Physician anaesthetists versus non-physician providers of anaesthesia for surgical patients

  • Protocol
  • Intervention

Authors


Abstract

This is the protocol for a review and there is no abstract. The objectives are as follows:

We wish to assess the safety and effectiveness of different anaesthetic providers for patients undergoing surgical procedures under general, regional or epidural anaesthetic. A subsidiary question is to determine whether there are types of procedures or patient groups for which a non-physician anaesthetist is not appropriate. We will consider results from studies within different regions (US, UK, other developed countries and developing countries) initially and then assess whether results are consistent across regions before combining results.

Background

Internationally there are challenges for the provision of anaesthetic services. Current and predicted shortfalls can be explained by an ageing population, increasing demand for surgery, changes to working hours, migration of anaesthetists, pressure on healthcare costs and in some countries a reduction in the number of medical graduates choosing to specialise in anaesthesia (Egger 2006; Egger 2007; Jordan 2011).

Similar pressures are seen in other fields of health care, resulting in a trend towards the use of a nurse-led rather than a traditional doctor-led service, such as in primary care and monitoring of long term conditions. However, the development of similar substitutions within the field of anaesthesia has been met with more resistance (Smith 2005).

With regard to cost containment, there is a substantial difference in the salaries of the two personnel within countries (in the United States (US), for example, the salary difference of an anaesthetist is approximately double that of non-physician personnel (Kalist 2011)). 

Role of non-physician anaesthetist

For the purpose of this review, and to avoid confusion, the word 'physician anaesthetist' will be used for all personnel who are medically qualified, and 'non-physician anaesthetist' (NPA) for all those who provide anaesthesia without a medical qualification. This includes a change of terms for discussion regarding some countries, for example in the US they are normally referred to as 'anesthesiologists' and 'Certified Registered Nurse Anesthetists' (or CRNAs), respectively. 

There are considerable differences in the organisation of anaesthetic teams across Europe and internationally (Egger 2007; Meeusen 2010), where anaesthetics may be administered by physician anaesthetists working alone or as part of an anaesthetic team, or by NPAs who in turn may be working alone or as part of an anaesthetic team (Bacon 2002). Between countries there are also significant differences in the length of training of personnel (Egger 2007; Matsusaki 2011; Meeusen 2010).

Non-physician anaesthetist in developing countries

Low and middle income countries, with large populations living in rural locations, have few physician anaesthetists with ratios of less than one per 100,000 population. For example, Uganda has approximately one physician anaesthetist per two million population (Dubowitz 2010) as opposed to the UK which has 12,000 per 64 million, that is 1: 5000 (Walker 2007). These countries have been using non-physician personnel to deliver many anaesthetic services, for example Kenya’s nurse anaesthesia training programme (Newton 2010).

Non-physician anaesthetist in the US

The US has a long history of using nurses to administer anaesthetics. However, as anaesthesia developed as a physician specialty there is now a majority of medically qualified anaesthetists and considerable debate exists between the two professional groups regarding roles and responsibilities (Bacon 2002; Gardner 2011; Matsusaki 2011). Kalist 2011 says “there is so much overlap between the work they do that it is not clear whether an MDA (physician anaesthetist) actually does anything that a CRNA (NPA) does not do”. In recent years, changes to state law in the US with regard to Medicare and Medicaid reimbursement allow some NPAs to now practice without supervision from a physician anaesthetist. At present there are 17 states who have 'opted out' and can practice as such (AANA Fact Sheet). Millions of dollars have been spent lobbying for or against this ruling (Bacon 2002).

Non-physician anaesthetists in the UK and other developed countries

The UK, along with several other countries, continues to resist a move towards unsupervised NPAs. The introduction of an anaesthesia physician assistant (now called physician assistant (anaesthesia) or PA(A)) pilot training programme from October 2003 attempted to address the predicted shortfall of physician anaesthetists (Wilkinson 2007). However, there are limits to the responsibilities given to a PA(A) and they are provided with supervision from a physician anaesthetist. After the introduction of PA(A)s, the Association of Anaesthetists of Great Britain and Ireland maintains an opinion that “the highest standards of anaesthesia can only be achieved by a physician-only service” (AAGBI 2010).

Despite differences in opinion regarding the length of training of NPAs in some countries, the potential benefits of independent practice are evident, particularly in rural areas which attract fewer anaesthetists.

Impact of use of non-physician anaesthetists on patient care

The debate over the use of non-physician anaesthetists has focused on patient safety and the question of whether different providers deliver equivalent quality and safety to patients.

A systematic review has been carried out by Smith, Kane and Milne (Smith 2004). They identified four articles relevant to the review question, none of which were randomized controlled trials (RCTs). They were unable to show any significant difference in the safety of using different anaesthetic providers, however they also concluded that, given the methodological flaws in the available studies, this was not evidence of absence of a difference.

Apart from anxieties over patient safety, there are other factors involved in how far the role of an NPA should be developed, such as threats to medically qualified physician anaesthetists’ professional status, access to training and working practices, as well as the wish to avoid the costly and lengthy interprofessional conflict that exists in the US (Kane 2004; Smith 2005).

Why it is important to do this review

Increasing demands on healthcare systems together with a predicted personnel shortfall and the current emphasis on cost containment make this a timely and important review.   

We aim to update Smith’s existing review (Smith 2004), adding in RCTs if they exist. Our aim is to establish what is known about patient safety when anaesthetics are administered by different personnel. This may lead to an increase in confidence in the skills of NPAs within the anaesthetic community and may potentially lead to greater flexibility in team roles both within and between countries depending on patient need.

Objectives

We wish to assess the safety and effectiveness of different anaesthetic providers for patients undergoing surgical procedures under general, regional or epidural anaesthetic. A subsidiary question is to determine whether there are types of procedures or patient groups for which a non-physician anaesthetist is not appropriate. We will consider results from studies within different regions (US, UK, other developed countries and developing countries) initially and then assess whether results are consistent across regions before combining results.

Methods

Criteria for considering studies for this review

Types of studies

We will include randomized controlled trials (RCTs), quasi-randomized trials in which the allocation to the intervention was decided by non-random means (such as alternation, digits in date of birth or other identification (ID) number) and cluster randomized trials.

Previous reviews have found no RCTs on this topic. Reasons why RCTs are unlikely to be performed include logistic difficulties such as allocation concealment and blinding of participants and personnel. Even without any blinding in place, randomization may be unacceptable to health service providers or ethics approval committees, particularly for high-risk patients. This may prevent this important patient group being included in trials.

In the absence of RCTs, we will include non-randomized controlled trials (NRCTs) and non-randomized cluster trials. We will consider all designs of observational studies which have included a comparison group, including prospective and retrospective cohort study designs, controlled before-after study designs, prospective and retrospective case-control study designs and interrupted time-series. We will not include descriptive studies without a direct comparison group.

We will consider non-randomized studies (NRS) separately and will not include them in a meta-analysis.

Types of participants

We will include studies of patients of all ages undergoing emergency or elective surgery under general anaesthetic in a hospital setting. We will not include patients undergoing obstetric surgery.

Types of interventions

We will include studies which have compared an anaesthetic administered by an NPA working independently with any one of:

1. an anaesthetic administered by a physician anaesthetist working independently;

2. an anaesthetic administered by a physician anaesthetist working as part of an anaesthetic team (e.g. team to include NPA, nurse anaesthetists, anaesthesia technicians etc.);

3. an anaesthetic administered by an NPA working as part of an anaesthetic team (e.g. team to include physician anaesthetist, nurse anaesthetists, anaesthesia technicians etc.).

We will take into consideration the difference in terminology of anaesthetic personnel between countries, which can potentially lead to confusion (Vickers 2002). Throughout we will use the terms 'physician anaesthetist' and 'non-physician anaesthetist' (NPA), as defined above. Examples of different names for anaesthetic personnel are given in Appendix 1. Where a study author uses an unclear term to describe an anaesthetic provider that we are unable to designate to one of the above categories, we will contact the authors to seek clarification.

There are also various terms used to describe the role of the main anaesthetic practitioner within a team. Some NPAs may be described as working 'under supervision' or 'medically directed'. For the purpose of this review we will follow the Medicare Advantage Medical Policy (Medicare Policy 2005) to distinguish between directed or supervised team work as it is anticipated that the majority of eligible studies will be based on Medicare data. For the purpose of billing, physician anaesthetists are required to define their work as personally performed, medically directed (performed by an NPA whilst the physician anaesthetist oversees no more than four concurrent procedures) or medically supervised (performed by an NPA who is directed by a physician other than the physician anaesthetist). The physician anaesthetist in the latter case may be responsible for overseeing more than four concurrent procedures. The extent to which an NPA is working independently, that is without the medical direction of an anaesthetist, may be difficult to ascertain. We will ensure that we follow the above definitions as far as possible, contacting authors for clarification if necessary to avoid misclassification of the intervention and comparison in studies.

Types of outcome measures

Primary outcomes
  1. Mortality within 30 days of anaesthetic

  2. Failure to rescue between induction and full recovery ("defined as the rate of death after complications" (Silber 2000))

  3. Serious airway complications (such as brain damage, emergency airway, unplanned intensive care unit (ICU) admission) and respiration complications (such as infection, aspiration), all within 30 days of anaesthetic

Secondary outcomes
  1. Other anaesthetic complications (such as nausea and vomiting, pain, sore throat, dental damage) within 48 hours

  2. Length of hospital stay

  3. Cost

  4. Patient reported satisfaction

Search methods for identification of studies

Electronic searches

We will search for eligible trials in the following databases, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (via Ovid) (from 1985 to the present), EMBASE (via Ovid) (from 1985 to the present) and CINAHL (via EBSCO) (from 1985 to the present). We will also search trial registers such as www.clinicaltrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform (http://www.who.int/ictrp/network/en/) for on-going trials. We will search grey literature databases such as the Healthcare Management Information Consortium (HMIC) and the National Technical Information Service (NTIS).

A draft search strategies for MEDLINE is presented in Appendix 2. The search strategy does not include any outcomes and is not limited by study design or publication type. No language restrictions will be imposed. On retrieval of studies we will assess any free text terms or MeSH terms for NPAs that we have not used and include these in a modified search strategy. This modified search strategy will be reported in the review.

Searching other resources

We will include other relevant systematic reviews in the search and undertake forward and backward citation tracking for key articles. We will contact investigators known to be involved in previous studies to enquire about on-going or unpublished studies.

Data collection and analysis

Selection of studies

Results of the searches will be collated and duplicates removed. The selection of eligible articles will initially look for RCTs and then for eligible NRS. All titles and abstracts will be screened by Sharon Lewis (SL) and Amanda Nicholson (AN) to remove studies that are very unlikely to be eligible. A pilot of 100 titles will be performed before all titles are reviewed in order to clarify criteria for discarding articles at this stage. We will identify potentially eligible RCTs and NRS separately. If no abstract is available but the title is possibly relevant, the full text of the article will be obtained. We anticipate that we may need to get more full texts for observational studies as abstracts may not contain sufficient detail to allow classification (Higgins 2011 Section 13.3.1.3).

When all titles and abstracts have been screened, the full text of potentially relevant titles will be reviewed by SL and AN and data recorded on the study eligibility section of the data extraction form. We will have separate eligibility forms for RCTs and NRS (drafts are included in Appendix 3). The NRS eligibility form will use study design features rather than study design labels, based on the tools presented at the UK Contributors' Meeting 2012. These features fall into four groups; Was there a relevant comparison? How were the groups formed? Were the features of the study described below carried out after the study was designed? On what variables was comparability of groups assessed? These will be incorporated into the data extraction form (Appendix 3).

A pilot selection of 10 papers for both RCTs and NRS will be read and then the investigators will meet to compare results and modify the forms as required. SL and AN will then read all potentially relevant papers and meet to compare results. Differences that cannot be resolved by discussion will be referred to Andrew Smith (AF). Numbers of papers retrieved and exclusions at each stage, with reasons, will be recorded in a PRISMA flowchart. Details of ineligible papers which are well-known or might appear to be eligible will be summarized in the 'Characteristics of excluded studies' table.

Data extraction and management

Data will be extracted from eligible studies by SL and AN using a paper-based data extraction form (a draft proposal of this is included in Appendix 3). This form will be reviewed after data from the first three papers have been entered, and modified as required. If there are duplicate publications from the same study, we will create a composite dataset from all the eligible publications.

The following items will be included in the RCT data extraction form.

  • Methods: to include risk of bias assessments (see below).

  • Patient group: to include age, sex, relevant sociodemographics, case-mix.

  • Setting: e.g. rural or urban, country.

  • Intervention: to include training, experience and the level of supervision, role and responsibilities of NPA.

  • Comparison: to include training and experience of anaesthetist.

  • Outcome: to include time points, i. measured and ii. reported; unit of measurement.

  • Results: to include missing participants, subgroup analyses.

The following additional items will be included in the NRS data extraction form reflecting additional concerns about bias and study design.

  • Data source: routine or study-specific source, retrospective or prospective collection.

  • Confounders and how they were adjusted for.

  • Unit of analysis issues.

  • Results: both unadjusted and adjusted results.

If relevant information or data are not available in the paper, we will contact the lead author to request the additional details. Disagreements will be resolved by discussion and if necessary consultation with AS.

Assessment of risk of bias in included studies

Randomized controlled trials (RCTs)

We will use the Cochrane risk of bias tool (Higgins 2011) assessing the following.

i. Selection bias:        

  • sequence generation;

  • allocation concealment.

ii. Performance bias:  

  • blinding of participants and personnel;

  • blinding of outcome assessors.

iii. Attrition bias:           

  • incomplete outcome data;           

  • blinding of participants;

  • personnel and outcome assessors.

iv. Detection bias:       

  • blinding of participants, personnel and outcome assessors;

  • other potential threats to validity.

v. Reporting bias:        

  • selective outcome reporting.

Blinding of all personnel is clearly not feasible for this research question and blinding of participants may be difficult. It will be important to assess the comparability of intervention and comparison groups at baseline, examining the types of operation undertaken and co-morbidities and risk status of patients to exclude any selection bias.

We will record assessments as high risk, low risk or unclear and a risk of bias table will be completed for each eligible RCT. For each outcome, summary risk of bias assessments within domains will be presented in risk of bias graphs or figures and across domains in the 'Summary of findings' table.

1. Selection bias

Non-randomized studies (NRS)

We anticipate that we will encounter a range of NRS designs. We will use the specific NRS risk of bias tool presented at the UK Contributors' Meeting 2012 (incorporated into the data extraction form for NRS (Appendix 3)).

The direction and impact of bias across different NRS is dependent on individual study features and hence is hugely variable and difficult to predict (Deeks 2003). In this review, selection bias and confounding by indication are of particular concern. Many NRS in this review are likely to use routine hospital data with retrospective data collection using billing or administrative codes as a basis for deciding the intervention group or outcomes. This raises particular issues in relation to accuracy of data and the effect of large samples on the weighting of effect estimates. 

Important confounding factors for this research question are:

  • case-mix and type of surgical procedure;

  • patient age; 

  • patient co-morbidity;

  • hospital characteristics.

 Using the data extraction form (Appendix 3) for each NRS we will:

  • identify the relevant confounders described by the researcher;

  • identify the method for identifying relevant confounders as described by the researchers;

  • identify the method used for controlling for confounding at both the design stage and analysis stage;

  • score all confounders, including those not specified by the researchers, for the precision with which the confounder is measured, imbalance between groups, the care with which the adjustment for the confounder was carried out.

2. Performance bias

We will record the methods and data used to decide which patients belonged to the intervention or comparison groups, with an estimate of their reliability. Information to be used includes billing code for an individual procedure, when it can be difficult to be confident about whether, for example, a physician anaesthetist was actually administering the anaesthetic (Silber 2000). In other studies, the intervention or comparison group has been assigned based on a questionnaire to hospital administrators about usual anaesthetic personnel at the hospital (Simonson 2007). There are sometimes unit of analysis issues to consider here if the intervention group has been assigned at the level of a hospital but individual patient outcomes are analysed.

3. Detection bias

For studies using routine hospital data, there may be errors or omissions in recording outcomes, depending on coding practice within the hospital. Failure to rescue rates, which rely on the recording of a complication before death, have been shown to be very sensitive to the completeness of coding of these secondary diagnoses (McKee 1999). If the intervention and comparison groups are in different hospitals with different coding practices this may have a considerable influence on results.

Measures of treatment effect

RCTs

For dichotomous outcomes, such as mortality, we will enter the total number of participants and number of events into RevMan (RevMan 5.1) to calculate risk ratios with 95% confidence intervals. For continuous data, such as length of hospital stay, we will calculate weighted mean differences. If data are presented in other forms and we are unable to source the original figures from the study authors, we may use the generic inverse variance option in RevMan. It is likely that patient reported satisfaction will be measured on different scales for each study. In this case we will use the standardized mean and mean differences when combining results. Cost of different anaesthetic providers will be standardized to GBP in 2010 using the Cochrane CCEMG EPPI-Centre Cost Converter (v.1.2) and the standardized values used in the review (http://eppi.ioe.ac.uk/costconverstion/default.aspx).

NRS

On the data extraction form we will record all unadjusted and adjusted effect estimates for all eligible outcomes, with details of confounders included for each estimate. Odds ratios are likely to be the most common effect measure used for dichotomous outcomes. Regression coefficients or analysis of covariance will be recorded for continuous variables. 

In an attempt to control for confounding, we will use adjusted rather than unadjusted effect estimates from NRS in the analysis and discussion of study findings. If multiple adjusted estimates are given we will use the estimate that includes the largest number of our pre-determined key confounders.

Unit of analysis issues

RCTs

Cluster randomized trials may be included in the review, where hospitals or surgical units have been randomized. Some studies may have further levels of clustering, for example surgical units within hospitals. We will extract data from these studies directly only if the analysis properly accounts for the cluster design using methods such as multi-level modelling or generalised estimating equations. If these adjustments are not made within the report we will undertake additional analyses by recalculating standard errors based on the design effect (Higgins 2011 Section 16.3.6). The resulting effect estimates and their standard errors will be analysed using generic inverse variance methods in RevMan.

NRS

The intervention or comparison group may be decided or assigned at a hospital level and this needs to be accounted for in any analysis, since these hospitals may differ in many respects other than anaesthetic provider. Incorrect analysis will result in residual confounding in the model. The use of multi-level or hierarchical models will be recorded and if the appropriate analysis is not reported we will contact the authors.

Dealing with missing data

We will contact study authors to request missing outcome data or any other methodological details. Missing outcome data are likely to be more of an issue in RCTs or prospective cohort studies, where data are collected specifically for the study. We will undertake sensitivity analyses to assess the impact of the missing outcomes using, for example, worst case scenario, last observation carried forward and available case analysis.

Assessment of heterogeneity

RCTs

We expect there will be considerable heterogeneity with any RCTs due to differences in:

  • countries (US, UK, other developed world, developing world);

  • training and supervision of NPA;

  • patient group including age and co-morbidity;

  • type of surgery undertaken.

As discussed in the 'Background' section, differences between countries are likely to be the most important source of heterogeneity. If we find sufficient studies we will combine studies for each outcome within a region initially. Some variables, such as NPA salary and training, will only be investigated within a region as comparisons, of for example the salary of an NPA in US and Africa, may be misleading. We will only combine studies across different regions in one meta-analysis if study design and type of intervention or comparison are equivalent. We will examine this heterogeneity visually using forest plots, initially across all studies and then grouped by the factors which might explain the variation. Heterogeneity will be assessed using the Chi2 and I2 statistics and explored using subgroup analyses and meta-regression. The presence of an I2 value of more than 80% would argue against presenting a pooled value.

NRS  

(Higgins 2011 Sections 13.6.2.3 and 13.6.2.4)

We expect to find more heterogeneity between NRS than between RCTs, reflecting differences in study design and scope for bias as well as intrinsic differences in the intervention. It has been estimated that heterogeneity leads to uncertainty 5 to 10 times that of a 95% confidence interval (Deeks 2003). We will again use a forest plot to display the most adjusted estimates from each study and use Chi2 and I2 statistics to describe heterogeneity. If possible, we will explore additional heterogeneity due to design and analysis features using subgroup analyses and meta-regression. Study characteristics that may be important include:

  • number of confounders included in models;

  • analysis technique used;

  • type of data collection.

Assessment of reporting biases

RCTs

We will aim to minimise reporting bias by identifying trials in progress or that are unreported from trial registers and contacting authors. If sufficient studies are included in the review we will review funnel plots to detect any publication bias and test for this statistically using Egger’s test.

Reporting bias may also occur within studies, with certain outcomes not reported. By referring to the protocol, where available, we will identify outcomes which have been collected but not reported and contact authors to request data.

NRS

Reporting bias and missing studies are a more complex issue for NRS than for RCTs. Registration and publication of protocols for observational studies is not as widespread as for RCTs so it is not easy to identify the finite population of studies to be included. For this research question there is in fact an existential question concerning the definition of an eligible study. Since routine hospital databases are used in many studies, it could be argued that the pool of eligible studies includes all hospitals which utilize a range of anaesthetic providers and have electronic longitudinal health databases. It clearly will not be possible to access all these databases. It is not clear whether the size of a study or direction of effect are likely to be associated with likelihood of publication, given that many hospital studies are very large but of uncertain quality. These uncertainties undermine the use of a funnel plot.  

We will aim to include a wide range of studies using a wide search and to not exclude potentially eligible articles without reference to the full text.  

Data synthesis

RCTs

We will attempt meta-analysis if we have two or more studies reporting comparable effect measures for a given outcome, and measures of heterogeneity are not excessive. An I2 value of more than 80% would argue against presenting a pooled value. The choice of statistical model will depend on the studies that are included but we may need to use the inverse variance method for some outcomes.

NRS

(Higgins 2011Sections 13.6.2.3 and 13.6.2.4)

We do not intend to present pooled estimates of effects from NRS studies.

If we have comparable effect estimates we will display the most adjusted results from each study in a forest plot but without a pooled estimate. We will sort studies in the forest plot by design features, as described in the heterogeneity section. The results from studies may be too disparate to display together in a forest plot and then we will use narrative synthesis to summarize direction, size and consistency of effects across studies. We will modify the 'Characteristics of included studies' table to present the relevant information in each report and to ensure that equivalent data are presented on all studies. Subgroups, as discussed above, will be used and the studies grouped accordingly. The results within and between groups will be summarized and discussed.

Subgroup analysis and investigation of heterogeneity

We will analyse the subgroups described below for RCTs:

  • countries, US, UK, other developed countries and developing countries;

  • training and supervision of NPAs;

  • patient group including age and co-morbidity;

  • type of surgery undertaken.

We will use differences in effect sizes, assessed by I2 statistics, between patient groups or types of procedures to address our subsidiary research question of whether NPAs might not be appropriate anaesthetic providers for certain patient groups.

Sensitivity analysis

Subgroup analyses based on risk of bias, design features and analysis techniques will form important sensitivity analyses to assess the impact of bias in both RCTs and NRS.

We will also undertake sensitivity analyses to assess whether unvalidated scales for patient reported outcomes such as pain or satisfaction affect the results.

For NRS, we will analyse:

  • number of confounders included in models;

  • analysis technique used;

  • type of data collection.

Summary of findings

We will use the principles of the GRADE system (Guyatt 2008) to assess the quality of the body of evidence associated with outcomes of mortality, serious airway complications, respiratory complications, length of hospital stay, cost and patient reported satisfaction. We will construct a 'Summary of findings' (SoF) table using the GRADE software. The Grade approach appraises the quality of evidence for an outcome and assesses how confident we can be that our estimate of effect or association reflects the real association. The quality measures considered include design (randomized trial, observational study or other), risk of bias (methodology quality), the directness of the evidence, heterogeneity of the data, precision of effect estimates and risk of publication bias. Summary of findings tables will be completed by SL and AN. Disagreements will be resolved by discussion and if necessary consultation with AS.

Acknowledgements

We would like to thank Anna Lee (content editor); Nathan Pace (statistical editor); Vera Meeusen, Clarence J Biddle, Aidan O'Donnell and Jamie Sleigh (peer reviewers) for their help and editorial advice during the preparation of this protocol for the systematic review.

We would like to thank Professor Barnaby Reeves for his advice and training on the use of NRS at the UK Contributors' Meeting 2012.

Appendices

Appendix 1. Types of anaesthetic personnel

Medically qualified: physician anaesthetist

Anaesthetist

 

Anesthesiologist

Sometimes called anesthetist.

 

Term used in, although not unique to, US. Also called anaesthesiologist.

 

Non-physician anaesthetist

CRNA

 

 

 

Anaesthesia technicians

 

Nurse anaesthetists

 

Circulation nurses

 

PA(A)

 

 

Clinical officers

 

Theatre practitioner (with extended role)

 

Anesthesiology assistants

 

Certified Registered Nurse Anesthetist. Specific to US. Specially trained to administer all anaesthetics. In most US states will work under supervision. CRNAs are allowed to work unsupervised in 16 states. Can be referred to as anesthetists in US literature.

 

Responsible for preparing operating theatre, checking machinery etc.

 

Involved in some anaesthetic procedures. Provide supervised assistance within a team.

 

Involved in preparation of anaesthetic drugs. Provide supervised assistance within a team.

 

Physician assistants (anaesthesia). Previously called anaesthetic physician assistants (APA). Involved in induction of anaesthetics to ASA 1 & 11 patients. Supervised.

 

Work in developing world. Responsibilities vary.

 

May have training to assist specifically within anaesthetic team.

 

 

Provide supervised assistance to anesthesiologist.

 

 

Appendix 2. OVID MEDLINE search strategy

1. exp *Anesthesia/ or exp *Anesthesiology/ or an?esth*.ti,ab.
2. (CRNA or certified registered nurse anaesth* or anaesthetic officer).mp. or exp Nurse Anesthetists/ or ((nurs* or assistant* or technician*) adj3 an?esth*).mp. or (physician adj3 ((extender or assistant*) adj5 (anaes* or anesth*))).mp. or ((mid-level adj3 provider) or advanced registered nurse practitioner or clinical officer).mp. or (physician adj3 (extender or assistant*)).mp. or operating department practitioner.mp. or exp Physician Assistants/ or exp Patient Care Team/ or exp Operating Room Technicians/ or exp Health Personnel/ or exp Health Manpower/ or Nursing/
3. 1 and 2
 

Appendix 3. Data extraction form - RCTs

Data Collection Form - RCTs

 

Review title or ID

 

 

 

Study ID (surname of first author and year first full report of study published e.g. Smith 2001)
 

 

Report IDs of other reports of this study (e.g. duplicate publications, follow-up studies)

 

 

 

Notes:

 

 

 

 1.  General Information

Date form completed (dd/mm/yyyy) 
Name/ID of person extracting data 

Report title

(title of paper/ abstract/ report that data extracted from)

 

Report ID

(ID for this paper/ abstract/ report)

                                                                       

Reference details

 

 

 
Report author contact details 

Publication type

(e.g. full report, abstract, letter)

 
Study funding sources (including role of funders) 
Possible conflicts of interest (for study authors) 
Notes:

 

 

2.  Study Eligibility

Study Characteristics

Eligibility criteria

 

 

Yes            No        Unclear

Location in text

(pg & ¶ /fig / table)

Type of study

Randomized Controlled Trials

 

  
Participants

General, spinal or epidural anaesthetic.

 

Hospital setting

 

  
Types of interventionAnaesthetic given by NPA working independently.  
Types of comparisons

Anaesthetic given by anaesthetist working independently.

 

Anaesthetic given by anaesthetist working as part of a team.

 

Anaesthetic given by NPA working as part of a team.

 

 

 

 

Types of outcome measures

Mortality from GA within 30 days.

 

Complications from GA.

 

Patient reported satisfaction

  

 

  

                                  INCLUDE                  EXCLUDE 

 

Reason for exclusion 

Notes:

 

 

 

DO NOT PROCEED IF EXCLUDED FROM REVIEW

 

 3.  Population and setting

 

Description

(include comparative information for each group (i.e. intervention and controls) if available

Location in text

(pg & ¶ /fig / table)

Population and description

(from which study participants are drawn)

  

Setting

(including country, rural/urban and social context)

  

Inclusion criteria

 

 

  

Exclusion criteria

 

 

  
Method/s of recruitment of participants  

Informed consent obtained

 

Yes        No    Unclear   

Notes:

 

 

 

 

 4.  Methods

 Descriptions as stated in report/paper

Location in text

(pg & ¶ /fig / table

Aim of study

 

 

  

Design (e.g. parallel, crossover, cluster)

 

  

Unit of allocation

(by individuals, cluster /groups or body parts)

  

Start date

 

 

  

End date

 

 

  

Total study duration

 

  
Ethical approval needed/obtained for studyYes        No    Unclear     

Notes:

 

 

 

 

 

5.  Risk of Bias assessment

Domain

Risk of bias

 

 

High  Low Unclear

Support for judgement

Location in text

(pg & ¶ /fig / table

Random sequence generation

(selection bias)

   

Allocation concealment

(selection bias)

   

Blinding of participants and personnel

(performance bias)

 Primary outcomes:  mortality 
  

Primary outcome: complications from GA

 

 

 

 

 
  

Patient reported satisfaction

 

 

 

 

Blinding of outcome assessment

(detection bias)

 

Primary outcome: mortality

 

 

 
  

Primary outcome: complication from GA

 

 

 

 
  

Patient reported satisfaction

 

 

 

 

Incomplete outcome data

(attrition bias)

 Mortality 
  

Complications from GA

 

 

 
  

Patient reported satisfaction

 

 

 

Selective outcome reporting

(reporting bias)

   

Other bias

 

   

Notes:

 

 

 

 

 

 6.  Participants

Provide overall data and, if available, comparative data for each intervention or comparison group.

 Description as stated in report/paperLocation in text  (pg & ¶ /fig / table

Total no. randomized

 

  

Clusters

(if applicable, no., type, no. people per cluster)

  

Baseline imbalances

 

  

Withdrawals and exclusions

(if not provided below by outcome)

  

Age

 

  

Sex

 

  

Race/Ethnicity

 

  

Severity of illness

(e.g. ASA I or II)

  

Co-morbidities

 

  

Other treatment received

 

 

  

Other relevant sociodemographics

 

  

Subgroups measured

 

 

  

Subgroups reported

 

 

  

Notes:

 

 

 

 

 

7.1  Intervention group  (repeat as necessary)

 

Description as stated in report/paper

 

Location in text

(pg & ¶ /fig / table

Intervention

(e.g. anaesthetic given by NPA working independently)

 

 

 

Type of anaesthetic

(general, spinal, epidural or mix)

 

  

Type of surgical procedure and method

 

 

  

No. randomized to group

(specify whether no. people or clusters)

  

Experience & training of NPA

 

  
Role & specific responsibilities of NPA  

Duration of treatment period

 

  

Other providers in theatre

(e.g. surgeon, nurse practitioners)

  

Co-interventions

 

 

 

  

Notes:

 

 

 

 

 

 8.1  Outcomes (repeat as necessary)

 Description as stated in report/paper

Location in text

(pg & ¶ /fig / table

Outcome name

 

  

Time points measured

 

 

 

  

Time points reported

 

 

 

  

Outcome definition

(with diagnostic criteria if relevant)

 

  

Person measuring/reporting

 

 

  

Unit of measurement

 

  

Scales: upper and lower limits

(indicate whether high or low score is good)

  

Is outcome tool validated?

 

Yes        No    Unclear   

Imputation of missing data

(e.g. assumptions made for ITT analysis)

  

Assumed risk estimate

(e.g. baseline or population risk noted in Background)

 

  

Power

 

  

Notes:

 

 

 

 

 

 

 9.1 Results – dichotomous results (repeat as necessary)

 

Description as stated in report/paper

 

Location in text

(pg & ¶ /fig / table

Comparison

 

  

Outcome

 

  

Subgroup

 

  

Timepoint

(specify whether from start or end of intervention)

  

Results

 

 

 

InterventionComparison 
No. eventsNo. participantsNo. eventsNo. participants
    
No. missing participants and reasons  
No. participants moved from other group and reasons  

Any other results reported

 

  

Unit of analysis

(by individuals, cluster/ groups or body parts)

  
Statistical methods used & appropriateness of these methods (e.g. adjustment for correlation)  

Reanalysis required?

(specify)

 

Yes        No    Unclear   

Reanalysis possible?

 

 

Yes        No    Unclear   
Reanalysed results

 

 

 

 

 

Notes:

 

 

 

 

9.2. Results – continuous data (repeat as necessary)

 

Description as stated in report/paper

 

Location in text

(pg & ¶ /fig / table

Comparison

 

  

Outcome

 

  

Subgroup

 

  

Timepoint

(specify whether from start or end of intervention)

  

Post-intervention or change from baseline?

 

  

Results

 

 

 

InterventionComparison 
MeanSD (or other variance)No. participantsMeanSD (or other variance)No. participants
      
No. missing participants and reasons  
No. participants moved from other group and reasons  

Any other results reported

 

  

Unit of analysis

(by individuals, cluster/ groups or body parts)

  
Statistical methods used & appropriateness of these methods (e.g. adjustment for correlation)  

Reanalysis required?

(specify)

 

Yes        No    Unclear   

Reanalysis possible?

 

 

Yes        No    Unclear   
Reanalysed results

 

 

 

 

 

Notes:

 

 

10.  Applicability                                                                                                    

Have important population groups been excluded from the study? (consider disadvantaged populations, and possible differences in the intervention effect)Yes    No    Unclear  

Is the intervention likely to be aimed at disadvantaged groups?

(e.g. lower socioeconomic groups)

 

Yes    No    Unclear  

Does the study directly address the review question?

(any issues of partial or indirect applicability)

Yes    No    Unclear  

Notes:

 

 

 

 

 

 

11.  Other information

 

Description as stated in report/paper

 

Location in text

(pg & ¶ /fig / table

Key conclusion of study authors

 

 

 

  

References to other relevant studies

 

 

  

Correspondence required for further study information

(from whom, what and when)

 

 

  

Notes:

 

 

 

 

END

Data Collection Form - NRS

 

Review title or ID

 

 

 

Study ID (surname of first author and year first full report of study published e.g. Smith 2001)

 

 

 

Report IDs of other reports of this study (e.g. duplicate publications, follow-up studies)

 

 

 

Notes:

 

 

 

 

1.  General Information

Date form completed (dd/mm/yyyy) 
Name/ID of person extracting data 

Report title

(title of paper/ abstract/ report that data extracted from)

 

Report ID

(ID for this paper/ abstract/ report)

                                                                       

Reference details

 

 

 
Report author contact details 

Publication type

(e.g. full report, abstract, letter)

 
Study funding sources (including role of funders) 
Possible conflicts of interest (for study authors) 
Notes:

 

 

 

 

2.1  Study Eligibility

Study Characteristics

Eligibility criteria

 

 

Yes            No        Unclear

Location in text

(pg & ¶ /fig / table)

Participants

General, spinal or epidural anaesthetic.

 

Hospital setting

 

  
Types of interventionAnaesthetic given by NPA working independently.  
Types of comparisons

Anaesthetic given by anaesthetist working independently.

 

Anaesthetic given by anaesthetist working as part of a team.

 

Anaesthetic given by NPA working as part of a team.

 

 

 

 

Types of outcome measures

Mortality from GA within 30 days.

 

Complications from GA.

 

Patient reported satisfaction

 

 

 

  

 

2.2 Study design features – individual.   (Additional explanatory notes available on request from authors)

List of study design features (for studies formed by classifying participants according to whether they received the intervention or comparator): individual-level group formation

 YesNoCan’t tellN/a
Was there a relevant comparison:    
     Between two or more groups of participants receiving different interventions?    
     Within the same group of participants over time?    
    
Were groups formed by:   
     Randomization?    
     Quasi-randomization?    
     Other action of researchers?    
     Time differences?    
     Location differences?    
     Health care decision makers?    
     Participants’ preferences?    
     On the basis of outcome?    

     Some other process (specify)?

 

    
     
Were the features of the study described below carried out after the study was designed?   
     Identification of participants    
     Assessment before intervention    
     Actions/choices leading to an individual becoming a member of a group    
     Assessment of outcomes    
    
On what variables was comparability of groups assessed?   
     Potential confounders    
     Assessment of outcomes before intervention    
      

 

Ideally, review authors should record the basis for their judgements (e.g. by quotations from the text of a paper), as they do when assessing the risk of bias.

2.3 Study design features – cluster (Additional explanatory notes available on request from authors)

  List of study design features (studies formed by classifying clusters by intervention and comparator): individual-level group formation

 

 YesNoCan’t tellN/a
Was there a relevant comparison:    
     Between two or more groups of clusters receiving different interventions?    
     Within the same group of clusters over time?    
    
Were groups formed by:   
     Randomization?    
     Quasi-randomization?    
     Other action of researchers?    
     Time differences?    
     Location differences?    
     Public health / policy decision?    
     Cluster preferences?    

     Some other process (specify)?

 

 

    
     
Which parts of the study were carried out after the study was designed?   
     Identification of participating clusters    
     Assessment of baseline?    
     Assessment of allocation to interventions    
     Assessment of outcomes    
    
On what variables was comparability assessed?   
     Potential confounders    
     Baseline assessment of outcome variables    

 

Note that ‘cluster’ refers to an entity (e.g. an organisation), not necessarily to a group of participants; ‘group’ in a cluster-allocated study refers to one or more clusters.

Ideally, review authors should record the basis for their judgements (e.g. by quotations from the text of a paper), as they do when assessing the risk of bias.

 

2.4 Eligibility decision

  INCLUDE                 EXCLUDE
Reason for exclusion 

Notes:

 

 

 

 

 

 

DO NOT PROCEED IF EXCLUDED FROM REVIEW

 

 3.  Population and setting

 

Description

(include comparative information for each group (i.e. intervention and controls) if available

Potential source of bias?

(tick then add to section 8)

 

Location in text

(pg & ¶ /fig / table)

Population and description

(from which study participants are drawn)

   

Setting

(including location and social context)

   

Inclusion criteria

 

 

   

Exclusion criteria

 

 

   
Method/s of recruitment of participants   

Informed consent obtained

 

Yes        No    Unclear   

Notes:

 

 

 

 

 4.  Methods

 Descriptions as stated in report/paper

Potential source of bias?

(tick then add to section 8)

Location in text

(pg & ¶ /fig / table

Aim of study

 

 

   

Design (e.g. parallel, crossover, cluster)

 

   

Unit of allocation

(by individuals, cluster /groups or body parts)

   

Start date

 

 

   

End date

 

 

   

Total study duration

 

   

Ethical approval needed/obtained for study

 

Yes        No    Unclear     

Notes:

 

 

 

 

5.  Participants

Provide overall data and, if available, comparative data for each intervention or comparison group.

 

Description as stated in report/paper

 

Potential source of bias?

(tick then add to section 8)

Location in text  (pg & ¶ /fig / table

Total no. participants

 

   

Clusters

(if applicable, no., type, no. people per cluster)

   

Withdrawals and exclusions

(if not provided below by outcome)

   

Age

 

   

Sex

 

   

Race/Ethnicity

 

   

Severity of illness

(e.g. ASA I or II)

   

Co-morbidities

 

   

Other treatment received

 

 

   

Other relevant sociodemographics

 

   

Subgroups measured

 

 

 

   

Subgroups reported

 

 

   

Notes:

 

 

 

 

6.1  Intervention group

 

Description as stated in report/paper

 

Location in text

(pg & ¶ /fig / table

Intervention

(e.g.Anaesthetic given by NPA working independently)

 

 

 

 

Type of anaesthetic

(general, spinal, epidural)

  

Type of surgical procedure and method

 

  

No. in group

(specify whether no. people or clusters)

  
Data source used to assign participants to group  

Training and experience of NPA

 

  

Duration of treatment period

 

  

Other providers in theatre

(e.g. surgeon, nurse practitioners)

  

Co-interventions

 

 

 

  

Notes:

 

 

 

 

 

7.1  Outcomes (repeat as necessary)

 Description as stated in report/paper

Location in text

(pg & ¶ /fig / table

Outcome name

 

 

 

 

 

Time points measured

 

 

 

  

Time points reported

 

 

  

Outcome definition

(with diagnostic criteria if relevant)

 

  

Data source used for outcome ascertainment

 

  

Unit of measurement

 

  

Scales: upper and lower limits

(indicate whether high or low score is good)

  

Is outcome tool validated?

 

Yes        No    Unclear   

Imputation of missing data

(e.g. assumptions made for ITT analysis)

  

Assumed risk estimate

(e.g. baseline or population risk noted in Background)

 

  

Power

 

 

  

Notes:

 

 

 

 

 

8.1  Confounding

 

Assessment of how researchers dealt with confounding

 

 

 

Method for identifying relevant confounders described by researchers:                                  Yes                                            

                                                                                                                                                 No

                                                                                                                                                     

If yes, describe the method used:

 

 

 

 

Relevant confounders described:                                                                                             Yes                                                                                   No                                                                                                                                                          

List confounders described below

 

 

 Method used for controlling for confounding

           At design stage:      matching by characteristics of subjects (see below for matching by                                                                                                 propensity score)

                                          Variables on which subjects matched: ………………………………….

                                                                                                       ………………………………….                             

                                                                                                       ………………………………….

                                                                                                       ………………………………….

At analysis stage:               stratification

                                           multivariable regression

                                           propensity scores (matching)

                                           propensity scores (multivariable regression)

 

Describe confounders controlled for below

 

 

Confounders described by researchers

Enter / preprint prespecified list of confounders (rank order in importance? Important in bold?)

Tick (yes/no judgement) if confounder considered by the researchers [Cons’d?]

Score (1 to 5) precision with which confounder measured

Score (1 to 5) imbalance between groups

Score (1 to 5) care with which adjustment for confounder was carried out.

 

Confounder

 

ConsideredPrecisionImbalanceAdjustment
Case-mixY/N/5/5/5
Co-morbidityY/N/5/5/5
Type of surgical procedureY/N/5/5/5
Type of anaestheticY/N/5/5/5
Hospital characteristicsY/N/5/5/5
 Y/N/5/5/5
 Y/N/5/5/5

9.1 Results – dichotomous outcomes (repeat as necessary)

 

Description as stated in report/paper

 

Location in text

(pg & ¶ /fig / table

Comparison

 

  

Outcome

 

  

Subgroup

 

  

Timepoint

(specify whether from start or end of intervention)

  
No. missing participants and reasons  
No. participants moved from other group and reasons  

Unadjusted results

 

 

 

InterventionComparison 
No. eventsNo. participantsNo. eventsNo. participants
    
Unadjusted summary results  

Adjusted results reported - 1

 

InterventionComparison 
No. eventsNo. participantsNo. eventsNo. participants
    
Adjusted summary results  
Confounders adjusted for  

Adjusted results reported - 2

 

InterventionComparison 
No. eventsNo. participantsNo. eventsNo. participants
    
Adjusted summary results  
Confounders adjusted for  

Reanalysis required?

(specify)

 

Yes        No    Unclear   

Reanalysis possible?

 

 

Yes        No    Unclear   
Reanalysed results

 

 

 

 

 

Notes:

 

 

 

 

9.2 Results – continuous outcomes

 

Description as stated in report/paper

 

Location in text

(pg & ¶ /fig / table

Comparison

 

  

Outcome

 

  

Subgroup

 

  

Timepoint

(specify whether from start or end of intervention)

  
No. missing participants and reasons  
No. participants moved from other group and reasons  

Unadjusted results

 

 

 

InterventionComparison 
MeanSD No.MeanSDNo.
      
Unadjusted summary results  

Adjusted results reported - 1

 

InterventionComparison 
MeanSD No.MeanSDNo.
      
Adjusted summary results  
Confounders adjusted for  

Adjusted results reported - 2

 

InterventionComparison 
MeanSD No.MeanSDNo.
      
Adjusted summary results  
Confounders adjusted for  

Reanalysis required?

(specify)

 

Yes        No    Unclear   

Reanalysis possible?

 

 

Yes        No    Unclear   
Reanalysed results

 

 

 

 

 

Notes:

 

 

 

 

10. Bias assessment  (additional explanatory notes available on request from authors)

Risk of bias table (non-randomized studies)

Item                                                             Judgementa             Description (quote from paper, or describe key information)

1.  Sequence generation

 

 

  

2.  Allocation concealment

 

 

  

3. Confoundingb    Mortality

 

 

  

                          Complication from GA

 

 

  

                            Patient satisfaction

 

 

  

4. Blinding?       Mortality

 

 

  

                            Complication from GA

 

 

  

                           Patient satisfaction

 

 

  

5.  Incomplete outcome data addressed?

                        Mortality

 

  

                           Complication from GA

 

 

  

                           Patient satisfaction

 

 

  

6.  Free of selective reporting?

                        Mortality

 

  

                           Complication from GA

 

 

  

                           Patient satisfaction

 

 

  

7.  Free of other bias?

 

 

  

8. A priori protocol?c

 

 

  

9. A priori analysis plan?d

 

 

  

 

 

a Some items on low/high risk/unclear scale (double-line border), some on 5 point scale/unclear (single line border), some on yes/no/unclear scale (dashed border). For all items, record “unclear” if inadequate reporting prevents a judgement being made.

b Based on list of confounders considered important at the outset and defined in the protocol for the review

c Did the researchers write a protocol defining the study population, intervention and comparator, primary and other outcomes, data collection methods, etc. in advance of starting the study? N.B. May be outcome specific.

d Did the researchers have an analysis plan defining the primary and other outcomes, statistical methods, subgroup analyses, etc. in advance of starting the study?

 

11.  Applicability                                                                                                    

Have important population groups been excluded from the study? (consider disadvantaged populations, and possible differences in the intervention effect)Yes    No    Unclear  

Is the intervention likely to be aimed at disadvantaged groups?

(e.g. lower socioeconomic groups)

 

Yes    No    Unclear  

Does the study directly address the review question?

(any issues of partial or indirect applicability)

Yes    No    Unclear  

Notes:

 

 

 

 

 

 

12.  Other information

 

Description as stated in report/paper

 

Location in text

(pg & ¶ /fig / table

Key conclusion of study authors

 

 

 

  

References to other relevant studies

 

 

  

Correspondence required for further study information

(from whom, what and when)

 

 

  

Notes:

 

 

 

 

 

Contributions of authors

Conceiving the review: Andrew F Smith (AF)

Co-ordinating the review: Sharon R Lewis (SL), Amanda Nicholson (AN)

Undertaking manual searches: SL and AN

Screening search results: SL and AN

Organizing retrieval of papers: SL

Screening retrieved papers against inclusion criteria: SL and AN

Appraising quality of papers: SL and AN

Abstracting data from papers: SL and AN

Writing to authors of papers for additional information: SL

Providing additional data about papers: SL and AN

Obtaining and screening data on unpublished studies: SL and AN 

Data management for the review: SL and AN

Entering data into Review Manager (RevMan 5.1): SL and AN

RevMan statistical data: AN and SL

Other statistical analysis not using RevMan: AN

Interpretation of data: AN, SL and AS

Statistical inferences: AN, AS, SL

Writing the review: SL and AN

Securing funding for the review: AS

Performing previous work that was the foundation of the present study: AS

Guarantor for the review (one author): AS

Person responsible for reading and checking review before submission: AN

Declarations of interest

From March to August 2011, AN worked for the Cardiff Research Consortium, which provides research and consultancy services to the pharmaceutical industry. The Cardiff Research Consortium has no connection with AN's work with The Cochrane Collaboration. AN's husband has small direct holdings in several drug and biotechnology companies as part of a wider balanced share portfolio.

AF was lead author on a previous non-Cochrane version of the review (Smith 2004). He was also funded by the UK Department of Health to run a project exploring the potential of employing non-medical anaesthetists in the UK healthcare setting (Kane 2005).

Sources of support

Internal sources

  • No sources of support supplied

External sources

  • National Institute for Health Research Cochrane Collaboration Programme Grant. Enhancing the safety, quality and productivity of perioperative care. Project Ref: 10/4001/04., UK.

    This grant funds the work of SL,AN & AS on this review

Ancillary