the  I2 statistic and leave it to the reader to take note of the heterogeneity of the studies. We performed data synthesis using RevMan 5.

 

Subgroup analysis and investigation of heterogeneity

Several features of the interaction between patient and clinician may affect communication, the interaction, and thus the opportunity to achieve informed consent for procedures. We planned and attempted to undertake the following comparisons:

  • face-to-face interventions versus distant interventions (for example web-based);
  • interventions targeted at clinicians versus those targeted at patients or at organisational change;
  • the age of patients (young 16 to 35 years; middle-aged 36 to 60 years; older 61 to 80 years, elderly over 80 years);
  • interventions targeted at a specific procedure (i.e. whether to undergo, for example, an operation such as knee replacement for osteoarthritis) or at a condition more generally (but for which at least one option may be surgical (e.g. a decision aid addressing menorrhagia)).

For the subgroup analyses we divided the studies into the subgroups of interest and conducted meta-analyses where possible.  We present for each subgroup analysis the standardised mean difference, confidence intervals and measure of heterogeneity for continuous data and, in the case of dichotomous data, relative risks, confidence intervals and measure of heterogeneity.

 

Sensitivity analysis

We conducted a sensitivity analysis based on the risk of bias identified in the studies. Studies identified as being of greatest risk of bias, specifically regarding randomisation, attrition and blinded outcome assessment were systematically removed from the analysis and we report the effects on the effect estimate.

 

Consumer participation

We engaged consumer input and representation from Cynnws Pobl (involving people), the consumer network of Clinical Research Collaboration Cymru, for advice on outcome measures, searching for types of interventions and assistance in analysis and interpretation of the effects of interventions across consumer/participant groups.

We also recruited clinician representatives to form a clinician reference group. A range of clinicians (surgical, medical and nursing) who are involved in the consent process were recruited from hospitals in South Wales and South West England, including surgical, radiological and other disciplines. They provided feedback on the results of the review and assisted with the writing of the plain language summary.

 

Results

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. Contributions of authors
  12. Declarations of interest
  13. Sources of support
  14. Differences between protocol and review
  15. Index terms
 

Description of studies

 

Results of the search

The electronic searches conducted yielded 12,283 references and other sources retrieved 1 reference. The number of records after removal of duplicates was 12,067. From these, we identified 271 papers for further examination of the full text. Ninety-five studies were identified for data extraction and preliminary inclusion but 30 of these studies were subsequently excluded (see Characteristics of excluded studies). Thus Sixty-five studies met our inclusion criteria and were included in the synthesis. A flow diagram of the study selection process is presented in Figure 1.

 FigureFigure 1. Study flow diagram.

 

Included studies

 

Size of review

We included 65 studies with a total of 9021 participants in the review (see Characteristics of included studies). Individual studies ranged from 20 participants (Wadey 1997) to 596 participants (Raynes-Greenow 2010).

Five studies (six intervention arms) contributed only non-parametric data so were included in qualitative synthesis only (Astley 2008a; Astley 2008b; Gerancher 2000; Lavelle-Jones 1993; Mason 2003; Wadey 1997).

In seven studies, two separate interventions were compared with one control (Agre 1994a; Agre 1994b; Astley 2008a; Astley 2008b; Bennett 2009a; Bennett 2009b; Cornoiu 2010a; Cornoiu 2010b;Kang 2009a; Kang 2009b; Mishra 2010a; Mishra 2010b; O'Neill 1996a; O'Neill 1996b). For these studies we split the control group to make independent comparisons with each intervention group. Each of these studies is listed twice in the Included studies list, to enable appropriate reporting and analysis. Overall, there are 72 treatment arms for analysis from the 65 studies.

 

Settings

Sixty three studies were set in hospital/secondary care and two studies were conducted in dental practice (Johnson 2006; Kang 2009a; Kang 2009b). Twenty five studies were from the USA, 14 from the UK, eight from Australia, seven from Canada, three from Germany, two from Ireland, and one from each of Austria, France, Italy, New Zealand, Switzerland and Turkey. Sixty three studies were written in English; one was translated from French (Danino 2006) and another from German (Hermann 2002).

 

Participants

Studies focused on adults who were providing informed consent for themselves (60 studies) or were doing this on behalf of a minor (5 studies). Studies had similar exclusion criteria, which referred to a lack of competence to consent or language barriers for the interventions.

 

Interventions

Intervention types were broadly grouped into audio-recorded aids (audio-cassette recording of the consultation or containing information about consent), non-interactive audio-visual aids (onscreen DVD, video or software package which the participant watched from beginning to end), interactive multimedia (onscreen DVD, video or software package for which the participant was able to select material to review out of order), written interventions (intervention delivered on paper), decision aids (including multi-component decision aids), structured consent processes (processes the clinician used to structure the consultation e.g. flip-sheets, question prompt sheets), question prompt sheets (given to the patient to use) or altering the timing of consent (relative to the time of the procedure). The interventions used in studies are summarised in the following table:

 

Procedures

Participants were generally those attending for elective procedures but included some emergency procedures. The procedures are summarised in the following table:


Procedure typeNumber of studies (intervention arms)References

Surgical32 (35 intervention arms)Armstrong 1997; Armstrong 2010; Ashraff 2006; Bollschweiler 2008; Chan 2002; Chantry 2010; Cornoiu 2010b; Cornoiu 2010a; Danino 2006; Deyo 2000; Fink 2010; Garrud 2001; Heller 2008; Henry 2008; Hong 2009; Langdon 2002; Lavelle-Jones 1993; Makdessian 2004; Mason 2003; Masood 2007; Mauffrey 2008; Mishra 2010b; Mishra 2010a; Nadeau 2010; Neary 2010; O'Neill 1996a; O'Neill 1996b; Pesudovs 2006; Rossi 2004; Rossi 2005; Rymeski 2010; Wadey 1997; Walker 2007; Wilhelm 2009; Zite 2011

Invasive medical procedure e.g. endoscopy, colonoscopy, angiogram, bronchoscopy10 (12 intervention arms)Agre 1994a; Agre 1994b; Astley 2008a; Astley 2008b; Elfant 1995; Enzenhofer 2004; Felley 2008; Friedlander 2011; Luck 1999; Phatouros 1995; Tait 2009; Uzbeck 2009

Anaesthetics e.g. general anaesthesia, epidural analgesia, regional anaesthesia4 (4 intervention arms)Garden 1996; Gerancher 2000; Kain 1997; Paci 1999

Electroconvulsive therapy1 (1 intervention arm)Greening 1999

Dental procedures2 (3 intervention arms)Johnson 2006; Kang 2009a; Kang 2009b

Paediatrics e.g. neonatal circumcision, inguinal hernia repair, ENT surgery, endoscopy or orthodontics5 (6 intervention arms)Chantry 2010; Friedlander 2011; Kang 2009a; Kang 2009b; Nadeau 2010; Rymeski 2010

Chemotherapy2 (2 intervention arms)Olver 2009; Thomas 2000

Antenatal screening procedures for Down Syndrome (including invasive options for screening)1 (1 intervention arm)Bekker 2004

Invasive radiology (spinal and facet joint injections, urography, intra-venous contrast CTs)5 (6 intervention arms)Bennett 2009a; Bennett 2009b; Cowan 2007; Hopper 1994; Neptune 1996; Yucel 2005



 

Description of interventions

 
Development

We analysed included studies for data on how the interventions were developed ( Table 2).  For 42 of 72 intervention arms (58.3%) it appeared that the interventions were designed for the trial with no validation or piloting (Armstrong 2010; Astley 2008a; Astley 2008b; Bekker 2004; Bennett 2009a; Bennett 2009b; Chan 2002; Chantry 2010; Cowan 2007; Danino 2006; Elfant 1995; Enzenhofer 2004; Fink 2010; Garden 1996; Garrud 2001; Greening 1999; Heller 2008; Henry 2008; Hermann 2002; Hong 2009; Kain 1997; Langdon 2002; Lavelle-Jones 1993; Makdessian 2004; Mason 2003; Mauffrey 2008; Mishra 2010a; Mishra 2010b; Neary 2010; O'Neill 1996a ;O'Neill 1996b; Olver 2009; Pesudovs 2006; Phatouros 1995; Raynes-Greenow 2010; Rossi 2004; Tait 2009; Wadey 1997; Walker 2007; Wilhelm 2009; Yucel 2005; Zite 2011).  For 16 of 72 intervention arms (22.2%) there appeared to be reasonable efforts to pilot and validate the interventions (Agre 1994a; Agre 1994b; Bollschweiler 2008; Cornoiu 2010a; Cornoiu 2010b; Deyo 2000; Goel 2001; Hopper 1994; Johnson 2006; Morgan 2000; Neptune 1996; Shorten 2005; Solberg 2010; Thomas 2000; Whelan 2003; Wong 2006).  For 4 of 72 intervention arms (5.5%) the intervention was modified from standard procedures (Kang 2009a; Kang 2009b; Masood 2007; Uzbeck 2009) and for another 4 intervention arms (5.5%) the intervention was the introduction of a standard procedure not currently in use (Friedlander 2011; Luck 1999; Rossi 2004; Rymeski 2010).  For 6 intervention arms (8.3%) no details were provided (Armstrong 1997; Ashraff 2006; Felley 2008; Gerancher 2000; Neary 2010; Paci 1999).

 
Exposure to the intervention

Studies were analysed for data on the number of exposures participants had to the interventions ( Table 2).  In 65 intervention arms (90.2%) participants were exposed to the intervention once (Agre 1994a; Agre 1994b; Armstrong 1997; Ashraff 2006; Astley 2008a; Astley 2008b; Bekker 2004; Bennett 2009a; Bennett 2009b; Bollschweiler 2008; Chan 2002; Chantry 2010; Cornoiu 2010a; Cornoiu 2010b; Cowan 2007; Danino 2006; Deyo 2000; Elfant 1995; Enzenhofer 2004; Felley 2008; Fink 2010; Friedlander 2011; Garden 1996; Garrud 2001; Gerancher 2000; Goel 2001; Greening 1999; Heller 2008; Henry 2008; Hermann 2002; Hong 2009; Hopper 1994; Johnson 2006; Kain 1997; Kang 2009a; Kang 2009b; Langdon 2002; Lavelle-Jones 1993; Luck 1999; Makdessian 2004; Mason 2003; Masood 2007; Mauffrey 2008; Morgan 2000; Nadeau 2010; Neary 2010; Neptune 1996; O'Neill 1996a; O'Neill 1996b; Olver 2009; Paci 1999; Pesudovs 2006; Phatouros 1995; Raynes-Greenow 2010; Rossi 2004; Rossi 2005; Rymeski 2010; Tait 2009; Uzbeck 2009; Wadey 1997; Walker 2007; Wilhelm 2009; Wong 2006; Yucel 2005; Zite 2011). One arm (1.4%) gave two exposures to the same intervention (Armstrong 2010). Four arms (5.5%) gave participants multiple exposures to the same Intervention (Mishra 2010a; Mishra 2010b; Thomas 2000; Whelan 2003). Two arms (2.7%) gave the consumers two exposures to two different interventions (Shorten 2005; Solberg 2010).

 
Training for delivery of intervention

For 35 intervention arms (48.6%) no details were provided of the training given to staff delivering the intervention ( Table 2) (Agre 1994b; Astley 2008a; Astley 2008b; Bollschweiler 2008; Chan 2002; Danino 2006; Elfant 1995; Fink 2010; Garden 1996; Garrud 2001; Gerancher 2000; Heller 2008; Henry 2008; Hong 2009; Hopper 1994; Kain 1997; Langdon 2002; Lavelle-Jones 1993; Makdessian 2004; Mason 2003; Mauffrey 2008; Morgan 2000; Nadeau 2010; Neptune 1996; O'Neill 1996a; O'Neill 1996b; Paci 1999; Pesudovs 2006; Phatouros 1995; Raynes-Greenow 2010; Rossi 2004; Shorten 2005; Solberg 2010; Walker 2007; Yucel 2005).  For 22 intervention arms (30.5%), little or no training appeared necessary, for example if the intervention was delivered by the participants viewing a video (Agre 1994a; Armstrong 1997; Ashraff 2006; Chantry 2010; Felley 2008; Friedlander 2011; Hermann 2002; Kang 2009a; Kang 2009b; Luck 1999; Masood 2007; Mishra 2010a; Mishra 2010b; Neary 2010; Olver 2009; Rossi 2005; Rymeski 2010; Tait 2009; Thomas 2000; Uzbeck 2009; Wilhelm 2009; Wong 2006).  For nine intervention arms (12.5%) brief training was given to staff involved (Armstrong 2010; Bennett 2009a; Bennett 2009b; Cornoiu 2010a; Cornoiu 2010b; Cowan 2007; Deyo 2000; Enzenhofer 2004; Goel 2001); for two intervention arms (2.7%) structured and extensive training was given (Johnson 2006; Whelan 2003); and for four intervention arms (5.5%) all interventions were delivered by the key researcher (Bekker 2004; Greening 1999; Wadey 1997; Zite 2011).

 
Evaluation of the delivery of the intervention

In 59 intervention arms (81.9%) there was no evidence of evaluation of the delivery of the intervention (Agre 1994a; Agre 1994b; Armstrong 1997; Armstrong 2010; Ashraff 2006; Bekker 2004; Bennett 2009a; Bennett 2009b; Chan 2002; Chantry 2010; Cornoiu 2010a; Cornoiu 2010b; Cowan 2007; Danino 2006; Elfant 1995; Fink 2010; Friedlander 2011; Garden 1996; Garrud 2001; Gerancher 2000; Goel 2001; Greening 1999; Heller 2008; Henry 2008; Hermann 2002; Hong 2009; Hopper 1994; Johnson 2006; Kain 1997; Kang 2009a; Kang 2009b; Langdon 2002; Lavelle-Jones 1993; Luck 1999; Makdessian 2004; Mason 2003; Masood 2007; Mauffrey 2008; Mishra 2010a; Mishra 2010b; Nadeau 2010; Neary 2010; O'Neill 1996a; O'Neill 1996b; Paci 1999; Pesudovs 2006; Phatouros 1995; Raynes-Greenow 2010; Rossi 2004; Rossi 2005; Solberg 2010; Tait 2009; Uzbeck 2009; Wadey 1997; Walker 2007; Whelan 2003; Wilhelm 2009; Yucel 2005; Zite 2011) and in 13 intervention arms (18.1%) there was evidence of checks on the fidelity and reliability of the delivery of the interventions ( Table 2) (Astley 2008a; Astley 2008b; Bollschweiler 2008; Deyo 2000; Enzenhofer 2004; Felley 2008; Morgan 2000; Neptune 1996; Olver 2009; Rymeski 2010; Shorten 2005; Thomas 2000; Wong 2006).

 
Details of the consent process in the control group

In 33 intervention arms (45.8%) the control groups received verbal information only in their consent consultation ( Table 2) (Armstrong 1997; Armstrong 2010; Ashraff 2006; Astley 2008a; Astley 2008b; Bekker 2004; Chantry 2010; Cowan 2007; Elfant 1995; Enzenhofer 2004; Felley 2008; Friedlander 2011; Hermann 2002; Hopper 1994; Johnson 2006; Langdon 2002; Lavelle-Jones 1993; Makdessian 2004; Mason 2003; Mauffrey 2008; Mishra 2010a; Mishra 2010b; Morgan 2000; Nadeau 2010; Neary 2010; Neptune 1996; Paci 1999; Rossi 2004; Rossi 2005; Rymeski 2010; Wadey 1997; Walker 2007; Wilhelm 2009).  In 23 intervention arms (30.9%) participants in the control group received standardised or particular written information as well as verbal information (Bollschweiler 2008; Danino 2006; Deyo 2000; Garden 1996; Garrud 2001; Goel 2001; Greening 1999; Heller 2008; Henry 2008; Kang 2009a; Kang 2009b; Luck 1999; O'Neill 1996a; O'Neill 1996b; Olver 2009; Phatouros 1995; Raynes-Greenow 2010; Solberg 2010; Thomas 2000; Uzbeck 2009; Whelan 2003; Yucel 2005; Zite 2011).  In 12 intervention arms (16.7%) the consenting clinician used a checklist of points to cover when talking to the patients (Agre 1994a; Agre 1994b; Bennett 2009a; Bennett 2009b; Chan 2002; Cornoiu 2010a; Cornoiu 2010b; Gerancher 2000; Hong 2009; Mauffrey 2008; Pesudovs 2006; Tait 2009).  In one intervention arm (1.4%) a dummy intervention was used (Wong 2006); in another one (1.4%) an audiovisual intervention was used (Fink 2010); and in two (2.8%) no details were provided (Kain 1997; Shorten 2005). See  Table 3 for an overview of the consent process in the control group.

 
Missing data/contact with authors

For 39 studies we sought clarification from the authors, usually about sources of bias, and we received responses from 28 authors (Armstrong 2010; Ashraff 2006; Bekker 2004; Bollschweiler 2008; Cornoiu 2010a; Cornoiu 2010b; Cowan 2007; Deyo 2000; Fink 2010; Garden 1996; Gerancher 2000; Greening 1999; Heller 2008; Henry 2008; Kain 1997; Kang 2009a; Kang 2009b; Luck 1999; Masood 2007; Mauffrey 2008; Mishra 2010a; Mishra 2010b; Morgan 2000; Nadeau 2010; Olver 2009; Pesudovs 2006; Phatouros 1995; Rossi 2004; Rossi 2005; Tait 2009; Wilhelm 2009) (contacted but no reply – Armstrong 1997; Bennett 2009a; Bennett 2009b; Chan 2002; Elfant 1995; Garrud 2001; Goel 2001; Johnson 2006; Lavelle-Jones 1993; Neptune 1996; Uzbeck 2009; Whelan 2003). We used unpublished data from 16 studies (Armstrong 2010; Bekker 2004; Cornoiu 2010a; Cornoiu 2010b; Cowan 2007; Fink 2010; Garden 1996; Kain 1997; Kang 2009a; Kang 2009b; Luck 1999; Mauffrey 2008; Mishra 2010a; Mishra 2010b; Morgan 2000; Nadeau 2010; Olver 2009; Tait 2009; Wilhelm 2009).

 

Excluded studies

We excluded 30 studies (see Characteristics of excluded studies). Seven of these studies (Altaie 2011; Clark 2011; Finch 2009; Gyomber 2010; Migden 2008; Scanlan 2003; Stanley 1998) met the inclusion criteria but had no usable data; details are shown in  Table 4.

 

Risk of bias in included studies

Overall 11 studies were considered to be at high risk of bias regarding random sequence generation, 9 at high risk for attrition bias and 20 studies were considered at high risk for blinding of outcomes (Figure 2). Please refer to Characteristics of included studies for further information on individual studies.

 FigureFigure 2. Risk of bias summary: review authors' judgements about each risk of bias item for each included study.

 

Allocation

Eleven studies (12 arms) were at high risk of selection bias with poor methods for random sequence generation (Armstrong 1997; Bennett 2009a; Bennett 2009b; Friedlander 2011; Garrud 2001; Mauffrey 2008; Olver 2009; Paci 1999; Pesudovs 2006; Rymeski 2010; Solberg 2010; Yucel 2005).

Eleven studies were at high risk of allocation/selection bias with no rigorous methodology to remove the chance of predicting allocation (Armstrong 2010; Chantry 2010; Friedlander 2011; Mauffrey 2008; Olver 2009; Paci 1999; Pesudovs 2006; Rossi 2005; Rymeski 2010; Tait 2009; Yucel 2005).

 

Blinding

Due to the nature of the research, informed consent was sought for these studies and some level of understanding of the group allocation by patients or clinicians was likely in most cases. Therefore blinding of participants or personnel was difficult to achieve. Fifty-one studies (58 arms) were at high risk of performance bias (Agre 1994a; Agre 1994b; Armstrong 1997; Armstrong 2010; Ashraff 2006; Astley 2008a; Astley 2008b; Bekker 2004; Bennett 2009a; Bennett 2009b; Bollschweiler 2008; Chan 2002; Chantry 2010; Cornoiu 2010a; Cornoiu 2010b; Cowan 2007; Elfant 1995; Enzenhofer 2004; Felley 2008; Fink 2010; Friedlander 2011; Gerancher 2000; Goel 2001; Greening 1999; Heller 2008; Hermann 2002; Hong 2009; Johnson 2006; Kain 1997; Kang 2009a; Kang 2009b; Langdon 2002; Luck 1999; Makdessian 2004; Mason 2003; Mauffrey 2008; Mishra 2010a; Mishra 2010b; Morgan 2000; Nadeau 2010; O'Neill 1996a; O'Neill 1996b; Olver 2009; Paci 1999; Pesudovs 2006; Rossi 2004; Rossi 2005; Rymeski 2010; Shorten 2005; Solberg 2010; Tait 2009; Thomas 2000; Uzbeck 2009; Wadey 1997; Walker 2007; Whelan 2003; Wilhelm 2009; Zite 2011).

Twelve studies (13 arms) were at high risk of detection bias (Chantry 2010; Fink 2010; Heller 2008; Hermann 2002; Hong 2009; Johnson 2006; Kang 2009a; Kang 2009b; Mauffrey 2008; Olver 2009; Rymeski 2010; Walker 2007; Zite 2011).

 

Incomplete outcome data

Three studies were at high risk of attrition bias due to attrition rates above the 40% threshold. In Chantry 2010 43% of the control group and 47% of the intervention group were lost to follow up; in Felley 2008 the drop out rate was 46%; and in Heller 2008 the drop out rate was 51%.

 

Selective reporting

Three studies were at high risk of reporting bias. In Chantry 2010 data on satisfaction were not included at one month follow up and only 10 of 14 questions were used in a composite knowledge score; in Friedlander 2011we judged there were differences between the registered protocol and the published report; and in Phatouros 1995 again there were missed data on outcomes which were reported in the methods as being measured.

 

Other potential sources of bias

Nine studies (10 arms) were at high risk of other bias with fidelity or contamination concerns (Bollschweiler 2008; Chantry 2010; Deyo 2000; Fink 2010; Henry 2008; Mauffrey 2008; O'Neill 1996a; O'Neill 1996b; Pesudovs 2006; Wilhelm 2009).

 

Effects of interventions

Studies using all types of intervention were included in the main analysis and contribute to the results. Subgroup analyses were then performed to evaluate the effects of face-to-face versus distant implementation of interventions, effects on different age groups, effects of different types of interventions, and effects of timing of the intervention prior to the procedure being undertaken.

Our main results are summarised in  Table 5.

 

Primary outcome: informed consent

One study with 47 participants in the intervention group and 50 participants in the control group measured informed consent (Friedlander 2011). This study examined the impact of a web-based learning module for parents of children undergoing endoscopy. The measure of consent was based on a modified questionnaire first published by Woodrow (Woodrow 2006), and included questions to examine the parent’s knowledge of risks, benefits and alternative treatments along with questions which explored if the parent understood what they had been told about risks, benefits, alternatives, their ability to explain what they had been told to another person and if they knew their right to refuse the procedure. A maximum score of 40 was considered to indicate that the participants had given informed consent. The intervention group (47 participants) had a statistically significantly higher mean score than the control group (50 participants) (Intervention group mean 37.4; control group mean 33.2; mean difference 4.16 (95% CI 2.52 to 5.80)) ( Analysis 1.1).

Meta-analysis for this primary outcome was not possible and the risk of bias was high for most domains, including two of the three deemed most important for this review (randomisation bias and attrition bias), but it was considered at low risk of bias for blinding of outcome assessment.

 

Secondary outcomes

 

Patient understanding

One study (two arms) measured patient understanding (Kang 2009a; Kang 2009b). The participants in this study were asked to apply the facts they had learnt to different scenarios, thus giving a measure of understanding rather than recall of simple facts. The participant responses to different scenarios were collected in a qualitative manner and then transcribed and assigned numerical values by the researchers. The trial had two intervention arms; the first intervention arm had a modified informed consent form (29 participants); the second intervention arm had the modified informed consent form and watched a slide-show (30 participants). The control group had usual care consisting of a standard consent form and standard written information (30 participants - divided into 15 for comparison with the two intervention arms). Those who had the modified informed consent form (the first intervention arm; Kang 2009a) showed no difference in their understanding from the control group (mean difference -0.7 (95% CI -10.32 to 8.92)). Those who had the modified written information and slide-show arm (second intervention arm, Kang 2009b) showed a statistically significantly improved understanding compared to the control group (mean difference 11.6 (95% CI 1.15 to 22.05)) ( Analysis 1.2).

 

Patient-reported understanding

Three studies had data that measured how much patients felt they had understood during the informed consent process; two of these studies (Hermann 2002; Walker 2007) reported continuous data and one study (Bollschweiler 2008) reported dichotomous data. The intervention group in Hermann 2002 showed greater self-reported understanding than those in the ‘usual care’ control group (mean difference 0.79 (95% CI 0.33 to 1.25)). Walker 2007 showed no statistically significant differences for self-reported understanding (mean difference 0.24 (95% CI -0.18 to 0.60)) ( Analysis 1.3). Bollschweiler 2008 showed the intervention group had a greater self-reported understanding than the control group (RR 1.84 (95% CI 1.35 to 2.51)) ( Analysis 1.4).

 

Knowledge (recall)

Knowledge was the most frequently-reported outcome in this review and was generally measured by whether participants could recall information that they had been given while being consented. We categorised this outcome into immediate (i.e. tested within 24 hours of intervention), short-term (more than 24 hours after intervention but less than 15 days later) and long-term knowledge (15 days or more after intervention). Many studies reported knowledge at two or more time periods so the studies have contributed data to different meta-analyses where appropriate. Continuous, dichotomous and non-parametric data were reported.

 
Immediate knowledge (tested less than 24 hours after the intervention)
 
Continuous data

Twenty two studies (26 intervention arms) with 1479 participants in the intervention and 1373 participants in the control groups reported this outcome (Agre 1994a; Agre 1994b; Armstrong 2010; Bekker 2004; Bennett 2009a; Bennett 2009b; Cornoiu 2010a; Cornoiu 2010b; Cowan 2007; Fink 2010; Garden 1996; Greening 1999; Hermann 2002; Hopper 1994; Johnson 2006; Kang 2009a; Kang 2009b; Morgan 2000; Nadeau 2010; Neptune 1996; Pesudovs 2006; Rossi 2004; Rossi 2005; Tait 2009; Walker 2007; Wong 2006). The meta-analysis showed a statistically significant increase in knowledge for the intervention compared to the control groups, with substantial heterogeneity (SMD 0.53 (95% CI 0.37 to 0.69) I2 73%) ( Analysis 1.5).

 
Sensitivity analysis

The sensitivity analyses did not substantially alter the magnitude or significance of the summary effect size.

1. Random sequence generation

Two studies (three intervention arms) were judged to have a high risk of bias (Bennett 2009a; Bennett 2009b; Pesudovs 2006). Removing these from the meta-analysis gave a new SMD of 0.52 with substantial heterogeneity ((95% CI 0.35 to 0.69) I2 75%).

2. Attrition bias

None of the studies were at high risk of attrition bias.

3. Blinding of outcome assessment

Five studies (six intervention arms) were judged to have a high risk of bias for blinded outcome assessment (Fink 2010; Hermann 2002; Johnson 2006; Kang 2009a; Kang 2009b; Walker 2007). Removing these from the meta-analysis gave an SMD of 0.61 with substantial heterogeneity ((95% CI 0.42 to 0.79) I2 71%).

Figure 3 shows a funnel plot of data for immediate knowledge.  There is some evidence of publication bias as the bottom left hand corner of the funnel plot shows fewer studies than might be expected.

 FigureFigure 3. Funnel plot of comparison: 2 All studies: interventions that promote informed consent, outcome: 2.7 Knowledge/retention/recall - Immediate.

 
Dichotomous data

Three studies (3 intervention arms) with 161 participants in the intervention groups and 170 participants in the control groups reported dichotomous data for immediate knowledge after an intervention (Mason 2003; Pesudovs 2006; Zite 2011). The combined risk ratio showed no difference in knowledge between the two groups, with considerable heterogeneity (RR 1.17 (95% CI 0.85 to 1.60) I2 84%) ( Analysis 1.8).

 
Non-parametric data

Three studies (4 intervention arms) with 208 participants in intervention groups and 175 in the control groups, report non-parametric data for immediate knowledge (Astley 2008a; Astley 2008b; Lavelle-Jones 1993; Mason 2003). Mason 2003 had a knowledge score out of 20: intervention arm median score 18 (Interquartile range (IQR) 16 to 18); control group median score 11.5 (IQR 10 to 15). Astley 2008a had two intervention arms (written information; animated audio-visual information; control verbal information).  A knowledge score out of 12 was recorded for each arm: written information arm median score 4 (IQR 3 to 5); audio-visual information median score 4 (IQR 3 to 6); control group median score of 3.5 (IQR 2 to 5). Lavelle-Jones 1993 had a recall score out of a total of 6; both the intervention and control groups scored 4 (both IQR were 2 to 6) ( Analysis 1.11).

 
Short-term knowledge (more than 24 hours, and up to and including 14 days after intervention)
 
Continuous data

Fourteen studies (16 intervention arms) with 1191 participants in the intervention and 915 participants in the control groups reported this outcome (Ashraff 2006; Chantry 2010; Cornoiu 2010a; Cornoiu 2010b; Enzenhofer 2004; Garrud 2001; Goel 2001; Heller 2008; Luck 1999; Nadeau 2010; O'Neill 1996a; O'Neill 1996b; Raynes-Greenow 2010; Tait 2009; Whelan 2003; Wilhelm 2009). The meta-analysis showed a statistically significant increase in knowledge for the intervention compared to the control groups, with considerable heterogeneity (SMD 0.68 (95% CI 0.42 to 0.93) I2 85%) ( Analysis 1.6).

 
Sensitivity analysis

The sensitivity analyses supported these findings when studies at high risk of attrition bias or poor blinding of outcome assessment were removed from meta-analysis.

1. Random sequence generation

One study was judged to have a high risk of bias for this domain (Garrud 2001). Removing its data from the meta-analysis gave an SMD of 0.62 with considerable heterogeneity ((95% CI 0.37 to 0.87) I2 84%).

2. Attrition bias

Three studies were judged to have a high risk of attrition bias (Chantry 2010; Heller 2008; Tait 2009). Removing these from the meta-analysis gave an SMD of 0.81 with considerable heterogeneity ((95% CI 0.50 to 1.13) I2 85%).

3. Blinding of outcome assessment

Two studies were judged to have a high risk of bias for this domain (Chantry 2010; Heller 2008). Removing these from the meta-analysis gave an SMD of 0.76 with considerable heterogeneity ((95% CI 0.47 to 1.05) I2 84%).

Figure 4 shows a funnel plot of data for short-term knowledge. There is spread of effect and study size suggesting low risk of publication bias.

 FigureFigure 4. Funnel plot of comparison: 2 All studies: interventions that promote informed consent, outcome: 2.8 Knowledge/Retention/Recall - Short term.

 
Dichotomous data

Two studies (2 intervention arms) with 167 participants in the intervention group and 162 participants in the control group measured short-term knowledge recall (Armstrong 1997; Elfant 1995). The results from Armstrong 1997 showed increased knowledge in the intervention group (RR 1.47 (95% CI 1.11 to 1.93)). Elfant’s results showed greater knowledge in the control group compared with the intervention group (RR 0.94 (95% CI 0.57 to 1.53)) ( Analysis 1.9).

 
Non-parametric data

One study (one intervention arm) with 121 participants in each group reported a knowledge test with a total score of 6 and showed the intervention increased knowledge (Lavelle-Jones 1993) (intervention arm median 4, IQR 2 to 6; control arm median 3, IQR 1 to 6 ( Analysis 1.11)).

 
Long-term knowledge (15 days and longer)
 
Continuous data

Fifteen studies (17 intervention arms) with 689 participants in the intervention and 664 in the control groups reported this outcome (Bekker 2004; Chan 2002; Cornoiu 2010a; Cornoiu 2010b; Danino 2006; Henry 2008; Hong 2009; Langdon 2002; Makdessian 2004; Mauffrey 2008; Mishra 2010a; Mishra 2010b; Pesudovs 2006; Rossi 2004; Rymeski 2010; Shorten 2005; Solberg 2010). The meta-analysis showed a statistically significant increase in knowledge for the interventions compared to the control groups with considerable heterogeneity (SMD 0.78 (95% CI 0.50 to 1.06) I2 82%)  Analysis 1.7.

 
Sensitivity analysis

The sensitivity analyses did not substantially alter the magnitude or significance of the summary effect size:

1. Random sequence generation

Four studies (four intervention arms) were judged to have a high risk of bias (Mauffrey 2008; Pesudovs 2006; Rymeski 2010; Solberg 2010). Removing these from the meta-analysis gave an SMD of 0.85 with considerable heterogeneity ((95% CI 0.50 to 1.21) I2 85%).

2. Attrition bias

None of the studies were at high risk of attrition bias.

3. Blinding of outcome assessment

Three studies (three intervention arms) were judged to have a high risk of bias for blinded outcome assessment (Hong 2009; Mauffrey 2008; Rymeski 2010). Removing these from the meta-analysis gave an SMD of 0.79 with considerable heterogeneity ((95% CI 0.46 to 1.12) I2 85%).

Figure 5 shows a funnel plot of data for long-term knowledge.  There is spread of effect and study size suggesting low risk of publication bias.

 FigureFigure 5. Funnel plot of comparison: 2 All studies: interventions that promote informed consent, outcome: 2.9 Knowledge/Retention/Recall - Long term.

 
Dichotomous data

Two studies (2 intervention arms) with 71 participants in the intervention groups and 80 participants in the control groups reported this outcome (Olver 2009; Pesudovs 2006).  In each study there was no statistical significance between the groups. Olver showed no statistical improvement in relative risk for the intervention group, RR 1.19 (95% CI 0.81 to 1.76). Pesudovs demonstrates no statistical improvement in relative risk for the control group, RR 0.94 (95% CI 0.75 to 1.18), again without statistical significance ( Analysis 1.10).

 
Non-parametric data

Five studies (six intervention arms) with 241 participants in the intervention and 207 participants in the control groups reported non-parametric data for long-term knowledge (Astley 2008a; Astley 2008b; Gerancher 2000; Greening 1999; Lavelle-Jones 1993; Wadey 1997). For Astley, the intervention group with written information had a median knowledge of 2 (out of total 12), IQR 1 to 3, the intervention group with audio-visual information had a median knowledge of 3, IQR 2 to 4, and the control group had median 3, IQR 1 to 4, suggesting that those with written information did more poorly on this test than the other two groups, which were similar. Gerancher reported improved knowledge in the intervention group (median 90 out of 100 versus 80 in the control group). Greening scored knowledge out of 12; the intervention arm showed improved knowledge with a median of 8 (IQR 1 to 12) and the control group had a median of 4 (IQR 0 to 12). Lavelle-Jones reported the same median of 3 in the intervention and the control groups (IQR for the intervention group was 2 to 6, and 1 to 6 for the control group). Wadey reported a knowledge score out of 6, the median for the intervention group was 3 (IQR 2 to 6) and a median for the control group of 3 (IQR 1 to 6) ( Analysis 1.11).

 

Deliberation

This outcome was not measured directly but one study (Bekker 2004) reported on informed decision making about the prenatal diagnosis of Down's syndrome. This study had 50 participants in the intervention and 56 in the control group. The authors measured informed decision making by coding themes discussed during consultations with the patient. The amount of information sought was given a numerical value for each theme discussed, with a total score of 7 possible (0 to 7; 7 = more informed decision making). The study found no statistically significant differences between the groups, MD 0.17 (95% CI -0.35 to 0.69) ( Analysis 1.12). However women who received the intervention were found to have evaluated more information during their consultations both positively and negatively, and were more likely to perceive the screening tests to be medium rather than high risk.

 

Communication of decision (decision conflict)

There were no studies that directly measured communication of decisions (i.e. choosing surgery or another option). However, it was proposed in the protocol (Kinnersley 2011) that studies may attempt to measure closely-related concepts such as decision conflict (if someone is in ‘conflict’ or uncertainty, they may be less likely to choose whether or not to undergo the procedure).

Three studies (3 intervention arms) with 526 participants in the intervention and 311 participants in the control groups reported decisional conflict using a common scale (the Decision Conflict Scale) (Goel 2001; Raynes-Greenow 2010; Shorten 2005). Two studies (Goel 2001; Raynes-Greenow 2010) reported scores after the intervention was used. Shorten reported a change in scores pre- and post-intervention. The meta-analysis showed a statistically significant decrease in the decisional conflict score in the intervention groups, with considerable heterogeneity (SMD -1.80 (95% CI -3.46 to -0.14) I2 99%) ( Analysis 1.13).

No exclusions for high risk of bias were required in the sensitivity analysis.

 

Other patient outcomes

 

Anxiety

Anxiety was divided into: general anxiety relating to the hospital stay or the procedure; anxiety concerning the consent process; and anxiety about the decision making process.

 
General anxiety
 
Continuous data

Twelve studies (14 intervention arms) with 1134 participants in the intervention and 935 participants in the control groups reported general anxiety (Bollschweiler 2008; Cornoiu 2010a; Cornoiu 2010b; Danino 2006; Felley 2008; Luck 1999; Mishra 2010a; Mishra 2010b; Neary 2010; Olver 2009; Raynes-Greenow 2010; Thomas 2000; Uzbeck 2009; Whelan 2003). The meta-analysis showed no statistically significant difference in the intervention groups compared to the control groups, with considerable heterogeneity (SMD -0.11 (95% CI -0.35 to 0.13) I2 82%) ( Analysis 1.14).

 
Sensitivity analysis

The sensitivity analyses did not substantially alter the magnitude or significance of the summary effect size:

1. Random sequence generation

One study was judged to have a high risk of bias for this domain (Olver 2009). Removing this from the meta-analysis gave an SMD of -0.12 with considerable heterogeneity ((95% CI -0.38 to 0.13) I2 83%).

2. Attrition bias

One study was judged to have a high risk of attrition bias (Felley 2008). Removing this study from the meta-analysis gave an SMD of -0.14 with considerable heterogeneity ((95% CI -0.42 to 0.15) I2 82%).

3. Blinding of outcome assessment

One study was judged to have a high risk of bias for blinded outcome assessment (Olver 2009). Removing this from the meta-analysis gave an SMD of -0.12 with considerable heterogeneity ((95% CI -0.38 to 0.13) I2 83%).

Figure 6 shows a funnel plot of data for generalised anxiety.  The pattern of effect and study size is symmetrical, suggesting low risk of publication bias.

 FigureFigure 6. Funnel plot of comparison: 2 All studies: interventions that promote informed consent, outcome: 2.16 General or procedural-related anxiety.

 
Dichotomous data

Two studies (2 intervention arms) with 145 participants in the intervention groups and 142 participants in the control groups reported the outcome of general anxiety (Johnson 2006; Thomas 2000). Johnson reported no statistically significant difference between groups (RR 0.67 (95% CI 0.32 to 1.41)). Thomas reported reduced anxiety in the intervention group compared to the control group (RR 0.47 (95% CI 0.31 to 0.72)) ( Analysis 1.15).

 
Anxiety with consent process
 
Continuous data

Eleven studies (13 intervention arms) with 727 participants in the intervention groups and 680 participants in the control groups reported data on anxiety with the consent process (Bekker 2004; Cornoiu 2010a; Cornoiu 2010b; Danino 2006; Fink 2010; Friedlander 2011; Garden 1996; Garrud 2001; Kain 1997; Kang 2009a; Kang 2009b; Walker 2007; Yucel 2005). The meta-analysis showed no overall differences between the groups with substantial heterogeneity (SMD 0.01 (95% CI -0.21 to 0.23) I2 70%) ( Analysis 1.16).

 
Sensitivity analysis

None of the sensitivity analyses substantially altered the magnitude or significance of the summary effect size:

1. Random sequence generation

Three studies (three intervention arms) were judged to have a high risk of bias for this domain (Friedlander 2011; Garrud 2001; Yucel 2005). Removing these from the meta-analysis gave an SMD of -0.12 with moderate heterogeneity ((95% CI -0.31 to 0.08) I2 41%).

2. Attrition bias

None of the reporting anxiety with the consent process studies at high risk of attrition bias.

3. Blinding of outcome assessment

Three studies (four intervention arms) were judged to have a high risk of bias for this domain (Fink 2010; Kang 2009a; Kang 2009b; Walker 2007). Removing these from the meta-analysis gave an SMD of -0.05 with moderate heterogeneity ((95% CI -0.23 to 0.33) I2 64%).

 
Dichotomous data

One study (one intervention arm) reported data on anxiety with the consent process with 29 participants in the intervention group and 36 in the control group (Phatouros 1995). This study found no statistically significant difference between the groups (RR 2.90 (95% CI 0.82 to 10.22)) ( Analysis 1.17).

 
Non-parametric data

Two studies (3 intervention arms) with 82 participants in the intervention groups and 48 in the control groups reported data on anxiety with the consent process (Astley 2008a; Astley 2008b; Mason 2003). In each study no statistically significant differences were found between the groups. Astley reports a median of 3 out of 5 on a Likert scale for both intervention and control groups (IQR 2 to 4). Mason reports on a State Trait Anxiety Inventory scale with median of 9 for the intervention group versus 10 for the control group (IQR 6 to 15 for both arms) ( Analysis 1.18).

 
Decision-related anxiety
 
Continuous data

One study reported data on anxiety with the decision process with 154 participants in the intervention group and 159 in the control group (Wong 2006). No differences were found between the two groups (MD 0.00 (95% CI -3.54 to 3.54)) ( Analysis 1.19).

 

Satisfaction

This outcome was divided into satisfaction with the consent process and satisfaction with decision making.

 
Satisfaction with the consent process
 
Continuous data

Thirteen studies (15 intervention arms) with 1046 participants in the intervention groups and 978 in the control groups reported satisfaction with the consent process (Armstrong 2010; Bekker 2004; Chantry 2010; Cornoiu 2010b; Cornoiu 2010a; Enzenhofer 2004; Felley 2008; Garrud 2001; Hopper 1994; O'Neill 1996b; O'Neill 1996a; Tait 2009; Uzbeck 2009; Walker 2007; Wilhelm 2009). The meta-analysis showed no statistically significant difference between groups with substantial heterogeneity (SMD 0.12 (95% CI -0.09 to 0.32) I2 76%) ( Analysis 1.20).

 
Sensitivity analysis

None of the sensitivity analyses substantially altered the summary effect size:

1. Random sequence generation

One study was judged to have a high risk of bias for this domain (Garrud 2001). Removing this study from the meta-analysis gave an SMD of 0.07 with substantial heterogeneity ((95% CI -0.13 to 0.27) I2 75%).

2. Attrition bias

Two studies were judged to have a high risk of attrition bias (Chantry 2010; Felley 2008). Removing these from the meta-analysis gave an SMD of 0.12 with substantial heterogeneity ((95% CI -0.14 to 0.39) I2 77%).

3. Blinding of outcome assessment

Three studies were judged to have a high risk of bias (Chantry 2010; Walker 2007; Wilhelm 2009). Removing these from the meta-analysis gave an SMD of 0.12 with substantial heterogeneity (95% CI -0.13 to 0.37) I2 79%).

Figure 7 shows a funnel plot of the data from the 'satisfaction with the consent process' outcome, There may be a small bias as a result of small studies with negative effects not being published.

 FigureFigure 7. Funnel plot of comparison: 2 All studies: interventions that promote informed consent, outcome: 2.22 Satisfaction with consent process.

 
Dichotomous data

Ten studies (10 intervention arms) with 515 participants in the intervention groups and 530 in the control groups reported data on satisfaction with the consent process (Bollschweiler 2008; Cowan 2007; Heller 2008; Johnson 2006; Olver 2009; Paci 1999; Pesudovs 2006; Phatouros 1995; Rossi 2005; Thomas 2000). The meta-analysis showed no difference in satisfaction with the consent process between the two groups, with substantial heterogeneity (RR 1.04 (95% CI 0.97 to 1.12) I2 75%) ( Analysis 1.21).

 
Sensitivity analysis:

None of the sensitivity analyses substantially altered the magnitude or significance of the summary effect size:

1. Random sequence generation

Three studies were judged to have a high risk of bias (Olver 2009; Paci 1999; Pesudovs 2006). Removing these from the meta-analysis gave an RR of 1.07 with considerable heterogeneity ((95% CI 0.95 to 1.19) I2 84%).

2. Attrition bias

One study were judged to have a high risk of attrition bias (Heller 2008). Removing this study from the meta-analysis gave an RR of 1.03 with substantial heterogeneity ((95% CI 0.96 to 1.11) I2 76%).

3. Blinding of outcome assessment

Three studies were judged to have a high risk of bias for this domain (Heller 2008; Johnson 2006; Olver 2009). Removing these from the meta-analysis gave an RR of 1.05 with considerable heterogeneity ((95% CI 0.95 to 1.16) I2 82%).

 
Non-parametric data

Two studies (3 intervention arms) with 98 participants in the intervention groups and 52 participants in the control groups report data on this outcome (Astley 2008a; Astley 2008b; Neary 2010). In both intervention groups for Astley, the intervention group had lower median satisfaction than in the control group (medians 4, 4, 5 respectively; IQR 4 to 5 for all 3 groups). Neary 2010 reported the same median satisfaction for the intervention arm and control arm (median 28 out of possible score of 30; IQR 26 to 30 for intervention; 25.3 to 30 for control) ( Analysis 1.22).

 
Satisfaction with decision making
 
Continuous data

Eight studies (8 intervention arms) with 1147 participants in the intervention groups and 997 participants in the control groups report continuous data for this outcome (Bekker 2004; Fink 2010; Goel 2001; Morgan 2000; Raynes-Greenow 2010; Solberg 2010; Whelan 2003; Wong 2006). The meta-analysis showed a statistically-significant increase in satisfaction in the intervention groups with considerable heterogeneity (SMD 2.25 (95% CI 1.36 to 3.15) I2 99%) ( Analysis 1.23).

 
Sensitivity analysis:

None of the sensitivity analyses substantially altered the magnitude or significance of the summary effect size:

1. Random sequence generation

One study was judged to have a high risk of bias for this domain (Solberg 2010). Removing this study from the meta-analysis gave an SMD of 2.57 with considerable heterogeneity ((95% CI 1.52 to 3.61) I2 99%).

2. Attrition bias

There were no studies at high risk for attrition bias.

3. Blinding of outcome assessment

One study was judged to have a high risk of bias (Fink 2010). Removing this from the meta-analysis gave an SMD of 3.07 with considerable heterogeneity ((95% CI 1.65 to 4.48) I2 99%).

 
Dichotomous data

One study (one intervention arm) with 171 participants in the intervention group and 172 participants in the control group reported data for this outcome (Deyo 2000). Deyo reported no statistically-significant difference between the groups (RR 0.94, 95% CI 0.79 to 1.11) ( Analysis 1.24).

 

Pain 

Five studies reported data on pain. Two studies (Felley 2008; Neary 2010) reported continuous data on pain levels; two studies (Deyo 2000; Phatouros 1995) reported dichotomous data on pain levels; and one study (Neary 2010) reported non-parametric data on analgesia use as per the WHO analgesic ladder.

 
Continuous data

Two studies (2 intervention arms) reported continuous data on pain with 309 participants in the intervention groups and 319 participants in the control groups (Felley 2008; Neary 2010). There were no statistically-significant differences between the groups in either study; Felley MD 0.11 (95% CI -0.06 to 0.27), Neary MD 0.03 (95% CI -0.54 to 0.59) ( Analysis 1.25).

 
Dichotomous data

Two studies (2 intervention arms) with 210 participants in the intervention groups and 213 participants in the control groups reported data for this outcome (Deyo 2000; Phatouros 1995). There were no statistically-significant differences between the groups in either study; Deyo RR 0.77 (95% CI 0.54 to 1.09) and Phatouros RR 1.41 (95% CI 0.64 to 3.13) ( Analysis 1.26).

 
Non-parametric data

One study reported data on analgesia use 24 hours after radio-guided parathyroidectomy, with 31 participants in the intervention group and 20 participants in the control group (Neary 2010). Results were similar between the two trial arms with a median in both groups of 1 (IQR 1 to 2;  Analysis 1.27).

 

Desire for further information

 
Dichotomous data

Four studies (4 intervention arms) with 503 participants in the intervention arms and 346 participants in the control arms report the outcome of desire for further information (Heller 2008; Paci 1999; Phatouros 1995; Raynes-Greenow 2010). The combined RR showed no statistical difference between participants' desire for further information, with moderate heterogeneity (RR 0.65 (95% CI 0.35 to 1.22) I2 57%) ( Analysis 1.28).

 

Sense of control – locus of control or perception of who made the decision

 
Continuous data

One study (one intervention arm) with 103 participants in the intervention group and 112 in the control group reported continuous data on the patients’ locus of control (Solberg 2010). Participants in the intervention group felt more strongly that it was their decision to make (regarding treatment options for uterine fibroids) than those in the control group, with statistical significance between groups (MD 0.30 (95% CI 0.07 to 0.53)) ( Analysis 1.29).

 
Dichotomous data

Three studies (3 intervention arms) with 561 participants in the intervention groups and 410 participants in the control groups reported data on the patients’ locus of control (Deyo 2000; Raynes-Greenow 2010; Whelan 2003). Meta-analysis showed no significant difference between the groups, with substantial heterogeneity (RR 1.03 (95% CI 0.98 to 1.09) I2 62%) ( Analysis 1.30).

 

Clinician outcomes

 

Satisfaction with the consent consultation

 
Continuous data

One study (one intervention arm) with 22 participants in the intervention group and 22 participants in the control group reported data from clinicians on their satisfaction with the consent consultation (Whelan 2003). Whelan et al report no statistically-significant differences between groups (MD 0.02 (95% CI -0.23 to 0.27)) ( Analysis 1.31).

 
Dichotomous data

One study (one intervention arm) with 13 participants in the intervention group and 13 participants in the control group reported data from clinicians on their satisfaction with the consent consultation (Solberg 2010). No statistically-significant differences were found between the groups (RR 0.82 (95% CI 0.53 to 1.26)) ( Analysis 1.32).

 

Ease of use of intervention(s) to improve gaining of informed consent

No studies reported this outcome.

 

Confidence in patients’ decision and whether an informed choice was made

No studies reported this outcome.

 

Systems/organisational outcomes

 

Rates of uptake (or refusal) of clinical interventions/procedures

For the purposes of analysis, uptake of the invasive procedure is presented as the outcome of interest.

 
Dichotomous data

Ten studies (10 intervention arms) with 1613 participants in the intervention groups and 1462 in the control groups reported data on this outcome (Bekker 2004; Cowan 2007; Deyo 2000; Felley 2008; Morgan 2000; Paci 1999; Raynes-Greenow 2010; Shorten 2005; Whelan 2003; Wong 2006). The meta-analysis showed no statistically-significant differences between the groups, with little heterogeneity (RR 0.98 (95% CI 0.95 to 1.02) I2 25%) ( Analysis 1.33).

 

Postponement of clinical interventions/procedures

No studies reported this outcome.

 

Delay in decision making or request for more information. Further consultations

No studies reported this outcome.

 

Complaints and litigation

No studies reported this outcome.

 

Adverse procedural outcomes

No studies reported this outcome.

 

Economic/resource use data

 

Length of consultation

 
Continuous data

Five studies (6 intervention arms) with 271 participants in the intervention groups and 246 participants in the control groups reported continuous data on the length of the consultation (Bekker 2004; Bennett 2009a; Bennett 2009b; Enzenhofer 2004; Hopper 1994; Whelan 2003). The meta-analysis showed that the control consultations were statistically-significantly shorter than the intervention consultations by a mean of 1.66 minutes, with little heterogeneity ((95% CI 0.82 to 2.50) I2 0%) ( Analysis 1.34).

 
Non-parametric data

One study (one intervention arm) with 251 participants in the intervention group and 258 participants in the control group reported non-parametric data on the consultation length (Fink 2010).  This showed a lower median consultation time in the control group than the intervention group (8.0 minutes versus 11.9 minutes, IQR of 4 to 11.9 and 7.2 to 15.0 respectively) ( Analysis 1.35).

 

Subgroup analyses

 

Face-to-face interventions versus distant interventions (e.g. web-based)

Interventions were categorised as either being delivered face-to-face with a clinician, or delivered without immediate contact with the clinician.

Face-to-face interventions: Sixteen studies (16 intervention arms) with 1549 participants in the intervention groups and 1321 participants in the control groups used interventions that the participant completed face-to-face with the clinician as part of the informed consent process (Agre 1994b; Bekker 2004; Bennett 2009a; Elfant 1995; Fink 2010; Goel 2001; Greening 1999; Johnson 2006; Morgan 2000; Neptune 1996; Raynes-Greenow 2010; Solberg 2010; Wadey 1997; Walker 2007; Whelan 2003; Wong 2006).

Interventions not requiring direct clinician contact to complete the intervention: 51 studies (56 intervention arms) with 3169 participants in the intervention groups and 2982 participants in the control groups were classified as not requiring clinician presence to complete the intervention part of the informed consent process (Agre 1994a; Armstrong 1997; Armstrong 2010; Ashraff 2006; Astley 2008a; Astley 2008b; Bennett 2009b; Bollschweiler 2008; Chan 2002; Chantry 2010; Cornoiu 2010b; Cornoiu 2010a; Cowan 2007; Danino 2006; Deyo 2000; Enzenhofer 2004; Felley 2008; Friedlander 2011; Garden 1996; Garrud 2001; Gerancher 2000; Heller 2008; Henry 2008; Hermann 2002; Hong 2009; Hopper 1994; Kain 1997; Kang 2009a; Kang 2009b; Langdon 2002; Lavelle-Jones 1993; Luck 1999; Makdessian 2004; Mason 2003; Masood 2007; Mauffrey 2008; Mishra 2010b; Mishra 2010a; Nadeau 2010; Neary 2010; O'Neill 1996b; O'Neill 1996a; Olver 2009; Paci 1999; Pesudovs 2006; Phatouros 1995; Rossi 2004; Rossi 2005; Rymeski 2010; Shorten 2005; Tait 2009; Thomas 2000; Uzbeck 2009; Wilhelm 2009; Yucel 2005; Zite 2011). 

We performed subgroup analyses for these studies for the outcomes of immediate and short-term knowledge, and anxiety with the consent process. Other meta-analyses were not possible, with less than three studies contributing data to other outcomes of direct comparable interest to those analysed in the main 'Effects of interventions' section. Meta-analysis of ‘satisfaction with the decision making’ was possible only for the face-to-face interventions, so does not differ from results already reported for this outcome.

 
Immediate knowledge

Face-to-face interventions: Ten studies (10 intervention arms) with 848 participants in the intervention groups and 829 participants in the control groups reported results for immediate knowledge (Agre 1994b; Bekker 2004; Bennett 2009a; Fink 2010; Greening 1999; Johnson 2006; Morgan 2000; Neptune 1996; Walker 2007; Wong 2006). Meta-analysis showed statistically-significantly improved knowledge in the face-to-face intervention groups compared with the control groups with substantial heterogeneity (SMD 0.52 (95% CI 0.28 to 0.76) I2 80%) ( Analysis 2.5).

Interventions not requiring direct clinician contact to complete the intervention: Fourteen studies (16 intervention arms) with 631 participants in the intervention groups and 544 participants in the control groups reported results for immediate knowledge (Agre 1994a; Armstrong 2010; Bennett 2009b; Cornoiu 2010b; Cornoiu 2010a; Cowan 2007; Garden 1996; Hermann 2002; Hopper 1994; Kang 2009a; Kang 2009b; Nadeau 2010; Pesudovs 2006; Rossi 2004; Rossi 2005; Tait 2009).  Meta-analysis showed statistically-significantly improved knowledge in the intervention groups compared with the control groups with substantial heterogeneity (SMD 0.53 (95% CI 0.32 to 0.75) I2 67%) ( Analysis 2.1).

 
Short-term knowledge

Face-to-face interventions: Three studies (3 intervention arms) with 508 participants in the intervention groups and 319 participants in the control groups reported results for short-term knowledge (Goel 2001; Raynes-Greenow 2010; Whelan 2003). Meta-analysis showed a statistically-significantly improvement in knowledge in the intervention groups compared to the control groups with moderate heterogeneity (SMD 0.35 (95% CI 0.12 to 0.59) I2 55%) ( Analysis 2.6).

Interventions not requiring direct clinician contact to complete the intervention: Eleven studies (13 intervention arms) with 683 participants in the intervention groups and 596 participants in the control groups reported results for short-term knowledge (Ashraff 2006; Chantry 2010; Cornoiu 2010b; Cornoiu 2010a; Enzenhofer 2004; Garrud 2001; Heller 2008; Luck 1999; Nadeau 2010; O'Neill 1996b; O'Neill 1996a; Tait 2009; Wilhelm 2009). Meta-analysis also showed a statistically-significant improvement in knowledge with considerable heterogeneity (SMD 0.79 (95% CI 0.44 to 1.14), I2 87%) ( Analysis 2.2).

 
Anxiety with the consent process

Face-to-face interventions: Three studies (3 intervention arms) with 374 participants in the intervention groups and 391 in the control groups reported results for anxiety with the consent process (Bekker 2004; Fink 2010; Walker 2007). There was no statistical difference in anxiety in the intervention groups compared with the control groups with substantial heterogeneity (SMD -0.08 (95% CI -0.41 to 0.25), I2 73%) ( Analysis 2.7).

Interventions not requiring direct clinician contact to complete the intervention: Eight studies (10 intervention arms) with 353 participants in the intervention groups and 289 in the control groups reported results for anxiety with the consent process (Cornoiu 2010b; Cornoiu 2010a; Danino 2006; Friedlander 2011; Garden 1996; Garrud 2001; Kain 1997; Kang 2009a; Kang 2009b; Yucel 2005). There was no statistical difference in anxiety in the intervention groups compared with the control groups with moderate heterogeneity (SMD 0.05 (95% CI -0.22 to 0.32) I2 58%) ( Analysis 2.3).

 
Length of consent consultation
 
Continuous data

Face-to-face interventions: Three studies (3 intervention arms) with 134 participants in the intervention groups and 127 participants in the control groups reported results for length of consultation (Bekker 2004, Bennett 2009a, Whelan 2003). The consultation was statistically-significantly longer in the intervention groups compared to the control groups with little heterogeneity (MD 2.81 minutes (95% CI 1.07 to 4.55) I2 5%) ( Analysis 2.8).

Interventions not requiring direct clinician contact to complete the intervention: Three studies (3 intervention arms) with 137 participants in the intervention arms and 119 participants in the control arms reported results (Bennett 2009b; Enzenhofer 2004; Hopper 1994). The consultation was statistically-significantly longer in the intervention groups compared to the control groups with little heterogeneity (MD 1.22 minutes (CI 95% 0.23 to 2.22) I2 0%) ( Analysis 2.4).

 

Interventions targeted at clinicians versus those targeted at patients or at organisational change

There were no studies with interventions that targeted clinicians, therefore this planned subgroup analysis was not possible.

 

Age of patients (young, middle-aged, older, elderly)

Subgroup analyses were only possible under this heading by considering studies in which parents or guardians provided consent on behalf of a minor, in contrast to other studies where mixed age-ranges of adult participants were used who were consenting for procedures for themselves (self-consent).

Five studies (6 intervention arms) with a total of 307 participants in the intervention groups and 247 participants in the control groups reported data for consent on behalf of a minor (Chantry 2010; Friedlander 2011; Kang 2009a; Kang 2009b; Nadeau 2010; Rymeski 2010). Meta-analysis was only possible on two outcomes: immediate knowledge and anxiety with the consent process.

 
Immediate knowledge

Consent on behalf of a minor: Two studies (3 arms) with 75 participants in the intervention groups and 48 in the control groups reported results in studies with parents or guardians providing consent (Kang 2009a; Kang 2009b; Nadeau 2010). There was a statistically-significant increase in knowledge in the intervention groups compared with the control groups with little heterogeneity (SMD 0.55 (95% CI 0.15 to 0.96) I2 13%) ( Analysis 3.1).

Self-consent: Twenty studies (23 intervention arms) with 1404 participants in the intervention groups and 1325 participants in the control groups report results for comparison on this outcome (Agre 1994a; Agre 1994b; Armstrong 2010; Bekker 2004; Bennett 2009a; Bennett 2009b; Cornoiu 2010b; Cornoiu 2010a; Cowan 2007; Fink 2010; Garden 1996; Greening 1999; Hermann 2002; Hopper 1994; Johnson 2006; Morgan 2000; Neptune 1996; Pesudovs 2006; Rossi 2004; Rossi 2005; Tait 2009; Walker 2007; Wong 2006). Meta-analysis shows a significant increase in immediate knowledge with substantial heterogeneity (SMD 0.52 (CI 95% 0.36 to 0.69) I2 75%) ( Analysis 3.3).

 
Anxiety with the consent process

Consent on behalf of a minor: Two studies (3 intervention arms) with 119 participants in the intervention groups and 93 in the control groups reported results in studies with parents or guardians providing consent (Friedlander 2011; Kang 2009a; Kang 2009b). There was no statistically-significant difference between the intervention groups compared with the control groups with moderate heterogeneity (SMD 0.14 (95% CI -0.30 to 0.57), I2 51%) ( Analysis 3.2).

Self-consent: Nine studies (10 intervention arms) with 608 participants in the intervention groups and 587 participants in the control groups reported results for comparison on this outcome (Bekker 2004; Cornoiu 2010a; Cornoiu 2010b; Danino 2006; Fink 2010; Garden 1996; Garrud 2001; Kain 1997; Walker 2007; Yucel 2005). Meta-analysis shows no difference statistically between groups with substantial heterogeneity (SMD -0.02 (CI 95% -0.28 to 0.23) I2 72%) ( Analysis 3.4).

 

Interventions targeted at a specific procedure (e.g. knee replacement) or condition more generally (e.g. decision-aid addressing menorrhagia including a surgical option)

There were insufficient data to report on this subgroup analysis for specific procedures. Specific types of interventions e.g. decision-aids, are addressed in the following post-hoc analyses.

 

Post-hoc analyses

We performed two post-hoc analyses. The first was based on classification of the main component of the interventions using the following categories: written, audio-visual; interactive multimedia; structured consent; and decision aids. The second additional subgroup analysis reports data split between interventions happening before admission to hospital and those happening at the time of admission.

 

Classification of the intervention

 
Written interventions

Written interventions were classified as interventions that use additional written materials. Twenty six studies (27 intervention arms) used written interventions (Armstrong 1997; Ashraff 2006; Astley 2008a; Bennett 2009b; Chan 2002; Cornoiu 2010b; Felley 2008; Garden 1996; Garrud 2001; Gerancher 2000; Henry 2008; Hong 2009; Kain 1997; Kang 2009a; Langdon 2002; Lavelle-Jones 1993; Makdessian 2004; Masood 2007; Mauffrey 2008; Nadeau 2010; O'Neill 1996b; O'Neill 1996a; Pesudovs 2006; Phatouros 1995; Uzbeck 2009; Yucel 2005; Zite 2011). Meta-analysis was possible for knowledge (immediate/short-term/long-term), generalised anxiety, anxiety with the consent process, and satisfaction with the consent process.

 
Immediate knowledge

Six studies (6 intervention arms) with 137 participants in the intervention and 99 in the control groups reported this outcome using written interventions (Bennett 2009b; Cornoiu 2010b; Garden 1996; Kang 2009a; Nadeau 2010; Pesudovs 2006).  The meta-analysis showed no difference between the groups with substantial heterogeneity (SMD 0.29 (95% CI -0.17 to 0.75) I2 65%) ( Analysis 4.1).

 
Short-term knowledge

Five studies (6 intervention arms) with 148 participants in the intervention and 117 in the control groups reported this outcome using written interventions (Ashraff 2006; Cornoiu 2010b; Garrud 2001; Nadeau 2010; O'Neill 1996b; O'Neill 1996a).    The meta-analysis showed statistically-significant improved knowledge in the intervention group with substantial heterogeneity (SMD 0.99 (95% CI 0.33 to 1.64) I2 80%) ( Analysis 4.2).

 
Long-term knowledge

Eight studies (8 intervention arms) with 296 participants in the intervention and 302 in the control groups reported this outcome using written interventions (Chan 2002; Cornoiu 2010b; Henry 2008; Hong 2009; Langdon 2002; Makdessian 2004; Mauffrey 2008; Pesudovs 2006).  The meta-analysis showed statistically significant improved knowledge in the intervention group with moderate heterogeneity (SMD 0.47 (95% CI 0.21 to 0.73) I2 58%) ( Analysis 4.3).

 
General anxiety

Three studies (3 intervention arms) with 361 participants in the intervention and 368 in the control groups reported this outcome using written interventions (Cornoiu 2010b; Felley 2008; Uzbeck 2009).  The meta-analysis showed no differences between the groups with considerable heterogeneity (SMD 0.36 (95% CI -0.17 to 0.89) I2 83%) ( Analysis 4.4).

 
Anxiety with the consent process

Six studies (6 intervention arms) with 211 participants in the intervention and 172 in the control groups reported this outcome using written interventions (Cornoiu 2010b; Garden 1996; Garrud 2001; Kain 1997; Kang 2009a; Yucel 2005).  The meta-analysis showed no differences between the groups with substantial heterogeneity (SMD 0.02 (95% CI -0.38 to 0.43) I2 67%) ( Analysis 4.5).

 
Satisfaction with the consent process

Five studies (6 intervention arms) with 416 participants in the intervention and 405 participants in the control groups reported this outcome using written interventions (Cornoiu 2010b; Felley 2008; Garrud 2001; O'Neill 1996b; O'Neill 1996a; Uzbeck 2009).  The meta-analysis showed no difference between the groups with considerable heterogeneity (SMD 0.19 (95% CI -0.29 to 0.67) I2 82%) ( Analysis 4.6).

 
Audio-visual Interventions

Audio-visual interventions were classified as interventions that used voice and pictures, for example a video. There were 19 studies (19 intervention arms) that used audio-visual interventions (Agre 1994a; Armstrong 2010; Astley 2008b; Bollschweiler 2008; Chantry 2010; Cornoiu 2010a; Cowan 2007; Danino 2006; Friedlander 2011; Hermann 2002; Kang 2009b; Luck 1999; Mason 2003; Olver 2009; Rossi 2004; Rossi 2005; Rymeski 2010; Thomas 2000; Wilhelm 2009). Meta-analysis was possible for knowledge (immediate/short-term), generalised anxiety, anxiety with the consent process and satisfaction with the consent process.

 
Immediate knowledge

Eight studies (8 intervention arms) with 345 participants in the intervention and 299 in the control groups reported this outcome using audio-visual interventions (Agre 1994a; Armstrong 2010; Cornoiu 2010a; Cowan 2007; Hermann 2002; Kang 2009b; Rossi 2004; Rossi 2005). The meta-analysis showed statistically-significantly improved knowledge in the intervention group with substantial heterogeneity (SMD 0.72 (95% CI 0.40 to 1.04) I2 71%) ( Analysis 4.7).

 
Short-term knowledge

Four studies (4 intervention arms) with 376 participants in the intervention and 321 in the control groups reported this outcome using audio-visual interventions (Chantry 2010; Cornoiu 2010a; Luck 1999; Wilhelm 2009).  The meta-analysis showed statistically-significantly improved knowledge in the intervention groups with considerable heterogeneity (SMD 0.73, 95% CI 0.14 to 1.32) I2 91%) ( Analysis 4.8).

 
General anxiety

Five studies (5 intervention arms) with 226 participants in the intervention and 218 in the control groups reported this outcome using audio-visual interventions (Bollschweiler 2008; Cornoiu 2010a; Luck 1999; Olver 2009; Thomas 2000).  The meta-analysis showed no difference between groups with considerable heterogeneity (SMD -0.48 (95% CI -1.07 to 0.12), I2 86%) ( Analysis 4.9).

 
Anxiety with the consent process

Four studies (4 intervention arms) with 142 participants in the intervention and 117 in the control groups reported this outcome using audio-visual interventions (Cornoiu 2010a; Danino 2006; Friedlander 2011; Kang 2009b).  The meta-analysis showed no statistically-significant difference between the groups with moderate heterogeneity (SMD 0.08 (95% CI -0.32 to 0.47) I2 53%) ( Analysis 4.10).

 
Satisfaction with the consent process

Continuous data: Four studies (4 intervention arms) with 343 participants in the intervention and 284 in the control groups reported this outcome using audio-visual interventions (Armstrong 2010; Chantry 2010; Cornoiu 2010a; Wilhelm 2009).  The meta-analysis showed no statistically significant difference between the groups with little heterogeneity (SMD 0.05 (95% CI -0.11 to 0.21) I2 0%) ( Analysis 4.11).

Dichotomous data: Four studies (4 intervention arms) with 252 participants in the intervention groups and 249 participants in the control groups reported dichotomous data for this outcome (Bollschweiler 2008; Olver 2009; Rossi 2005; Thomas 2000). The meta-analysis showed no difference between the groups with considerable heterogeneity (RR 1.10 (95% CI 0.91 to 1.34) I2 93%) ( Analysis 4.12).

 
Interactive multimedia

Interactive multimedia interventions were classified as any intervention that used pictures and voice but also required the user to actively participate in the process. There were six studies (six intervention arms) that used these interventions (Deyo 2000; Enzenhofer 2004; Heller 2008; Hopper 1994; Neary 2010; Tait 2009). Meta-analysis was possible for short-term knowledge and satisfaction with the consent process.

 
Short-term knowledge

Three studies (3 intervention arms) with 159 participants in the intervention and 158 participants in the control groups reported this outcome using interactive multimedia interventions (Enzenhofer 2004; Heller 2008; Tait 2009).  The meta-analysis showed statistically-significantly improved knowledge in the intervention group with moderate heterogeneity (SMD 0.47 (95% CI 0.16 to 0.77) I2 43%) ( Analysis 4.13).

 
Satisfaction with the consent process

Three studies (three intervention arms) with 174 participants in the intervention and 174 participants in the control groups reported this outcome using interactive multimedia interventions (Enzenhofer 2004; Hopper 1994; Tait 2009).  The meta-analysis showed no statistically-significant difference between the groups with considerable heterogeneity (SMD 0.23 (95% CI -0.46 to 0.92) I2 89%) ( Analysis 4.14).

 
Structured consent

Structured consent interventions were classified as interventions that involved providing additional structuring of the consent process, such as the clinician being trained to ask the patient to repeat back what they had been told. There were six studies (six intervention arms) that used these interventions (Agre 1994b; Bennett 2009a; Fink 2010; Greening 1999; Wadey 1997; Walker 2007).  Meta-analysis was possible for immediate knowledge.

 
Immediate knowledge

Five studies (5 intervention arms) with 442 participants in the intervention and 402 in the control groups reported this outcome using interventions focusing on structuring the consent consultation (Agre 1994b; Bennett 2009a; Fink 2010; Greening 1999; Walker 2007).  The meta-analysis showed statistically-significantly improved knowledge in the intervention group with moderate heterogeneity (SMD 0.43 (95% CI 0.16 to 0.70) I2 57%) ( Analysis 4.15).

 
Decision aids

Decision aid interventions were classified as interventions that used decision aids, either alone or in combination with other components.  There were nine studies (nine intervention arms) that used these interventions (Bekker 2004; Goel 2001; Johnson 2006; Morgan 2000; Raynes-Greenow 2010; Shorten 2005; Solberg 2010; Whelan 2003; Wong 2006).  Meta-analysis was possible for knowledge (immediate/short-term) and satisfaction with the consent process.

 
Immediate knowledge

Four studies (4 intervention arms) with 326 participants in the intervention and 347 in the control groups reported this intervention using interventions with decision aids (Bekker 2004; Johnson 2006; Morgan 2000; Wong 2006).  The meta-analysis showed statistically-significantly improved knowledge in the intervention group with considerable heterogeneity (SMD 0.64 (95% CI 0.26 to 1.02) I2 81%) ( Analysis 4.16).

 
Short-term knowledge

Three studies (3 intervention arms) with 508 participants in the intervention and 319 in the control groups reported this intervention using interventions with decision aids (Goel 2001; Raynes-Greenow 2010; Whelan 2003).  The meta-analysis showed statistically-significantly improved knowledge in the intervention group with moderate heterogeneity (SMD 0.35 (95% CI 0.12 to 0.59) I2 55%) ( Analysis 4.17).

 
Satisfaction with the decision-making process

Seven studies (7 intervention arms) with 884 participants in the intervention and 721 in the control groups reported this outcome using interventions with decision aids (Bekker 2004; Goel 2001; Morgan 2000; Raynes-Greenow 2010; Solberg 2010; Whelan 2003; Wong 2006). The meta-analysis showed statistically-significantly improved satisfaction in the intervention group with considerable heterogeneity (SMD 2.64 (95% CI 1.50 to 3.77), I2 99%) ( Analysis 4.18).

 

Timing of intervention

Interventions were divided into two groups, the first being interventions that happened before admission to hospital/place of procedure and the second being interventions that happened at the time of admission for a procedure. Classification was split according to when the intervention group had an intervention in studies where the control group had a component which was more than usual care. Two studies were excluded from this subgroup analysis because they used timing of consent as the intervention (Elfant 1995; Neptune 1996).

Subgroup meta-analysis was possible for the following outcomes: Immediate knowledge, short-term knowledge, long-term knowledge, generalised anxiety, anxiety with the consent process, and satisfaction with the consent process.

 
Intervention before admission for a procedure

Thirty nine studies (43 intervention arms) with 3211 participants in the intervention groups and 2898 participants in the control arms report data when the intervention happened before admission for a procedure (Ashraff 2006; Bekker 2004; Chan 2002; Chantry 2010; Cornoiu 2010a; Cornoiu 2010b; Danino 2006; Deyo 2000; Felley 2008; Fink 2010; Friedlander 2011; Garrud 2001; Goel 2001; Heller 2008; Henry 2008; Hong 2009; Kain 1997; Kang 2009a; Kang 2009b; Langdon 2002; Luck 1999; Makdessian 2004; Mason 2003; Mauffrey 2008; Mishra 2010a; Mishra 2010b; Morgan 2000; Nadeau 2010; Neary 2010; O'Neill 1996a; O'Neill 1996b; Olver 2009; Pesudovs 2006; Raynes-Greenow 2010; Rymeski 2010; Shorten 2005; Solberg 2010; Thomas 2000; Wadey 1997; Whelan 2003; Wilhelm 2009; Wong 2006; Zite 2011).

 
Immediate knowledge

Continuous data: Eight studies (10 intervention arms) with 699 participants in the intervention groups and 684 participants in the control groups reported results for interventions before admission for a procedure (Bekker 2004; Cornoiu 2010a; Cornoiu 2010b; Fink 2010; Kang 2009a; Kang 2009b; Morgan 2000; Nadeau 2010; Pesudovs 2006; Wong 2006). Meta-analysis showed a statistically-significant difference between the intervention and control groups with greater knowledge reported in the intervention group, however with considerable heterogeneity (SMD 0.50 (95% CI 0.16 to 0.85) I2 86%) ( Analysis 5.1).

 
Anxiety with the consent process

Continuous data: Eight studies (10 intervention arms) with 546 participants in the intervention groups and 518 participants in the control groups reported results for interventions before admission for a procedure (Bekker 2004; Cornoiu 2010a;Cornoiu 2010b; Danino 2006; Fink 2010; Friedlander 2011; Garrud 2001; Kain 1997; Kang 2009a; Kang 2009b). Meta-analysis showed no significant difference in anxiety between the two groups with substantial heterogeneity (SMD -0.12 (95% CI -0.33 to 0.09) I2 50%) ( Analysis 5.2).

 
Satisfaction with the consent process

Continuous data: Seven studies (9 intervention arms) with 708 participants in the intervention groups and 644 participants in the control groups reported results for interventions before admission for a procedure (Bekker 2004; Chantry 2010; Cornoiu 2010b; Cornoiu 2010a; Felley 2008; Garrud 2001; O'Neill 1996b; O'Neill 1996a; Wilhelm 2009). There was no significant difference in satisfaction between groups with substantial heterogeneity (SMD 0.14 (95% CI -0.12 to 0.41) I2 74%) ( Analysis 5.3).

Dichotomous data: Four studies (4 intervention arms) with 234 participants in the intervention groups and 226 participants in the control groups reported dichotomous results for interventions before admission for a procedure (Heller 2008; Olver 2009; Pesudovs 2006 ;Thomas 2000). There was no significant difference in satisfaction between groups with considerable heterogeneity (RR1.12 (95% CI 0.94 to 1.33) I2 91%) ( Analysis 5.4).

 
Intervention after admission for a procedure

Twenty four studies (27 intervention arms) with 1412 participants in the intervention groups and 1281 participants in the control groups report data where the interventions happened after admission for a procedure (Agre 1994a; Agre 1994b; Armstrong 1997; Armstrong 2010; Astley 2008a; Astley 2008b; Bennett 2009a; Bennett 2009b; Bollschweiler 2008; Cowan 2007; Enzenhofer 2004; Garden 1996; Gerancher 2000; Greening 1999; Hermann 2002; Hopper 1994; Johnson 2006; Lavelle-Jones 1993; Masood 2007; Paci 1999; Phatouros 1995; Rossi 2004; Rossi 2005; Tait 2009; Uzbeck 2009; Walker 2007; Yucel 2005).

 
Immediate knowledge

Continuous data: Thirteen studies (15 intervention arms) with 700 participants in the intervention groups and 609 in the control groups reported results for this outcome for interventions used after admission for a procedure (Agre 1994a; Agre 1994b; Armstrong 2010; Bennett 2009a; Bennett 2009b; Cowan 2007; Garden 1996; Greening 1999; Hermann 2002; Hopper 1994; Johnson 2006; Rossi 2004; Rossi 2005; Tait 2009; Walker 2007).  Meta-analysis showed a statistically-significant difference between the intervention and the control groups with greater knowledge reported in the intervention groups, with moderate heterogeneity (SDM 0.55 (95% CI 0.40 to 0.70) I2 40%) ( Analysis 5.5).

 
Anxiety with the consent process

Continuous data: Three studies (3 intervention arms) with 181 participants in the intervention groups and 162 in the control groups reported results for interventions used after admission for a procedure (Garden 1996; Walker 2007; Yucel 2005). In contrast to the before-admission interventions, meta-analysis showed statistically-significantly increased anxiety for the intervention groups with little or no heterogeneity (SDM 0.41 (95% CI 0.19 to 0.62) I2 0%) ( Analysis 5.6).

 
Satisfaction with the consent process

Continuous data: Six studies (6 intervention arms) with 338 participants in the intervention groups and 334 participants in the control groups reported results for interventions used after admission for a procedure (Armstrong 2010; Enzenhofer 2004; Hopper 1994; Tait 2009; Uzbeck 2009; Walker 2007). Meta-analysis showed no significant difference between the two groups with considerable heterogeneity (SDM 0.10 (95% CI -0.26 to 0.46) I2 81%) ( Analysis 5.7).

Dichotomous data: Six studies (6 intervention arms) with 281 participants in the intervention groups and 304 participants in the control arms reported dichotomous results for interventions used after admission for a procedure (Bollschweiler 2008; Cowan 2007; Johnson 2006; Paci 1999; Phatouros 1995; Rossi 2005). There was no significant difference in satisfaction with the consent process between the two groups with little heterogeneity (RR 1.00 (95% CI 0.96 to 1.04) I2 4%) ( Analysis 5.8).

 

Discussion

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. Contributions of authors
  12. Declarations of interest
  13. Sources of support
  14. Differences between protocol and review
  15. Index terms
 

Summary of main results

In this review we found that interventions to promote informed consent for patients undergoing surgical and other invasive healthcare procedures generally increased patients’ perceived knowledge and understanding. More specifically we found that immediate, short-term and long-term patient knowledge and satisfaction with decision making were increased, and decisional conflict was reduced. Satisfaction with the consent process, generalised anxiety and anxiety with the consent process were unchanged.  We also found that clinician and organisational outcomes were measured in a very limited number of studies. Where there were data, we found that for participants receiving the intervention, clinician satisfaction was unchanged, consultation length was slightly increased and uptake of procedures was unchanged.

This review also shows that further research is required; in particular, further consideration of how to measure informed consent as a unified concept.  In addition, more information is needed about the impact of interventions on clinicians of providing informed consent, the impact on healthcare organisations and particularly the uptake of procedures.  More recent studies appeared to be informed by the development of decision aids and an appreciation that consent should be a process rather than an event.  

 

Overall completeness and applicability of evidence

We identified a large number of relevant studies from a wide variety of settings.  Given the importance of informed consent to clinical care, it is encouraging to see the efforts being made to improve this process and the evidence that patients can benefit.  While it is disappointing to identify that a unified measure of informed consent was only attempted in one study, using interventions that improve components of informed consent should lead to improvements in consent itself.  It is also encouraging that potentially negative impacts of providing patients with more information, such as increased patient anxiety or increased consultation length, may be limited.

Increases in patient perceived understanding and knowledge seem beneficial since patient perception of care is important and this is consistent with the finding of an increase in satisfaction with decision making.  However more convincing is the evidence of increases in actual knowledge. Since the interventions were generally based around providing the patient with more information, it is probably not surprising that the interventions increased immediate knowledge. However, the evidence of growth in long-term knowledge (at longer than two weeks) suggests that the interventions had a real impact on patients’ understanding of the procedures they were undergoing.

Several of the meta-analyses are difficult to interpret because the levels of heterogeneity are high. The studies we were considering took place in a variety of settings and included patients undergoing a range of procedures.  In addition, varied measures were used for measuring outcomes.  In these circumstances high levels of heterogeneity might be anticipated. 

The timing of interventions to improve consent may be important.  In the past, consent was seen as an event, usually occurring shortly before the procedure itself, at the time when the patient arrived at the hospital.  This is clearly problematic since opportunities for the patient to deliberate on the information provided and consider their options or even simply ask questions is restricted by lack of time and the patient’s need to prepare him or herself for the procedure.  Making consent a process, whereby clinician and patient identify and plan the most appropriate treatment options, sharing information as they do so, and the patient is provided with time to consider the information before a final decision is made on which treatment is appropriate (including the option of doing nothing), may be more likely to result in informed consent.  Support for this approach may come from this review.  Our subgroup analyses looking at the timing of interventions identified that interventions both before and at the time of admission increased immediate knowledge, but suggest that those at the time of admission to hospital may increase anxiety with the consent process. It is a logical supposition that getting consent at the time of admission adds to the burden/work for the patient, but we have very low confidence in this result, given the analysis came from three small trials with variable risk of bias (Oxman 2004). This approach (ie seeking informed consent before the procedure) is also supported by the use of decision aids which, by their nature, have to be presented to the patient in advance of the procedure and provide more opportunity to deliberate.  Our subgroup finding that these interventions increased knowledge and reduced decisional conflict is encouraging and consistent with the review conducted by Stacey (Stacey 2011).

It is notable that limitation attention was paid in the studies we identified to both clinician and organisational outcomes.   For interventions to be taken up and used widely they need support from clinicians.  At the least they should not have negative impacts.  Some effects such as complaints and litigation which are of considerable significance around informed consent will occur too infrequently to be used as outcomes in relatively short-term trials, but when significant change occurs in a healthcare system it would be important to gather data on these outcomes. 

Rate of uptake of procedures is another complex outcome.  It was measured in 10 studies with over 3000 participants.  Interpretation is difficult because patients who were more fully informed might choose to have the procedure if this process indicated the procedure would produce benefits, alternatively they might be more likely to decline the procedure if little benefit was likely.  In addition, the timing of the intervention would again be important.  This is illustrated in the nature of the procedures being considered.  Some studies were designed to promote the non-uptake of invasive procedures (for example caesarean section (Shorten 2005)) while others were more neutral in their approach to treatments such as chemotherapy after breast cancer (Whelan 2003).

With regard to the particular format of the interventions used, for example written or audio-visual, it is difficult to draw conclusions.  Generally all formats improved knowledge but the findings across other outcomes are less consistent.  A number of factors will influence the impact of interventions employing different formats.  For example, if written materials are used in advance of admission to hospital they may act as ‘prompt sheets’ which are known to increase the question-asking by patients (Kinnersley 2007).

 

Quality of the evidence

The particular risks of bias that were judged as most likely to affect the results of studies in this review included random sequence generation flaws, attrition bias and poor blinding of outcome assessment.  Attrition bias was generally low since studies mainly collected outcome data at the time of consent or at the time of the procedure.

Blinding of outcomes was at high risk in about a quarter of included studies. This was most commonly because research assistants were not employed and clinical staff appeared to be conducting the studies and collecting data. However, in general when studies at high risk of bias were removed from the meta-analyses no major differences were apparent.

 

Potential biases in the review process

These results of this review need interpreting with caution.  Strengths of our review are that we undertook comprehensive search and review strategies and identified a large number of trials.  In addition we attempted to contact authors to clarify or obtain further data and we have considered and reported on a comprehensive group of outcomes.  However we only found one study reporting data on our primary outcome (Friedlander 2011) and, as has been discussed, the level of heterogeneity is high in many of the meta-analyses.  However, the heterogeneity of this review can also be seen as a strength. There appear to be enough data and significant findings on multiple outcomes to form broad conclusions for pragmatic application. The review does not answer questions for specific procedures, or identify how best to consent patients for one particular operation in one part of the world. We believe, however, there is useful evidence here regarding the impact of a number of essentially similar interventions on elements that can enhance informed consent.

 
Fidelity

Few studies in this review reported directly on adherence to the intervention. It is important to know to what extent participants actually used the intervention, and lack of adherence is more likely if the intervention is complex as was the case in many of the studies reported here.  If there is significant lack of adherence to the intervention, clearly the outcomes cannot then be attributed to the intended intervention. Notably, when internet-based interventions were used (e.g. Rymeski 2010) the inclusion of a tracking system to monitor participant progress through modules allowed for adherence to be reported relatively straight-forwardly.

 

Agreements and disagreements with other studies or reviews

To date, other systematic reviews have either looked specifically at interventions promoting informed consent for clinical research trials (e.g. Ryan 2009), or have included randomised and non-randomised studies (Schenker 2011). Schenker et al concluded that interventions improve comprehension, and that research is still needed to clarify and evaluate the effects of interventions on ‘informed consent’. Our review supports these findings but adds more robust data.  Like Schenker et al, we are unable to comment on whether interventions promote a wider concept of informed consent.

Ryan 2009 systematically reviewed the effects of audio-visual aids on informed consent for clinical trials. The findings in our review focusing on consent for procedures are more positive, demonstrating that audio-visual aids improve immediate and short-term knowledge and reduce generalised anxiety, without increasing anxiety with the consent process. Our review further looks at different types of interventions and compares the efficacy of these over within a range of outcomes. However, as has been found elsewhere, we are unable to clearly identify whether one particular type of intervention is better than another (Cohn 2007).

 

Authors' conclusions

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. Contributions of authors
  12. Declarations of interest
  13. Sources of support
  14. Differences between protocol and review
  15. Index terms

 

Implications for practice

For patients

This review identifies benefits for patients of using interventions to enhance the process of informed consent for invasive clinical procedures. Emergency procedures present particular challenges, but for routine, planned procedures it would appear that efforts should be made to provide patients with additional materials which provide information about the procedure, and patients should also be provided with time to consider the information.  We were unable to make comparisons between different groups of patients but the variety of patients included in our review would suggest that the results are reasonably generalisable.  In the case of vulnerable groups it would appear even more important that clinicians make efforts to ensure informed consent.

For clinicians

For clinicians, the studies reported have concluded no significant change in satisfaction with the consent consultation, as a result of interventions to promote informed consent. There were no data available on interventions targeted at clinicians and this may be an area of research in the future. Rates of uptake of procedures were also unchanged, although this may be confounded by preferred treatment choices influencing patient choice in some areas.

We present here evidence that indicates that for a wide range of procedures and settings, elements of the consent process can be improved. Since clinicians take responsibility for the consenting of patients they should also take responsibility for improving this process if possible. The previously routine process of simply providing patients with verbal information at the time of their admission to hospital may not benefit patients, and a more considered approach with enhanced information provision and time for consideration may be more beneficial.

Clinicians, those responsible for training clinicians, and researchers considering the design of interventions need to consider both ‘what’ information is provided to patients and ‘how’ this information is delivered.  Standardised consent forms in which clinicians are expected to confirm that they have provided particular information to patients may be helpful, but they may also promote a ‘tick-box’ approach to giving information, and risk the patient being overloaded with factual information which they may struggle to comprehend.  Silverman and colleagues (Silverman 2005) have summarized many of the deficiencies in information provision to patients and have identified key skills for enhanced information provision and discussion of plans.  These skills need to be combined with the skills for shared decision making (Elwyn 2012).  Informed consent is most likely to be achieved when the patient has had a discussion with a clinician who is both well informed and skilled at providing information, and who uses interventions as described in this review to at least enhance patient knowledge.  Patients then need an opportunity to deliberate on the choices available to them, and then be able to express their decision without feeling pressurized.

 
Implications for research

Achieving informed consent is a complex process.  Further research should appreciate this complexity and consider the overall pattern of outcomes achieved. It would also be helpful if there could be greater consensus on appropriate validated, reliable tools which measure outcomes such as knowledge and satisfaction, allowing improved comparison between studies.

If outcome measurements are more robust, research could benefit from looking in several directions. Further evaluation of different types of interventions is required so that conclusions can be drawn regarding which form of intervention (such as audio-visual, interactive multimedia, written information) is most beneficial in different settings, and whether there is any benefit in re-enforcing information with more than one intervention or if interventions are repeated. The timing of interventions during the process from diagnosis to procedure appears to be of importance and deserves further study.  There is little evidence at present to suggest the impact of interventions on clinicians. Further research in this area may be very informative and define the way that informed consent is addressed.

 

Acknowledgements

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. Contributions of authors
  12. Declarations of interest
  13. Sources of support
  14. Differences between protocol and review
  15. Index terms

We thank the translators of three papers, Katy Wilkinson (French paper, Danino 2006), Michaela Gal (excluded German paper, Lembcke 1998), and Jana Witt (German paper, Hermann 2002). James Ellis Jones, a patient with recent experience of health care in the UK; Mr Hunaid Vohra, cardiothoracic surgeon, Bristol; and Professor Steve Thomas, maxillo-facial surgeon, Bristol provided feedback and suggestions to improve the plain language summary. We also thank Sophie Hill, Megan Prictor and Jessica Thomas of the Cochrane Consumers and Communication Review Group for their help and support.

 

Data and analyses

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. Contributions of authors
  12. Declarations of interest
  13. Sources of support
  14. Differences between protocol and review
  15. Index terms
Download statistical data

 
Comparison 1. All studies: Interventions that promote informed consent

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Informed consent: continuous data1Mean Difference (IV, Random, 95% CI)Totals not selected

 2 Patient understanding: continuous data2Mean Difference (IV, Random, 95% CI)Totals not selected

 3 Patient self-report of understanding: continuous data2Std. Mean Difference (IV, Random, 95% CI)Totals not selected

 4 Patient self-report of understanding: dichotomous data1Risk Ratio (M-H, Random, 95% CI)Totals not selected

 5 Knowledge/retention/recall - immediate: continuous data262852Std. Mean Difference (IV, Random, 95% CI)0.53 [0.37, 0.69]

 6 Knowledge/retention/recall - short term: continuous data162106Std. Mean Difference (IV, Random, 95% CI)0.68 [0.42, 0.93]

 7 Knowledge/retention/recall - long term: continuous data171353Std. Mean Difference (IV, Random, 95% CI)0.78 [0.50, 1.06]

 8 Knowledge/retention/recall - immediate: dichotomous data3331Risk Ratio (M-H, Random, 95% CI)1.17 [0.85, 1.60]

 9 Knowledge/retention/recall - short term: dichotomous data2Risk Ratio (M-H, Random, 95% CI)Totals not selected

 10 Knowledge/retention/recall - long term: dichotomous data2Risk Ratio (M-H, Random, 95% CI)Totals not selected

 11 Knowledge/retention/recall: non-parametric dataOther dataNo numeric data

    11.1 Immediate knowledge
Other dataNo numeric data

    11.2 Short-term knowledge
Other dataNo numeric data

    11.3 Long-term knowledge
Other dataNo numeric data

 12 Deliberation: continuous data1Mean Difference (IV, Random, 95% CI)Totals not selected

 13 Decisional conflict: continuous data3837Std. Mean Difference (IV, Random, 95% CI)-1.80 [-3.46, -0.14]

 14 General or procedural-related anxiety: continuous data142069Std. Mean Difference (IV, Random, 95% CI)-0.11 [-0.35, 0.13]

 15 General or procedure-related anxiety: dichotomous data2Risk Ratio (M-H, Random, 95% CI)Totals not selected

 16 Anxiety (or other psychological stress) with consent process: continuous data131407Std. Mean Difference (IV, Random, 95% CI)0.01 [-0.21, 0.23]

 17 Anxiety (or other psychological stress) with consent process: dichotomous data1Risk Ratio (M-H, Random, 95% CI)Totals not selected

 18 Anxiety (or other psychological stress) with consent process: non-parametric dataOther dataNo numeric data

 19 Anxiety (or other psychological stress) with decision-making: continuous data1Mean Difference (IV, Random, 95% CI)Totals not selected

 20 Satisfaction with consent process: continuous data152024Std. Mean Difference (IV, Random, 95% CI)0.12 [-0.09, 0.32]

 21 Satisfaction with consent process: dichotomous data101045Risk Ratio (M-H, Random, 95% CI)1.04 [0.97, 1.12]

 22 Satisfaction with consent process: non-parametric dataOther dataNo numeric data

 23 Satisfaction with decision making: continuous data82144Std. Mean Difference (IV, Random, 95% CI)2.25 [1.36, 3.15]

 24 Satisfaction with decision making: dichotomous data1Risk Ratio (M-H, Random, 95% CI)Totals not selected

 25 Pain levels: continuous data2Std. Mean Difference (IV, Random, 95% CI)Totals not selected

 26 Pain levels: dichotomous data2Risk Ratio (M-H, Random, 95% CI)Totals not selected

 27 Analgesia use: non-parametric dataOther dataNo numeric data

 28 Desire for further information: dichotomous data4849Risk Ratio (M-H, Random, 95% CI)0.65 [0.35, 1.22]

 29 Sense of control - locus of control or perception of who made the decision: continuous data1Mean Difference (IV, Random, 95% CI)Totals not selected

 30 Sense of control - locus of control or perception of who made the decision: dichotomous data3971Risk Ratio (M-H, Fixed, 95% CI)1.03 [0.98, 1.09]

 31 Clinician outcome: satisfaction with the consent consultation: continuous data1Mean Difference (IV, Random, 95% CI)Totals not selected

 32 Clinician outcome: satisfaction with the consent consultation: dichotomous data1Risk Ratio (M-H, Random, 95% CI)Totals not selected

 33 Systems outcome: rates of uptake (or refusal) of clinical interventions/procedures: dichotomous data103075Risk Ratio (M-H, Random, 95% CI)0.98 [0.95, 1.02]

 34 Systems outcome: length of consultations: continuous data6517Mean Difference (IV, Random, 95% CI)1.66 [0.82, 2.50]

 35 Systems outcome: economic-time taken to consent: non-parametric dataOther dataNo numeric data

 
Comparison 2. Interventions that promote informed consent: Face-to-face interventions and distant interventions

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Distant interventions: knowledge/retention/recall - immediate161175Std. Mean Difference (IV, Random, 95% CI)0.53 [0.32, 0.75]

 2 Distant interventions: knowledge/retention/recall - short term131279Std. Mean Difference (IV, Random, 95% CI)0.79 [0.44, 1.14]

 3 Distant interventions: anxiety (or other psychological stress) with consent process10642Std. Mean Difference (IV, Random, 95% CI)0.05 [-0.22, 0.32]

 4 Distant interventions: systems outcome: length of consultations3256Mean Difference (IV, Random, 95% CI)1.22 [0.23, 2.22]

 5 Face to face interventions: knowledge/retention/recall - immediate101677Std. Mean Difference (IV, Random, 95% CI)0.52 [0.28, 0.76]

 6 Face to face interventions: knowledge/retention/recall - short term3827Std. Mean Difference (IV, Random, 95% CI)0.35 [0.12, 0.59]

 7 Face to face interventions: anxiety (or other psychological stress) with consent process3765Std. Mean Difference (IV, Random, 95% CI)-0.08 [-0.41, 0.25]

 8 Face to face interventions: systems outcome: length of consultations3261Mean Difference (IV, Random, 95% CI)2.81 [1.07, 4.55]

 
Comparison 3. Interventions to promote informed consent: consent on behalf of a minor and self consent

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Consent on behalf of a minor: knowledge/retention/recall - immediate3123Std. Mean Difference (IV, Random, 95% CI)0.55 [0.15, 0.96]

 2 Consent on behalf of a minor: anxiety (or other psychological stress) with consent process3212Std. Mean Difference (IV, Random, 95% CI)0.14 [-0.30, 0.57]

 3 Self-consent: knowledge/retention/recall - immediate232729Std. Mean Difference (IV, Random, 95% CI)0.52 [0.36, 0.69]

 4 Self-consent: anxiety (or other psychological stress) with consent process101195Std. Mean Difference (IV, Random, 95% CI)-0.02 [-0.28, 0.23]

 
Comparison 4. Interventions that promote informed consent : Classification of interventions

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Written: knowledge/retention/recall - immediate6236Std. Mean Difference (IV, Random, 95% CI)0.29 [-0.17, 0.75]

 2 Written: knowledge/retention/recall - short term6265Std. Mean Difference (IV, Random, 95% CI)0.99 [0.33, 1.64]

 3 Written: knowledge/retention/recall - long term8638Std. Mean Difference (IV, Random, 95% CI)0.47 [0.21, 0.73]

 4 Written: general or procedural-related anxiety3729Std. Mean Difference (IV, Random, 95% CI)0.36 [-0.17, 0.89]

 5 Written: anxiety (or other psychological stress) with consent process6383Std. Mean Difference (IV, Random, 95% CI)0.02 [-0.38, 0.43]

 6 Written: satisfaction with consent process6821Std. Mean Difference (IV, Random, 95% CI)0.19 [-0.29, 0.67]

 7 Audiovisual: knowledge/retention/recall - immediate8644Std. Mean Difference (IV, Random, 95% CI)0.72 [0.40, 1.04]

 8 Audiovisual: knowledge/retention/recall - short term4697Std. Mean Difference (IV, Random, 95% CI)0.73 [0.14, 1.32]

 9 Audiovisual: general or procedural-related anxiety5444Std. Mean Difference (IV, Random, 95% CI)-0.48 [-1.07, 0.12]

 10 Audiovisual: anxiety (or other psychological stress) with consent process4259Std. Mean Difference (IV, Random, 95% CI)0.08 [-0.32, 0.47]

 11 Audiovisual: satisfaction with consent process4627Std. Mean Difference (IV, Random, 95% CI)0.05 [-0.11, 0.21]

 12 Audiovisual: satisfaction with consent process (dichotomous)4502Risk Ratio (M-H, Random, 95% CI)1.10 [0.91, 1.34]

 13 Interactive multimedia: knowledge/retention/recall - short term3317Std. Mean Difference (IV, Random, 95% CI)0.47 [0.16, 0.77]

 14 Interactive multimedia: satisfaction with consent process3348Std. Mean Difference (IV, Random, 95% CI)0.23 [-0.46, 0.92]

 15 Structured: knowledge/retention/recall - immediate5844Std. Mean Difference (IV, Random, 95% CI)0.43 [0.16, 0.70]

 16 Decision aid: knowledge/retention/recall - immediate4673Std. Mean Difference (IV, Random, 95% CI)0.64 [0.26, 1.02]

 17 Decision aid: knowledge/retention/recall - short term3827Std. Mean Difference (IV, Random, 95% CI)0.35 [0.12, 0.59]

 18 Decision aids: satisfaction with decision making71605Std. Mean Difference (IV, Random, 95% CI)2.64 [1.50, 3.77]

 
Comparison 5. Interventions that promote informed consent: Timing of intervention

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Before admission: knowledge/retention/recall - immediate101383Std. Mean Difference (IV, Random, 95% CI)0.50 [0.16, 0.85]

 2 Before admission: anxiety (or other psychological stress) with consent process101064Std. Mean Difference (IV, Random, 95% CI)-0.12 [-0.33, 0.09]

 3 Before admission: satisfaction with consent process91352Std. Mean Difference (IV, Random, 95% CI)0.14 [-0.12, 0.41]

 4 Before admission: satisfaction with consent process (dichotomous)4460Risk Ratio (M-H, Random, 95% CI)1.12 [0.94, 1.33]

 5 After admission: knowledge/retention/recall - immediate151309Std. Mean Difference (IV, Random, 95% CI)0.55 [0.40, 0.70]

 6 After admission: anxiety (or other psychological stress) with consent process3343Std. Mean Difference (IV, Random, 95% CI)0.41 [0.19, 0.62]

 7 After admission: satisfaction with consent process6672Std. Mean Difference (IV, Random, 95% CI)0.10 [-0.26, 0.46]

 8 After admission: satisfaction with consent process (dichotomous)6585Risk Ratio (M-H, Random, 95% CI)1.00 [0.96, 1.04]

 

Appendices

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. Contributions of authors
  12. Declarations of interest
  13. Sources of support
  14. Differences between protocol and review
  15. Index terms
 

Appendix 1. MEDLINE (OvidSP) (1947 to July 2011)

1. exp informed consent/

2. (informed adj2 (consent or decision* or choice*)).tw.

3. informed decision making.tw.

4. consent comprehension.tw.

5. informed choice.tw.

6. informed consent recall.tw.

7. (consent* adj (process or form* or document*)).tw.

8. improving informed consent.tw.

9. (improv* adj2 consent).tw.

10. (understanding adj2 consent).tw.

11. consent process.tw.

12. *"Parental Consent"/

13. Parental Education as topic/

14. or/1-13

15. exp health education/

16. health knowledge attitudes practice/

17. ((health or patient or client) adj (education or knowledge or information or communication)).tw.

18. education/

19. ((education* or teaching or learning or training or skills or online or on-line or web* or internet or video* or multimedia or multi-media) adj (intervention* or session* or course* or program* or material* or package*)).tw.

20. ((improv* or increas* or enhanc*) adj3 (understanding or comprehension)).tw.

21. ((educat* or instruct* or advis* or advice* or counsel* or teach* or train* or coach* or learn*) and (Patient* or client* or consumer* or user* or carer* or caregiver* or care giver*)).tw.

22. exp professional patient relations/

23. hospital patient relations/

24. "referral and consultation"/

25. interviews as topic/

26. (consult* or interview).tw.

27. information services/

28. information dissemination/

29. access to information/

30. (information* adj (service* or system* or dissemination or seeking or provision or aid* or material* or sheet* or package*)).tw.

31. ((patient or client or written or print* or visual* or providing) adj information).tw.

32. (inform* adj2 (patient* or client*)).tw.

33. communication/

34. exp communications media/

35. ((mass or communication* or electronic or multi or print* or social or new) adj media).tw.

36. video recording/

37. (radio or televisions or audio* or video* or tape or recording* or cassette* or cd-rom* or dvd* or film* or mulimedia or hypermedia or telephon* or phone or sms or short message* or text message* or internet or web* or email* or electronic mail* or online or on-line or blog* or telemedicine or telehealth or virtual reality).tw.

38. ((print* adj (media or material* or based)) or paper based or publication* or brochure* or pamphlet* or leaflet* or flyer* or handout* or poster* or illustrat* or picture* or image* or pictorial* or pictogram*).tw.

39. exp computer systems/

40. online systems/

41. medical informatics/

42. exp informatics/

43. information systems/

44. software/

45. computer assisted instruction/

46. (computer* adj1 (system* or network* or program* or terminal* or interface* or interact* or intervention* or graphic* or game* or simulation* or searching or mediated or based or tailored or communication or assisted)).tw.

47. (interactive adj3 (program* or software or online or on-line or media or technolog* or communication or health*)).tw.

48. user computer interface/

49. computer graphics/

50. video games/

51. decision making/

52. decision support techniques/

53. (decision adj (aid* or support or tool*)).tw.

54. exp counseling/

55. translating/

56. multilingualism/

57. cultural* competen*.mp.

58. ((cultural* adj3 communication) or interpreter* or interpreting or translator* or translating).tw.

59. exp education, medical/

60. (((continuing or residency or distance) adj2 education) or internship or interns or inservice or in-service or staff-development).mp.

61. or/15-60

62. 14 and 61

63. randomized controlled trial.pt.

64. controlled clinical trial.pt.

65. randomized.ab.

66. placebo.ab.

67. randomly.ab.

68. trial.ab.

69. groups.ab.

70. or/63-69

71. exp animals/not humans.sh.

72. 70 not 71

73. 62 and 72

 

Appendix 2. EMBASE (OvidSP) (1980 to July 2011)

1. exp informed consent/

2. (informed adj2 (consent or decision* or choice*)).tw.

3. informed decision making.tw.

4. consent comprehension.tw.

5. informed choice.tw.

6. informed consent recall.tw.

7. (consent* adj (process or form* or document*)).tw.

8. improving informed consent.tw.

9. (improv* adj2 consent).tw.

10. (understanding adj2 consent).tw.

11. consent process.tw.

12. "Parental Consent"/

13. Parental Education as topic/

14. or/1-13

15. exp health education/

16. health knowledge attitudes practice/

17. ((health or patient or client) adj (education or knowledge or information or communication)).tw.

18. education/

19. ((education* or teaching or learning or training or skills or online or on-line or web* or internet or video* or multimedia or multi-media) adj (intervention* or session* or course* or program* or material* or package*)).tw.

20. ((improv* or increas* or enhanc*) adj3 (understanding or comprehension)).tw.

21. ((educat* or instruct* or advis* or advice* or counsel* or teach* or train* or coach* or learn*) and (patient* or client* or consumer* or user* or carer* or caregiver* or care giver*)).tw.

22. exp professional patient relations/

23. hospital patient relations/

24. "referral and consultation"/

25. interviews as topic/

26. (consult* or interview).tw.

27. information services/

28. information dissemination/

29. access to information/

30. (information* adj (service* or system* or dissemination or seeking or provision or aid* or material* or sheet* or package*)).tw.

31. ((patient or client or written or print* or visual* or providing) adj information).tw.

32. (inform* adj2 (patient* or client*)).tw.

33. communication/

34. exp communications media/

35. ((mass or communication* or electronic or multi or print* or social or new) adj media).tw.

36. video recording/

37. (radio or television or audio* or video* or tape or recording* or casette* or cd-rom* or dvd* or film* or multimedia or hypermedia or telephon* or phone or sms or short message* or text message* or internet or web* or email* or elctronic mail* or online or on-line or blog* or telemedicine or telehealth or virtual reality).tw.

38. ((print* adj (media or material* or based)) or paper based or publication* or brochure* or pamphlet* or leaflet* or flyer* or handout* or poster* or illustrat* or picture* or image* or pictorial* or pictogram*).tw.

39. exp computer systems/

40. online systems/

41. medical informatics/

42. exp informatics/

43. information systems/

44. software/

45. computer assisted instruction/

46. (computer* adj1 (system* or network* or program* or terminal* or interface* or interact* or intervention* or graphic* or game* or simulation* or searching or mediated or based or tailored or communication or assisted)).tw.

47. (interactive adj3 (program* or software or online or on-line or media or technolog* or communication or health*)).tw.

48. user computer interface/

49. computer graphics/

50. video games/

51. decision making/

52. decision support techniques/

53. (decision adj (aid* or support or tool*)).tw.

54. exp counseling/

55. translating/

56. multilingualism/

57. cultural* competen*.mp.

58. ((cultural* adj3 communication) or interpreter* or interpreting or translator* or translating).tw.

59. exp education, medical/

60. (((continuing or residency or distance) adj2 education) or internship or interns or inservice or in-service or staff-development).mp.

61. or/15-60

62. 14 and 61

63. randomized controlled trial/

64. random$.tw.

65. exp controlled study/

66. double blind procedure/

67. single blind procedure/

68. crossover procedure/

69. latin square design/

70. multicenter study/

71. ((clinical or controlled or comparative or placebo or prospective or random$) adj3 (trial or study)).tw.

72. ((single$ or doubl$ or trebl$ or tripl$) adj7 (blind$ or mask$)).tw.

73. (crossover$ or cross-over$ or (cross adj1 over$)).tw.

74. ((allocat$ or allot$ or assign$ or divid$) adj3 (condition$ or experiment$ or intervention$ or treatment$ or therap$ or control$ or group$)).tw.

75. or/63-74

76. 62 and 75

 

Appendix 3. PsycINFO (OvidSP) (1801 to July 2011)

1. exp informed consent/

2. (informed adj2 (consent or decision* or choice*)).tw.

3. informed decision making.tw.

4. consent comprehension.tw.

5. informed choice.tw.

6. informed consent recall.tw.

7. (consent* adj (process or form* or document*)).tw.

8. improving informed consent.tw.

9. (improv* adj2 consent).tw.

10. (understanding adj2 consent).tw.

11. consent process.tw.

12. parent* consent.tw.

13. exp PARENT TRAINING/

14. or/1-13

15. exp health education/

16. exp Health Behavior/or exp Knowledge Level/or exp Client Education/or exp Health Education/or exp Health Knowledge/or exp Health Attitudes/

17. ((health or patient or client) adj (education or knowledge or information or communication)).tw.

18. exp Health Education/or exp Education/

19. ((education* or teaching or learning or training or skills or online or on-line or web* or internet or video* or multimedia or multi-media) adj (intervention* or session* or course* or program* or material* or package*)).tw.

20. ((improv* or increas* or enhanc*) adj3 (understanding or comprehension)).tw.

21. ((educat* or instruct* or advis* or advice* or counsel* or teach* or train* or coach* or learn*) and (patient* or client* or consumer* or user* or carer* or caregiver* or care giver*)).tw.

22. exp Information Systems/or exp Health Care Delivery/or exp Technology/

23. exp THERAPEUTIC PROCESSES/

24. exp Professional Referral/

25. exp Interviews/

26. (consult* or interview).tw.

27. information services/

28. information dissemination/

29. exp Information Seeking/

30. (information* adj (service* or system* or dissemination or seeking or provision or aid* or material* or sheet* or package*)).tw.

31. ((patient or client or written or print* or visual* or providing) adj information).tw.

32. (inform* adj2 (patient* or client*)).tw.

33. exp Communication Barriers/or exp Computer Mediated Communication/or exp Communication/or exp Oral Communication/or exp Verbal Communication/or exp Written Communication/or exp Nonverbal Communication/or exp Interpersonal Communication/

34. exp communications media/

35. ((mass or communication* or electronic or multi or print* or social or new) adj media).tw.

36. exp Videotapes/or exp Videotape Recorders/

37. (radio or television or audio* or video* or tape or recording* or casette* or cd-rom* or dvd* or film* or multimedia or hypermedia or telephon* or phone or sms or short message* or text message* or internet or web* or email* or elctronic mail* or online or on-line or blog* or telemedicine or telehealth or virtual reality).tw.

38. ((print* adj (media or material* or based)) or paper based or publication* or brochure* or pamphlet* or leaflet* or flyer* or handout* or poster* or illustrat* or picture* or image* or pictorial* or pictogram*).tw.

39. exp Computer Applications/

40. exp Internet/

41. exp information technology/

42. exp computer applications/

43. information systems/

44. exp Computer Software/

45. computer assisted instruction/

46. (computer* adj1 (system* or network* or program* or terminal* or interface* or interact* or intervention* or graphic* or game* or simulation* or searching or mediated or based or tailored or communication or assisted)).tw.

47. (interactive adj3 (program* or software or online or on-line or media or technolog* or communication or health*)).tw.

48. exp Human Computer Interaction/

49. exp computer simulation/

50. exp graphical displays/

51. exp Computer Games/

52. video game*.tw.

53. decision making/

54. exp Decision Support Systems/

55. (decision adj (aid* or support or tool*)).tw.

56. exp counseling/

57. exp Foreign Language Translation/

58. multilingualism/

59. cultural* competen*.mp.

60. ((cultural* adj3 communication) or interpreter* or interpreting or translator* or translating).tw.

61. exp Medical Education/

62. (((continuing or residency or distance) adj2 education) or internship or interns or inservice or in-service or staff-development).mp.

63. or/15-62

64. 14 and 63

65. random*.ti,ab,hw,id.

66. trial*.ti,ab,hw,id.

67. control*.ti,ab,hw,id.

68. placebo*.ti,ab,hw,id.

69. ((singl* or doubl* or trebl* or tripl*) and (blind* or mask*)).ti,ab,hw,id.

70. (cross over or crossover or factorial* or latin square).ti,ab,hw,id.

71. (assign* or allocat* or volunteer*).ti,ab,hw,id.

72. or/65-71

73. 64 and 72

 

 

Appendix 4. CENTRAL (Cochrane Central Register of Controlled Trials), The Cochrane Library

 

 

 

Appendix 5. Data extraction sheet

 


IDENTIFICATION AND SUMMARY

Form version/date

Review titleINTERVENTIONS THAT PROMOTE INFORMED CONSENT FOR PATIENTS UNDERGOING SURGICAL AND INVASIVE PROCEDURES

Study IDSurname Year as it appears in RevMan

EligibilityYes = 1, No = 2

Reason for exclusion

Notes

Source of information

(esp if multiple reports of same trial, or unpublished data/personal communication included)

Aim of study

Aim of interventione.g. deliberation/recall/satisfaction/choice etc.

Study design

Informed consent for study1 = Yes, 2 = No, 3 = Unclear. Details if no.

Ethical approval1 = Yes, 2 = No, 3 = Unclear

Funding1 = Yes, 2 = No, 3 = Unclear. If yes, who? (not stated = no)

Outcomes measuredPrimary = x; Secondary = y.

a)  Selecting the primary outcome as identified by the publication authors

b)  If no primary outcome specified, select the one specified in the sample size calculation

c)  If there are no sample size calculations, rank the effect estimates and select the median effect estimate.

Outcomes relevant to our reviewPrimary outcomes  

1.Informed consent – all elements

Secondary outcomes  

2.1  Patient Outcomes

2.1.1        Patient understanding

2.1.2        Knowledge/Retention/Recall

2.1.3        Deliberation (Weighing up)

2.1.4        Communication of decision

2.1.5        Other patient outcomes

2.1.5.1  Satisfaction with decision making

2.1.5.2  Anxiety (or other psychological stress) with decision making

2.1.5.3  Satisfaction with consent process

2.1.5.4  Anxiety (or other psychological stress) with consent process

2.1.5.5  Desire for further information

2.1.5.6  Sense of control – locus of control or perception of who made the decision.

2.2  Clinician Outcomes

2.2.1        Satisfaction with the 'consent consultation'

2.2.2        Ease of use of intervention(s) to improve gaining of informed consent

2.2.3        Confidence in patient's decision and whether an informed choice was made

2.3  Systems outcome

2.3.1        Rates of uptake (or refusal) of clinical interventions/procedures

2.3.2        Postponement of clinical interventions/procedures

2.3.3        Delay in decision making or request for more information/further consultations

2.3.4        Complaints and litigation

2.3.5        Adverse outcomes

2.3.6        Economic/resource use data (e.g. length of consultations, cost of surgery/procedure choices, number of consultations, length of hospital stay)

Consumer involvement1 = Yes, 2 = No, 3 = Unclear (not mentioned = no)




BIAS –please refer to Cochrane Handbook chapter on bias which has definitions of low and high risk, see also  Table 1

Domain Review authors' judgement Description

Was the allocation sequence adequately generated?Yes/low risk of bias = 1

No/high risk of bias = 2

Unclear = 3

No information = 4
Describe the method used to generate the allocation sequence in sufficient detail to allow an assessment of whether it should produce comparable groups.

Was allocation adequately concealed?Yes/low risk of bias = 1

No/high risk of bias = 2

Unclear = 3

No information = 4
Describe the method used to conceal the allocation sequence in sufficient detail to determine whether intervention allocations could have been foreseen in advance of, or during, enrolment.

Blinding: Was knowledge of the allocation intervention adequately prevented during the study?

1) Blinding of participants and personnel?;

2) Blinding of outcome measurement
Yes/low risk of bias = 1

No/high risk of bias = 2

Unclear = 3

No information = 4
Describe all measures used, if any, to blind study participants and personnel from knowledge of which intervention a participant received. Also describe measures use to ensure measurement of outcomes was also blinded. Provide any information relating to whether the intended blinding was effective

Overall opinion on whether blinding was sufficient/suitable.

Were incomplete outcome data adequately addressed?Yes/low risk of bias = 1

No/high risk of bias = 2

Unclear = 3

No information = 4
Describe the completeness of outcome data for each main outcome, including attrition and exclusions from the analysis. State whether attrition and exclusions were reported, the numbers in each intervention group (compared with total randomized participants), reasons for attrition/exclusions where reported, and any re-inclusions in analyses performed by the review authors.

Rough estimate of 40% lost to follow up = high risk of bias (excludes legitimate reasons for drop out)

Are reports of the study free from suggestion of selective outcome reporting?Yes/low risk of bias = 1

No/high risk of bias = 2

Unclear = 3

No information = 4
State how the possibility of selective outcome reporting was examined by the review authors, and what was found.

5 min check for published protocol

Other sources of biasState any important concerns about bias not addressed in the other domains in the tool. If particular questions/entries were pre-specified in the review’s protocol, responses should be provided for each question/entry.Design of trial, contamination, fidelity/integrity, reliability of outcome, etc

Were the intervention and control groups comparable at baselineYes/low risk of bias = 1

No/high risk of bias = 2

Unclear = 3
In what way?

Have measures been taken within the study to protect against contamination?Yes/low risk of bias = 1

No/high risk of bias = 2

Unclear = 3

No information = 4

Other quality indicatorsNote: A potential source of bias must be able to change the magnitude of the effect estimate, whereas sources of imprecision affect only the uncertainty in the estimate (i.e. its confidence interval).  Potential factors affecting precision of an estimate include technological variability (e.g. measurement error), and observer variability.




PARTICIPANTS

Description(eg. Patients/consumers; carers; parents of patients/consumers; health professionals; well people in the community)

Geographical location and country(eg. City/State/Country) If unclear try to check, if still unclear assume location of first author

Setting(eg. Community, home, primary health centre, acute care hospital, extended care facility)

Inclusion criteria 

Exclusion criteria 

Invasive procedure undergone

Age+ range

Gender+ % male

Ethnicity

Social/demographic details(eg. Literacy or reading level)

Methods of recruitment of participants




Total eligible participants: 

Excluded 

RandomisedIntervention:

Control:

Withdrew 

Died 

Lost to follow-up 

Included in analysis

Total

Control

Intervention



 


INTERVENTIONS

Number of intervention groups

Number of control groups

Type of Intervention in studye.g. CD ROM, given lists of questions to ask etc.

Details of intervention

(Capture this information for each arm of the study, eg. Intervention A, Intervention B)
Theoretical basis (with key references); Content; Format(s) (media); Source; Setting  

Details of control/usual or routine care

Details of co-interventions in all groups(co-interventions may be separate to the intervention of interest for this review, or they may be other similar elements in a suite of interventions having a common purpose.  Record all relevant information).  i.e. above and beyond usual care

Delivery of intervention (eg. stages, timing, frequency, duration) (for each intervention included in the study, eg. Intervention A; Intervention B?)

Details of providers Who delivers the intervention?

Number of providers

Training of providers in delivery of intervention 

Intervention quality (if relevant): (record any information on the quality of the intervention  - assessed by study authors, others, or by you - such as the evidence base of the intervention, or the quality of staff training for intervention delivery)

Fidelity/integrityAdherence - Was the intervention delivered as intended?

Programme differentiation - received only the planned interventions

Exposure - number, length and frequency of implementation

Quality of delivery - implanter enthusiasm, attitude to intervention

Participant responsiveness - levels of participation and enthusiasm

Record any assessment of this



 


OUTCOME 1

Power calculation performed?1 = Yes, 2 = No, 3 = Unclear + who did it


Sample size calculated achieved?1 = Yes, 2 = No, 3 = Unclear, 4 = NA


Confounding?State potential confounders and if this controlled for in analysis?


Outcome Measure 1:


Methods of assessing outcome measure(eg. phone survey, questionnaire, physical measurements (for each outcome))


Method of follow-up for non-respondents


Timing of outcome assessment(including frequency, length of follow up (for each outcome)) 


Interpretation of scale scores


Adverse events(eg. complaints, levels of dissatisfaction, adverse incidents, side effects)


Statistical analysis performede.g. t-test, ANOVA, ANCOVA, linear regression (for continuous data); Chi2, logistic regression (for dichotomous outcomes); Mann-Whitney (ordinal data).


Were outcome measurement tools validated?Yes = 1

No = 2

Unclear = 3
Methods of validation/supporting literature



Are the outcome measures reliable?Yes = 1

No = 2

Unclear = 3

No information = 4
Test re-test – proven with supporting literature?



 


Dichotomous outcomes

OutcomeTiming of outcome assessmentIntervention groupControl groupP values, CIs, Notes


Observed (n)Total (N)Observed (n)Total (N)







 







 







 







 

 







Continuous outcomes

OutcomeTiming of outcome assessmentIntervention groupControl groupP values, CIs, Notes


Mean/mean changeStandard deviationNMean/mean changeStandard deviationN









 









 



 


Non-parametric outcomes

OutcomeTiming of outcome assessmentIntervention groupControl groupNotes


MedianInter-quartile rangeNMedianInter-quartile rangeN

 

 




OUTCOME 2

Power calculation performed?1 = Yes, 2 = No, 3 = Unclear + who did it


Sample size calculated achieved?1 = Yes, 2 = No, 3 = Unclear, 4 = NA


Confounding?State potential confounders and if this controlled for in analysis?


Outcome Measure 2:


Methods of assessing outcome measure(eg. Phone survey, questionnaire, physical measurements (for each outcome))


Method of follow-up for non-respondents


Timing of outcome assessment(including frequency, length of follow up (for each outcome)) 


Interpretation of scale scores



Adverse events(eg. Complaints, levels of dissatisfaction, adverse incidents, side effects)


Statistical analysis performede.g. t-test, ANOVA, ANCOVA, linear regression (for continuous data); Chi2, logistic regression (for dichotomous outcomes); Mann-Whitney (ordinal data).


Were outcome measurement tools validated?Yes = 1

No = 2

Unclear = 3
Methods of validation/supporting literature 




Are the outcome measures reliable?Yes = 1

No = 2

Unclear = 3

No information = 4
Test re-test – proven with supporting literature? 



 

 


Dichotomous outcomes

OutcomeTiming of outcome assessmentIntervention groupControl groupP values, CIs, Notes


Observed (n)Total (N)Observed (n)Total (N)







 







 

 







 

 







 







Continuous outcomes

OutcomeTiming of outcome assessmentIntervention groupControl groupP values, CIs, Notes


Mean/mean changeStandard deviationNMean/mean changeStandard deviationN









  









 



 


Non-parametric outcomes

OutcomeTiming of outcome assessmentIntervention groupControl groupNotes


MedianInter-quartile rangeNMedianInter-quartile rangeN

  

  



 


OUTCOME 3

Power calculation performed?1 = Yes, 2 = No, 3 = Unclear + who did it


Sample size calculated achieved?1 = Yes, 2 = No, 3 = Unclear, 4 = NA


Confounding?State potential confounders and if this controlled for in analysis?


Outcome Measure 3:


Methods of assessing outcome measure(eg. Phone survey, questionnaire, physical measurements (for each outcome))


Method of follow-up for non-respondents


Timing of outcome assessment(including frequency, length of follow up (for each outcome)) 


Interpretation of scale scores



Adverse events(eg. Complaints, levels of dissatisfaction, adverse incidents, side effects)


Statistical analysis performede.g. t-test, ANOVA, ANCOVA, linear regression (for continuous data); Chi2, logistic regression (for dichotomous outcomes); Mann-Whitney (ordinal data).


Were outcome measurement tools validated?Yes = 1

No = 2

Unclear = 3
Methods of validation/supporting literature 




Are the outcome measures reliable?Yes = 1

No = 2

Unclear = 3

No information = 4
Test re-test – proven with supporting literature? 



 


Dichotomous outcomes

OutcomeTiming of outcome assessmentIntervention groupControl groupP values, CIs, Notes


Observed (n)Total (N)Observed (n)Total (N)







 







 







 







 

 







Continuous outcomes

OutcomeTiming of outcome assessmentIntervention groupControl groupP values, CIs, Notes


Mean/mean changeStandard deviationNMean/mean changeStandard deviationN









 









 



 


Non-parametric outcomes

OutcomeTiming of outcome assessmentIntervention groupControl groupNotes


MedianInter-quartile rangeNMedianInter-quartile rangeN

 

 




The studies’ key conclusions

References to other studies

Eg Contact with author, if study translated, if study duplicate publication



 

Contributions of authors

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. Contributions of authors
  12. Declarations of interest
  13. Sources of support
  14. Differences between protocol and review
  15. Index terms

Glyn Elwyn, Paul Kinnersley, Bethan Stephens, Adrian Edwards and Jane Blazeby were involved in conceiving the idea for the review. Mala Mann supervised the search strategy. Katie Phillips and Katherine Savage led the searching, data extraction and analyses with Ben Morgan, Elinor Farrell, Vicky Lewis and Robert Whistance. Mark Kelly provided statistical expertise. All the authors were involved in the consideration and interpretation of the results. Katie Phillips, Katherine Savage, Adrian Edwards and Paul Kinnersley produced the final report. 

 

Declarations of interest

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. Contributions of authors
  12. Declarations of interest
  13. Sources of support
  14. Differences between protocol and review
  15. Index terms

Glyn Elwyn, Adrian Edwards, Paul Kinnersley have been involved in the evaluation of decision aids. None of the authors have any financial interest in the results of the review.

 

Sources of support

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. Contributions of authors
  12. Declarations of interest
  13. Sources of support
  14. Differences between protocol and review
  15. Index terms
 

Internal sources

  • School of Medicine, Cardiff University, UK.
    Infrastructure and salary support to Kinnersley, Elwyn, Stephens, Savage, Lewis, Edwards and Kelly.
  • School of Social and Community Medicine, Bristol University, UK.
    Infrastructure and salary support to Blazeby.
  • Support Unit for Research Evidence, Cardiff University, UK.
    Infrastructure and salary support to Mann.

 

External sources

  • NIHR, UK.
    Whistance holds a Doctoral Research Fellowship award

 

Differences between protocol and review

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. Contributions of authors
  12. Declarations of interest
  13. Sources of support
  14. Differences between protocol and review
  15. Index terms

The protocol (Kinnersley 2011) and the review differ in the following ways:

  • We developed three timeframes for the outcome 'knowledge'. and categorised results into immediate, short-term and long-term assessments for this outcome.
  • The subgroup analyses of face-to-face versus distant intervention use, classification of intervention and timing of intervention were developed post-hoc.
  • Our approach diverged from that stated in the protocol by presenting meta-analyses including those with high heterogeneity, and including non-parametric data in results, in a comprehensive approach.
  • Finally, Katie Phillips, Katherine Savage, Ben Morgan, Elinor Farrell, Vicky Lewis and Robert Whistance joined the review team after the protocol was completed.

References

References to studies included in this review

  1. Top of page
  2. Abstract
  3. Background
  4. Objectives
  5. Methods
  6. Results
  7. Discussion
  8. Authors' conclusions
  9. Acknowledgements
  10. Data and analyses
  11. Appendices
  12. Contributions of authors
  13. Declarations of interest
  14. Sources of support
  15. Differences between protocol and review
  16. Characteristics of studies
  17. References to studies included in this review
  18. References to studies excluded from this review
  19. Additional references
  20. References to other published versions of this review
Agre 1994a {published data only}
  • Agre P, Kurtz RC, Krauss BJ. A randomized trial using videotape to present consent information for colonoscopy. Gastrointestinal Endoscopy 1994;40(3):271-6.
Agre 1994b {published data only}
  • Agre P, Kurtz RC, Krauss BJ. A randomized trial using videotape to present consent information for colonoscopy. Gastrointestinal Endoscopy 1994;40(3):271-6.
Armstrong 1997 {published data only (unpublished sought but not used)}
Armstrong 2010 {published and unpublished data}
Ashraff 2006 {published data only (unpublished sought but not used)}
Astley 2008a {published data only}
  • Astley CM, Chew DP, Aylward PE, Molloy DA, De Pasquale CG. A randomised study of three different Informational aids prior to coronary angiography, measuring patient recall, satisfaction and anxiety. Heart Lung and Circulation 2008;17(1):25-32.
Astley 2008b {published data only}
  • Astley CM, Chew DP, Aylward PE, Molloy DA, De Pasquale CG. A randomised study of three different informational aids prior to coronary angiography, measuring patient recall, satisfaction and anxiety. Heart Lung and Circulation 2008;17(1):25-32.
Bekker 2004 {published and unpublished data}
Bennett 2009a {published data only (unpublished sought but not used)}
  • Bennett DL, Dharia CV, Ferguson KJ, Okon AE. Patient-physician communication: informed consent for imaging-guided spinal injections. Journal of the American College of Radiology 2009;6(1):38-44.
Bennett 2009b {published data only (unpublished sought but not used)}
  • Bennett DL, Dharia CV, Ferguson KJ, Okon AE. Patient-physician communication: informed consent for imaging-guided spinal injections. Journal of the American College of Radiology 2009;6(1):38-44.
Bollschweiler 2008 {published data only (unpublished sought but not used)}
  • Bollschweiler E, Apitzsch J, Obliers R. Results of a prospective randomized multicenter study of patients before cholecystectomy. Annals of Surgery 2008;248(4):694.
Chan 2002 {published data only (unpublished sought but not used)}
  • Chan Y, Irish JC, Wood SJ, Rotstein LE, Brown DH, Gullane PJ, et al. Patient education and informed consent in head and neck surgery. Archives of Otolaryngology - Head and Neck Surgery 2002;128(11):1269-74.
Chantry 2010 {published data only}
Cornoiu 2010a {published and unpublished data}
Cornoiu 2010b {published and unpublished data}
Cowan 2007 {published and unpublished data}
  • Cowan EA, Calderon Y, Gennis P, Macklin R, Ortiz C, Wall SP. Spanish and English video-assisted informed consent for intravenous contrast administration in the emergency department: a randomized controlled trial. Annals of Emergency Medicine 2007;49(2):221-30.
Danino 2006 {published data only}
  • Danino AM, Sultan SD, Weber ID, Herve C, Malka G. Effect of information by images on patients' anxiety and comprehension before esthetic surgery on the abdominal wall: a prospective randomised trial with 60 patients [Impact de l'introduction d'images sur l'anxiete et la connaissance des patientes avant une abdominoplastie esthetique: Une etude prospective randomisee incluant 60 patientes]. Annales de Chirurgie Plastique et Esthetique 2006;51(6):517-24.
Deyo 2000 {published data only (unpublished sought but not used)}
  • Deyo RA, Cherkin DC, Weinstein J, Howe J, Ciol M, Mulley Jr AG. Involving patients in clinical decisions: impact of an interactive video program on use of back surgery. Medical Care 2000;38(9):959-69.
Elfant 1995 {published data only (unpublished sought but not used)}
Enzenhofer 2004 {published data only}
  • Enzenhofer M, Bludau HB, Komm N, Wild B, Mueller K, Herzog W, et al. Improvement of the educational process by computer-based visualization of procedures: randomized controlled trial. Journal of Medical Internet Research 2004;6(2):e16.
Felley 2008 {published data only}
  • Felley C, Perneger TV, Goulet I, Rouillard C, Azar-Pey N, Dorta G, et al. Combined written and oral information prior to gastrointestinal endoscopy compared with oral information alone: a randomized trial. BMC Gastroenterology 2008;8(22):n.p. [DOI: 10.1186/1471-230X-8-22]
Fink 2010 {published and unpublished data}
  • Fink AS, Prochazka AV, Henderson WG, Bartenfeld D, Nyirenda C, Webb A, et al. Enhancement of surgical informed consent by addition of repeat back: a multicenter, randomized controlled clinical trial. Annals of Surgery 2010;252(1):27-36.
Friedlander 2011 {published data only}
  • Friedlander JA, Loeben GS, Finnegan PK, Puma AE, Zhang X, de Zoeten EF, et al. A novel method to enhance informed consent: a prospective and randomised trial of form-based versus electronic assisted informed consent in paediatric endoscopy. Journal of Medical Ethics 2011;37(4):194-200.
Garden 1996 {published and unpublished data}
  • Garden AL, Merry AF, Holland RL, Petrie KJ. Anaesthesia information - what patients want to know. Anaesthesia and Intensive Care 1996;24(5):594-8.
Garrud 2001 {published data only (unpublished sought but not used)}
  • Garrud P, Wood M, Stainsby L. Impact of risk information in a patient education leaflet. Patient Education and Counseling 2001;43(3):301-4.
Gerancher 2000 {published data only (unpublished sought but not used)}
  • Gerancher JC, Grice SC, Dewan DM, Eisenach J. An evaluation of informed consent prior to epidural analgesia for labor and delivery. International Journal of Obstetric Anesthesia 2000;9(3):168-73.
Goel 2001 {published data only (unpublished sought but not used)}
  • Goel V, Sawka CA, Thiel EC, Gort EH, O'Connor AM. Randomized trial of a patient decision aid for choice of surgical treatment for breast cancer. Medical Decision Making 2001;21:1-6.
Greening 1999 {published data only (unpublished sought but not used)}
  • Greening J, Bentham P, Stemman J, Staples V, Ambegaokar S, Upthegrove R, et al. The effect of structured consent on recall of information pre- and post-electroconvulsive therapy: a pilot study. Psychiatric Bulletin 1999;23(8):471-4.
Heller 2008 {published data only (unpublished sought but not used)}
Henry 2008 {published data only (unpublished sought but not used)}
  • Henry E, Brown T, Bartlett C, Massoud E, Bance M. Informed consent in otologic surgery: Prospective randomized study comparing risk recall with an illustrated handout and a nonillustrated handout. Journal of Otolaryngology - Head and Neck Surgery 2008;37(2):273-8.
Hermann 2002 {published data only}
  • Hermann M. 3-dimensional computer animation--a new medium for supporting patient education before surgery Acceptance and assessment of patients based on a prospective randomized study--picture versus text [Dreidimensionale Computeranimation--neues Medium zur Unterstutzung des Aufklarungsgesprachs vor Operationen Akzeptanz und Bewertung der Patienten anhand einer prospektiv randomisierten Studie--Bild versus Text]. Der Chirurg; Zeitschrift fur alle Gebiete der operativen Medizen 2002;73(5):500-7.
Hong 2009 {published data only}
  • Hong P, Makdessian AS, Ellis DAF, Taylor SM. Informed consent in rhinoplasty: prospective randomized study of risk recall in patients who are given written disclosure of risks versus traditional oral discussion groups. Journal of Otolaryngology - Head and Neck Surgery 2009;38(3):369-74.
Hopper 1994 {published data only}
  • Hopper KD, Zajdel M, Hulse SF, Yoanidis NR, TenHave TR, Labuski MR, et al. Interactive method of informing patients of the risks of intravenous contrast media. Radiology 1994;192(1):67-71.
Johnson 2006 {published data only (unpublished sought but not used)}
  • Johnson BR, Schartz A, Goldberg J, Koerber A. A chairside aid for shared decision making in dentistry: a randomized controlled trial. Journal of Dental Education 2006 Feb;70(2):133-41.
Kain 1997 {published and unpublished data}
  • Kain ZN, Wang SM, Caramico LA, Hofstadter M, Mayes LC. Parental desire for perioperative information and informed consent: a two-phase study. Anesthesia and Analgesia 1997;84(2):299-306.
Kang 2009a {published and unpublished data}
  • Kang EY, Fields HW, Kiyak A, Beck FM, Firestone AR. Informed consent recall and comprehension in orthodontics: traditional vs improved readability and processability methods. American Journal of Orthodontics and Dentofacial Orthopedics 2009;136(4):488.e1-e13.
Kang 2009b {published and unpublished data}
  • Kang EY, Fields HW, Kiyak A, Beck FM, Firestone AR. Informed consent recall and comprehension in orthodontics: traditional vs improved readability and processability methods. American Journal of Orthodontics and Dentofacial Orthopedics 2009;136(4):488.e1-e13.
Langdon 2002 {published data only}
  • Langdon IJ, Hardin R, Learmonth ID. Informed consent for total hip arthroplasty: does a written information sheet improve recall by patients?. Annals of the Royal College of Surgeons of England 2002;84(6):404-8.
Lavelle-Jones 1993 {published data only (unpublished sought but not used)}
  • Lavelle-Jones C, Byrne DJ, Rice P, Cuschieri A. Factors affecting quality of informed consent. BMJ 1993;306(6882):885-90.
Luck 1999 {published and unpublished data}
Makdessian 2004 {published data only}
  • Makdessian AS, Ellis DA, Irish JC. Informed consent in facial plastic surgery: effectiveness of a simple educational intervention. Archives of Facial Plastic Surgery 2004;6(1):26-30.
Mason 2003 {published data only}
  • Mason V, McEwan A, Walker D, Barrett S, James D. The use of video information in obtaining consent for female sterilisation: a randomised study. British Journal of Obstetrics and Gynaecology 2003;110(12):1062-71.
Masood 2007 {published data only (unpublished sought but not used)}
Mauffrey 2008 {published and unpublished data}
  • Mauffrey C, Prempeh EM, John J, Vasario G. The influence of written information during the consenting process on patients' recall of operative risks: a prospective randomised study. International Orthopaedics 2008;32(4):425-9.
Mishra 2010a {published and unpublished data}
  • Mishra PK, Mathias H, Millar K, Nagrajan K, Murday A. A randomized controlled trial to assess the effect of audiotaped consultations on the quality of informed consent in cardiac surgery. Archives of Surgery 2010;145(4):383-8.
Mishra 2010b {published and unpublished data}
  • Mishra PK, Mathias H, Millar K, Nagrajan K, Murday A. A randomized controlled trial to assess the effect of audiotaped consultations on the quality of informed consent in cardiac surgery. Archives of Surgery 2010;145(4):383-8.
Morgan 2000 {published and unpublished data}
  • Morgan MW, Deber RB, Llewellyn-Thomas HA, Gladstone P, Cusimano RJ, O'Rourke K, et al. Randomized, controlled trial of an interactive videodisc decision aid for patients with ischemic heart disease. Journal of General Internal Medicine 2000;15(10):685-93.
Nadeau 2010 {published and unpublished data}
  • Nadeau DP, Rich JN, Brietzke SE. Informed consent in pediatric surgery: do parents understand the risks?. Archives of Otolaryngology - Head and Neck Surgery 2010;136(3):265-9.
Neary 2010 {published data only}
  • Neary PM, Sung R, Corrigan M, O'Donovan M, Cahill RA, Redmond HP. The benefits of an interactive, individualized online patient pathway for patients undergoing minimally invasive radioguided parathyroidectomy: a prospective, double-blinded, randomized clinical trial. Surgical Innovation 2010;17(3):236-41.
Neptune 1996 {published data only (unpublished sought but not used)}
O'Neill 1996a {published data only}
O'Neill 1996b {published data only}
Olver 2009 {published and unpublished data}
  • Olver IN, Whitford HS, Denson LA, Peterson MJ, Olver SI. Improving informed consent to chemotherapy: a randomized controlled trial of written information versus an interactive multimedia CD-ROM. Patient Education and Counseling 2009;74(2):197-204.
Paci 1999 {published data only}
  • Paci E, Barneschi MG, Miccinesi G, Falchi S, Metrangolo L, Novelli GP. Informed consent and patient participation in the medical encounter: a list of questions for an informed choice about the type of anaesthesia. European Journal of Anaesthesiology 1999;16(3):160-5.
Pesudovs 2006 {published data only (unpublished sought but not used)}
  • Pesudovs K, Luscombe CK, Coster DJ. Recall from informed consent counselling for cataract surgery. Journal of Law and Medicine 2006;13(4):496-504.
Phatouros 1995 {published data only (unpublished sought but not used)}
  • Phatouros CC, Blake MP. Patients' attitudes to an information sheet prior to angiography and angioplasty. Australasian Radiology 1995;39(2):135-9.
Raynes-Greenow 2010 {published data only}
  • Raynes-Greenow CH, Nassar N, Torvaldsen S, Trevena L, Roberts CL. Assisting informed decision making for labour analgesia: a randomised controlled trial of a decision aid for labour analgesia versus a pamphlet. BMC Pregnancy and Childbirth 2010;10(15). [DOI: 10.1186/1471-2393-10-15]
Rossi 2004 {published data only (unpublished sought but not used)}
  • Rossi M, McClellan R, Chou L, Davis K. Informed consent for ankle fracture surgery: patient comprehension of verbal and videotaped information. Foot and Ankle International 2004;25(10):756-62.
Rossi 2005 {published data only (unpublished sought but not used)}
Rymeski 2010 {published data only}
  • Rymeski B, Marchildon M, Katz DA, Vinocur CD, Dunn SP, Reichard KW, et al. Pilot study using an Internet-based program in informed consent. Journal of Pediatric Surgery 2010;45(6):1137-41.
Shorten 2005 {published data only}
Solberg 2010 {published data only}
  • Solberg LI, Asche SE, Sepucha K, Thygeson NM, Madden JE, Morrissey L, et al. Informed choice assistance for women making uterine fibroid treatment decisions: a practical clinical trial. Medical Decision Making 2010;30(4):444-52.
Tait 2009 {published and unpublished data}
  • Tait AR, Voepel-Lewis T, Moscucci M, Brennan-Martinez CM, Levine R. Patient comprehension of an interactive, computer-based information program for cardiac catheterization: a comparison with standard information. Archives of Internal Medicine 2009;169(20):1907-14.
Thomas 2000 {published data only}
  • Thomas R, Daly M, Perryman B, Stockton D. Forewarned is forearmed - benefits of preparatory information on video cassette for patients receiving chemotherapy or radiotherapy - a randomised controlled trial. European Journal of Cancer 2000;36(12):1536-43.
Uzbeck 2009 {published data only (unpublished sought but not used)}
  • Uzbeck M, Quinn C, Saleem I, Cotter P, Gilmartin JJ, O'Keeffe ST. Randomised controlled trial of the effect of standard and detailed risk disclosure prior to bronchoscopy on peri-procedure anxiety and satisfaction. Thorax 2009;64(3):224-7.
Wadey 1997 {published data only}
Walker 2007 {published data only}
  • Walker MS, Farria D, Schmidt M, Monsees B, Wiele K, Bokern J, et al. Educational intervention for women undergoing image-guided breast biopsy: results of a randomized clinical trial. Cancer Control 2007;14(4):380-7.
Whelan 2003 {published data only (unpublished sought but not used)}
  • Whelan T, Sawka C, Levine M, Gafni A, Reyno L, Willan A, et al. Helping patients make informed choices: a randomized trial of a decision aid for adjuvant chemotherapy in lymph node-negative breast cancer. Journal of the National Cancer Institute 2003;95(8):581-7.
Wilhelm 2009 {published and unpublished data}
  • Wilhelm D, Gillen S, Wirnhier H, Kranzfelder M, Schneider A, Schmidt A, et al. Extended preoperative patient education using a multimedia DVD-impact on patients receiving a laparoscopic cholecystectomy: a randomised controlled trial. Langenbeck's Archives of Surgery 2009;394(2):227-33.
Wong 2006 {published data only}
Yucel 2005 {published data only}
  • Yucel A, Gecici O, Emul M, Oyar O, Gulsoy UK, Dayanir YO, et al. Effect of informed consent for intravascular contrast material on the level of anxiety: how much information should be given?. Acta Radiologica 2005;46(7):701-7.
Zite 2011 {published data only}
  • Zite NB, Wallace LS. Use of a low-literacy informed consent form to improve women's understanding of tubal sterilization: a randomized controlled trial. Obstetrics and Gynecology 2011;117(5):1160-6.

References to studies excluded from this review

  1. Top of page
  2. Abstract
  3. Background
  4. Objectives
  5. Methods
  6. Results
  7. Discussion
  8. Authors' conclusions
  9. Acknowledgements
  10. Data and analyses
  11. Appendices
  12. Contributions of authors
  13. Declarations of interest
  14. Sources of support
  15. Differences between protocol and review
  16. Characteristics of studies
  17. References to studies included in this review
  18. References to studies excluded from this review
  19. Additional references
  20. References to other published versions of this review
Ader 1992 {published data only}
  • Ader DN, Seibring AR, Bhaskar P, Melamed BG. Information seeking and interactive videodisc preparation for third molar extraction. Journal of Oral & Maxillofacial Surgery 1992;50(1):27-31; discussion -2.
Altaie 2011 {published data only}
  • Altaie RR, Ku JJ, Mora JJ. Informed consent in strabismus surgery. Journal of American Association of Pediatric Ophthalmology and Strabismus 2011;15(1):e12.
Broyles 1992 {published data only}
Clark 2011 {published data only}
  • Clark S, Mangram A, Ernest D, Lebron R, Peralta L. The informed consent: a study of the efficacy of informed consents and the associated role of language barriers. Journal of Surgical Education 2011;68(2):143-7.
Dawes 1992 {published data only}
  • Dawes PJ, O'Keefe L, Adcock S. Informed consent: the assessment of two structured interview approaches compared to the current approach. Journal of Laryngology & Otology 1992;106(5):420-4.
Dawes 1993 {published data only}
  • Dawes PJD, O'Keefe L, Adcock S. Informed consent: using a structured interview changes patients' attitudes towards informed consent. Journal of Laryngology and Otology 1993;107(9):775-9.
Eggers 2007 {published data only}
Finch 2009 {published data only}
  • Finch WJG, Rochester MA, Mills RD. A randomised trial of conventional versus BAUS procedure-specific consent forms for transurethral resection of prostate. Annals of the Royal College of Surgeons of England 2009;91(3):232-8.
Fink 2010a {published data only}
  • Fink AS, Prochazka AV, Henderson WG, Bartenfeld D, Nyirenda C, Webb A, et al. Enhancement of surgical informed consent by addition of repeat back: a multicenter, randomized controlled clinical trial. Annals of Surgery 2010;252(1):27-36.
Graham 2000 {published data only}
  • Graham W, Smith P, Kamil A, Fitzmaurice A, Smith N, Hamilton N. Randomised controlled trial comparing effectiveness of touchscreen system with leaflet for providing women with information on prenatal tests. BMJ 2000;320:155-60.
Grawe 2010 {published data only}
  • Grawe JS, Mirow L, Bouchard R, Lindig M, Huppe M. [Impact of preoperative patient education on postoperative pain in consideration of the individual coping style]. Der Schmerz 2010;24(6):575-86.
Gyomber 2010 {published data only}
Hewison 2001 {published data only}
  • Hewison J, Cuckle H, Baillie C, Sehmi I, Lindow S, Jackson F, et al. Use of videotapes for viewing at home to inform choice in Down syndrome screening: a randomised controlled trial. Prenatal Diagnosis 2001;21(2):146-9.
Hilzenrat 2006 {published data only}
  • Hilzenrat N, Yesovitch R, Shrier I, Stavrakis M, Deschenes M. The effect of information level and coping style on pain and anxiety in needle liver biopsy. Canadian Journal of Gastroenterology 2006;20(9):597-600.
Jlala 2010 {published data only}
  • Jlala HA, French JL, Foxall GL, Hardman JG, Bedforth NM. Effect of preoperative multimedia information on perioperative anxiety in patients undergoing procedures under regional anaesthesia. British Journal of Anaesthesia 2010;104(3):369-74.
Johnson 2011 {published data only}
  • Johnson MR, Singh JA, Stewart T, Terance JG. Patient understanding and satisfaction in informed consent for total knee arthroplasty: a randomized study. American College of Rheumatology July 2011;63(7):1048-54.
Kasper 2008 {published data only}
Lembcke 1998 {published data only}
  • Lembcke B, Specht J, Nippel G, Caspary WF. Prospective randomized investigation of three printed information forms for upper GI-endoscopy [Struktur- und ergebnisqualitat deutschsprachiger gastroskopie- aufkdarungsbogen aus Patientensicht]. Zeitschrift fur Gastroenterologie 1998;36(9):829-38.
Lipp 1991 {published data only}
  • Lipp M, Dick W, Daublander M, Bertram M. Different information patterns and their influence on patient anxiety prior to dental local anesthesia [Beeinflussung der Patientenangst vor der zahnarztlichen Lokalanasthesie mit verschiedenen Aufklarungsformen]. Deutsche Zeitschrift fur Mund-, Kiefer- und Gesichts-Chirurgie 1991;15(6):449-57.
Migden 2008 {published data only}
  • Migden M, Chavez-Frazier A, Nguyen T. The use of high definition video modules for delivery of informed consent and wound care education in the Mohs Surgery Unit. Seminars in Cutaneous Medicine and Surgery 2008;27(1):89-93.
Nagle 2008 {published data only}
O'Cathain 2002 {published data only}
  • O'Cathain A, Walters SJ, Nicholl JP, Thomas KJ, Kirkham M. Use of evidence based leaflets to promote informed choice in maternity care: randomised controlled trial in everyday practice. BMJ 2002;324(7338):643-6.
Roth-Isigkeit 2001a {published data only}
  • Roth-Isigkeit A, Brechmann J, Schwarzenberger J, Bruckner S, Schmucker P. Preoperative preparation of patients undergoing cardiac surgery and satisfaction ratings [Auswirkungen praoperativer vorbereitung auf zufriedenheitseinschatzungen kardiochirurgischer patienten]. Zeitschrift fur Herz-, Thorax- und Gefasschirurgie 2001;15(2):62-7.
Scanlan 2003 {published data only}
  • Scanlan D, Siddiqui F, Perry G, Hutnik CML. Informed consent for cataract surgery: what patients do and do not understand. Journal of Cataract and Refractive Surgery 2003;29(10):1904-12.
Schenker 2010 {published data only}
  • Schenker Y. Computer information program improves patient understanding in informed consent for cardiac catheterization. Journal of Clinical Outcomes Management 2010;17(1):10-2.
Shurnas 2003 {published data only}
  • Shurnas PS, Coughlin MJ. Recall of the risks of forefoot surgery after informed consent. Foot and Ankle International 2003;24(12):904-8.
Stanley 1998 {published data only}
Steckelberg 2011 {published data only}
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Wright 2010 {published data only}
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Additional references

  1. Top of page
  2. Abstract
  3. Background
  4. Objectives
  5. Methods
  6. Results
  7. Discussion
  8. Authors' conclusions
  9. Acknowledgements
  10. Data and analyses
  11. Appendices
  12. Contributions of authors
  13. Declarations of interest
  14. Sources of support
  15. Differences between protocol and review
  16. Characteristics of studies
  17. References to studies included in this review
  18. References to studies excluded from this review
  19. Additional references
  20. References to other published versions of this review
Akkad 2004
Akkad 2006
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Beisecker 1990
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Brezis 2008
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CCCRG 2008
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Edwards 2002
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References to other published versions of this review

  1. Top of page
  2. Abstract
  3. Background
  4. Objectives
  5. Methods
  6. Results
  7. Discussion
  8. Authors' conclusions
  9. Acknowledgements
  10. Data and analyses
  11. Appendices
  12. Contributions of authors
  13. Declarations of interest
  14. Sources of support
  15. Differences between protocol and review
  16. Characteristics of studies
  17. References to studies included in this review
  18. References to studies excluded from this review
  19. Additional references
  20. References to other published versions of this review
Kinnersley 2011
  • Kinnersley P, Stephens BL, Elwyn GJ, Blazeby J, Kelly MJ, Savage K, et al. Interventions to promote informed consent for patients undergoing surgical and other invasive healthcare procedures. Cochrane Database of Systematic Reviews 2011, Issue 11. [DOI: 10.1002/14651858.CD009445]