Do people with intellectual disabilities understand their prescription medication? A scoping review

Abstract Background People with intellectual disabilities are more likely to experience poor health than the general population and are frequently prescribed multiple medications. Therefore, it is important that people with intellectual disabilities understand their medication and potential adverse effects. Method A scoping review explored people with intellectual disabilities' knowledge of prescription medications, their risks and how medication understanding can be improved. Results Ten journal articles were included. People with intellectual disabilities often lacked understanding of their medication, including its name, purpose and when and how to take it. Participants were often confused or unaware of adverse effects associated with their medication. Information was sometimes explained to carers rather than people with intellectual disabilities. Some interventions and accessible information helped to improve knowledge in people with intellectual disabilities. Conclusion There is a need for accessible and tailored information about medication to be discussed with people with intellectual disabilities in order to meet legal and best practice standards.

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as epilepsy, diabetes and hypertension, compared to the general population. Compared to the general population with the relevant long-term condition, this included fewer people with intellectual disabilities and diabetes having a HbA1C record in the previous 15 months, and fewer people with asthma and intellectual disabilities having an asthma review in the previous 15 months.
An effective and optimized medication regime is an integral part of managing health conditions. It is important for patients to understand the information about their medication to facilitate the management of health conditions. As part of this, effectively informing patients about the risks of adverse effects is essential for them to make informed decisions about their medicine-taking and adhere to their treatment (Knapp, Raynor, & Berry, 2004). In the general population, prescription medication instructions and warnings are often complex and, as a consequence, may not be fully understood resulting in misuse and adverse effects (Davis, Wolf, Bass, Middlebrooks, et al., 2006;Davis, Wolf, Bass, Thompson, et al., 2006;Wolf, Davis, Shrank, Neuberger, & Parker, 2006;. In particular, studies have shown that people with low literacy levels often have difficulty both understanding and reading labels on medication (Davis, Wolf, Bass, Middlebrooks, et al., 2006;Wolf, Davis, Tilson, et al., 2006), which may predispose them to increased risk of experiencing adverse effects. The terms "adverse effects" and "side effects" of medicines are frequently used interchangeably. However, an "adverse effect" is an undesirable harmful effect resulting from a medicine, for example, ibuprofen increasing risk of peptic ulceration and olanzapine increasing the risk of constipation. Whereas a "side effect" is an effect secondary to the main or therapeutic effect of a medicine which may not necessarily be harmful and can be desirable in some circumstances. For the purposes of this scoping review, the present authors will refer to "adverse effects" with the exception of when reporting studies which have used different terminology.
There is often a high usage of prescription medications in people with intellectual disabilities. In a review of a general practice database, Straetmans, Schrojenstein Lantman-de Valk, Schellevis, and Dinant (2007) found that prescription medications were received by 75% of people with intellectual disabilities compared to 59% of people without intellectual disabilities, and people with intellectual disabilities received 5.4 repeat prescriptions per year compared to 1.6 by those without intellectual disabilities. More recently, research has focused on the high levels of prescriptions of psychotropic medication for people with intellectual disabilities. Doan et al. (2013) found 35% of adults living with intellectual disabilities were prescribed psychotropic medications, mainly antipsychotics. In particular, studies suggest people with intellectual disabilities may be inappropriately prescribed psychotropic medication for the management of behaviours that challenge (Deb & Unwin, 2007;Holden & Gitlesen, 2004;Matson & Neal, 2009;Sheehan et al., 2015;Singh & Matson, 2009). A UK population-based cohort study reported that 49% of 33,016 people with intellectual disabilities were prescribed psychotropic medication yet only 21% had a record of mental illness and 25% had a record of challenging behaviour (Sheehan et al., 2015). It has been estimated that, in England, up to 35,000 adults with intellectual disabilities are being prescribed a psychotropic medicine without appropriate clinical justification (NHS England, 2018).
People with intellectual disabilities may be at increased risk of poor medication knowledge as they often experience additional challenges in health-related communication due to factors including lack of accessible information, poor communication skills of healthcare professionals and communication, and adaptive and cognitive difficulties associated with intellectual disabilities (Marks, Sisirak, & Hsieh, 2008;Mastebroek, Naaldenberg, Lagro-Janssen, & van Schrojenstein Lantman de Valk, 2014). Indeed, Strydom, Forster, Wilkie, Edwards, and Hall (2001) found that over half of people with intellectual disabilities interviewed were unable to read the label on their antipsychotic medicine and 86% did not know, or only knew one of, the adverse effects of their medication.
Patient-centred practice is incorporated into guidelines for healthcare provision, including for people with intellectual disabilities. Patient-centred practice aims to focus care on the needs of the person receiving the care rather than the needs of the service (Royal College of Nursing, 2016). The General Medical Council (GMC) is a body that sets standards for doctors in the UK and GMC guidance (c) emphasizes the importance of the doctor-patient relationship where a dialogue is created between the parties together with an exchange of views to enhance the patient's decision-making process.
All organizations providing NHS care and/or publicly funded adult social care are legally required to follow the Accessible Information Standard (AIS;NHS England, 2016). This involves taking steps to ensure that the individual, including those with intellectual disabilities, receives information in an accessible format and receives any communication support they may need, and applies to discussions around medication (NHS England, 2017).

According to the Supreme Court case of Montgomery v
Lanarkshire Health Board (Scotland) (2015), where a person has capacity, healthcare professionals are under a duty "to take reasonable care to ensure that the patient is aware of any material risks involved in any recommended treatment, and of any reasonable alternative or variant" (para. 87). The judgement explains that a material risk is one that a "reasonable person in the patient's position" (para. 87) would consider significant or that the doctor is or should be aware that the patient would deem is significant (Barnett & Carr, 2018;Sokol, 2015). Where people with intellectual disabilities are concerned, the Montgomery case applies to those with mental capacity only, that is, able to make decisions for themselves about treatment. Therefore, the need to ensure that people with intellectual disabilities understand their medication, and its potential risks, is crucial in order to promote good health outcomes and to ensure that healthcare providers are complying with legal requirements.

| Aims
Prescribed medications to manage health problems have the potential to cause short-term and long-term adverse effects. An individual with intellectual disabilities, just as those without intellectual disabilities, should be enabled to take an active part in the decision-making process. Empowering people with intellectual disabilities to be equal stakeholders in relation to their medicines and encouraging dialogue about medicines could lead to an improvement in therapeutic relationships, better access to healthcare, improved adherence to pharmacological interventions and consequently a reduction in morbidity and mortality (Adams & Carr, 2017). There has been limited research exploring the understanding of medication within the intellectual disability population; therefore, this scoping review aimed to identify and analyse studies, which explored people with intellectual disabilities' understanding of prescription medications and the risks associated with these, along with how to improve understanding.

| Scoping review
Scoping reviews aim to map all of the relevant literature in a specific area of interest and consequently help to identify any gaps in existing research (Arksey & O'Malley, 2005). This approach was adopted as existing knowledge of the literature suggested a lack of previous research exploring people with intellectual disabilities' understanding of risks associated with their prescription medication. This review utilized Arksey and O'Malley's (2005) framework for scoping reviews which involves the following five stages: (1) identifying the research question; (2) identifying the relevant studies; (3) study selection; (4) charting the data; (5) collating, summarizing and reporting the results.

| Stage 3: Study selection
Studies were included if they (a) reported on people with intellectual disabilities' understanding of prescription medication from the perspective of people with intellectual disabilities or others (e.g., family members, paid caregivers) or (b) aimed to improve people with

| Stage 4: Charting the data
A data extraction sheet was developed in Excel, and relevant articles were charted using the following column headings:

| Included studies
The searches in 2017 and 2018 are presented together as the search methodology was the same. Initial searching of the aforementioned electronic databases provided 1,326 records. Four hundred and four duplicates were removed leaving 922 records to screen for relevance based on title and abstract. Based on title and abstract screening, 886 records were excluded. Thirty-six full-text articles were retrieved and assessed by the researchers for inclusion. Twenty-seven studies were excluded. A total of nine studies met all inclusion criteria and were subsequently included in the review. When screening the references of the nine included studies, one article (Dysch, Chung, & Fox, 2012) was found to fit the inclusion criteria and was therefore also included within the review. An overview of the study selection process is provided in Figure 1.

| Study characteristics
All identified articles reported completed studies. Characteristics of the included articles are summarized in Table 2 Australia (Davis et al., 2016(Davis et al., , 2014. All ten articles had been completed and published.

| Participants
All articles discussed adults (18+) with intellectual disabilities. Data were collected from participants with intellectual disabilities and asthma in two of the included studies (Davis et al., 2016(Davis et al., , 2014. Two studies involved participants with intellectual disabilities and diabetes (Dysch et al., 2012;Flood & Henman, 2015). One study interviewed females with intellectual disabilities who were using, intended to or had used contraception (Walmsley et al., 2016). The other five studies included in this scoping review were not constrained to a particular condition (Beacroft & Dodd, 2010;Ferguson & Murphy, 2014;Fish et al., 2017;Huneke et al., 2012;Sheehan et al., 2017). The studies were conducted in a range of settings including day services and supported living (Beacroft & Dodd, 2010;Huneke et al., 2012), secure psychiatry wards (Sheehan et al., 2017) and a self-advocacy conference (Fish et al., 2017).

| Knowledge of prescription medications
There was a range of findings about the medication knowledge of people with intellectual disabilities, but the majority of articles found evidence that many people with intellectual disabilities did not fully understand their prescription medication, including medication names, its purpose, when and how to take it and how to store it. with intellectual disabilities and asthma. They found that most participants were aware of their diagnosis and what their medication did for them, for example, "relax the airway when it's wheezy." Most participants were also able to link not taking medication to negative health consequences, for example, "if I don't take that, I feel a bit funny when I start walking. I get choked up a bit," "if I didn't use it I'd probably be in hospital" and "if I don't take this one, I get sick."

| Purpose of medication
Two studies found more variable medication knowledge, but with some notable cases of good understanding. In Dysch et al.'s (2012) study, one participant expressed an understanding of diabetes medication "so they have insulin injections to actually um, grasp more insulin inside themselves" and one participant was able to identify early warning signs that she had not taken her medication "I can tell when I've not had the tablets and stuff. Sometimes I feel hungry or empty.
And I've got to have something to make myself well." Some participants expressed understanding the consequences of not taking their medication "I know the consequences…where you might lose a limb did not know what medication they took and although 53% reported that they knew why they were taking prescription medications, they did not know the name of their medication(s). The majority of people with intellectual disabilities were happy to take medication for their pain when given to them by staff, but only 18% stated they would take medicine if they were in pain when alone at home, suggesting that independent use of medication was low.

| Decision making
Only two studies presented information about the decision to take medication. The case study participant in Flood and Henman (2015) stated that he took his tablets because he did not "want to die," suggesting that he understood the purpose of the medication and could use this to make a decision about whether to take it. Most participants in Walmsley et al. (2016) reported having the decision to use contraception made for them, with the exception of two women who appeared to be making proactive decisions about their contraception.

| Factors affecting medication knowledge
One study compared medication knowledge between patients with intellectual disabilities with and without capacity and found that medication knowledge was generally better for those patients with intellectual disabilities who had capacity (Huneke et al., 2012). Capacity was defined as having the capacity to consent

| Understanding of prescription medication risks
In comparison with general knowledge of prescription medication, the included articles presented little information regarding participants with intellectual disabilities' understanding of medication risks. Overall, participants were often confused or unaware of adverse effects associated with their prescription medication. Beacroft and Dodd (2010) found that the majority of participants (70%) said that they would take medication when in pain. However, when the remaining participants were asked why they would not take medication, they expressed confusion and concern about whether the pain medication would react negatively with their regular medication. It is not clear, however, whether the 70%, who said they would take their medication as a result of being in pain, had an understanding of the risks of taking their prescription medication, including potential reactions with other medication.

| Adverse effects
Three studies discussed participant's understanding of adverse effects of prescription medication, two of which found largely poor knowledge about disadvantages or adverse effects. All participants in Huneke et al.'s (2012) study demonstrated poor knowledge of the possible disadvantages of their medication. However, those with capacity showed very good knowledge on contraindicated foods and drinks. In Davis et al. (2016), the majority of participants seemed unaware of the adverse effects that could result from their asthma medication, although some participants were able to express some physiological undesirable effects of their inhaler, for example, "I had a bad reaction…my legs were shaking, my arms were shaking." The participant in Flood and Henman's (2015) case study appeared to have some knowledge of adverse effects. When discussing his medication with the researcher, he stated he knew that diarrhoea was a side effect of two of his medications. However, potential adverse effects of his other medications were not discussed so it cannot be concluded whether he had knowledge of the adverse effects of all his medication.

| Lack of information about risks
Two studies indicated that some people with intellectual disabilities recognized that they did not understand enough about the adverse effects and risks of their prescription medications, and expressed the desire for more information. Only one respondent

| How to improve knowledge of prescription medication in people with intellectual disabilities
Eight out of ten articles in this scoping review reported ways in which knowledge of prescription medication amongst people with intellectual disabilities could be improved. It was commonly suggested, that a wide array of sources of information should be readily available for people with intellectual disabilities including easy-read leaflets with pictures and/or diagrams and media platforms such as YouTube.

| Format of information
Four of the included studies discussed how medication information is presented to people with intellectual disabilities. Davis et al.'s qualitative study (2016) found that the way in which information was conveyed to people with intellectual disabilities using inhaled asthma medications was crucial. Written information was often reported to SMITH eT al.
be a challenge to understand, for example, one participant stated "it would be hard for me to read because I'm almost blind in one eye and I read things back to front." Some participants reported turning to media platforms, such as YouTube, to find out information regarding their medication (Davis et al., 2016).
Extending this, Fish et al. (2017) found that people would like information presented in ways other than verbally, that is, photos/ videos of how to use their medication (n = 3), mobile alerts/special alarm as a reminder/timetable (n = 4). They also expressed how aids such as hearing loops/braille/sign language and/or interpreters should be utilized when appropriate (n = 5).
Easy-read and pictorial support was specifically mentioned in two of the articles. pre-and post-test scores were similar, and there was no statistically significant difference, suggesting that the intervention was not effective at increasing medication knowledge.

| Training health professionals
As well as educating people with intellectual disabilities about their medication, five studies found that it is also important to train and educate health professionals in providing information to people with intellectual disabilities. It was identified that respiratory physicians, asthma educators, GPs and pharmacists are important in training inhaler use in people with intellectual disabilities (Davis et al., 2014).
Doctors' notes emphasized the need for staff knowledge and training "please make sure staff are aware of how to use the puffers with spacer," "buy spacer and teach him" to help people with intellectual disabilities understand how to use their medication. and Fish et al. (2017) (Beacroft & Dodd, 2010;Davis et al., 2016Davis et al., , 2014Fish et al., 2017;Huneke et al., 2012;Walmsley et al., 2016). Some studies suggested that people with intellectual disabilities are more likely to understand the purpose of their prescription medication than the potential disadvantages and adverse effects (Davis et al., 2016;Huneke et al., 2012). Some studies showed some people with intellectual disabilities were well informed about their medication (Ferguson & Murphy, 2014;Sheehan et al., 2017;Walmsley et al., 2016), and this could be related to better verbal abilities (Ferguson & Murphy, 2014 (Beacroft & Dodd, 2010) and lack of knowledge of adverse effects (Davis et al., 2016;Huneke et al., 2012).

| Accessibility and delivery of information
Guidelines for healthcare professionals outline the importance of patient involvement in the decision-making process and encourage effective communication directly with the patient (NICE, 2012), and the AIS (NHS England, 2016) specifies the responsibility of services to make information understandable and accessible to everyone.
Therefore, when involving people with intellectual disabilities in the decision-making process, it is essential to ensure the information being communicated is understandable and accessible (Adams & Carr, 2017). However, this review suggests that people with intellectual disabilities are not always receiving accessible information about their medication directly from healthcare professionals (Davis et al., 2016;Fish et al., 2017;Flood & Henman, 2015). Although people with intellectual disabilities often want their carers or family members to be informed about their medications and to be present during the consultation, they express frustration when the healthcare professional directs the information solely to the caregiver (Davis et al., 2016;Fish et al., 2017).
General recommendations for effective health promotion includes educating and empowering people with intellectual disabilities (Marks & Heller, 2003

| Education for people with intellectual disabilities
It is important to consider what can be done to ensure people with intellectual disabilities are supported to access and understand information regarding their medication, and risks of adverse effects. (2014)  In order to promote medication understanding, it is important to take into account the needs of the individual and to provide SMITH eT al.

Ferguson and Murphy
information in the most accessible way, which may include using pictures/diagrams, easy-read text, audio, video and braille (Fish et al., 2017;Simpson & Douglas, 2011;Strydom et al., 2001;The Disability Partnership, 2016). This places a particular emphasis on the availability, or creation, of appropriate resources. However, patient information leaflets supplied with dispensed medicines from pharmacies can be difficult to understand (Davis, Wolf, Bass, Middlebrooks, et al., 2006;Davis, Wolf, Bass, Thompson, et al., 2006). Easy-read medication leaflets are freely available on the Internet, but are of variable quality and often not updated for many years (Adams & Shah, 2016a, 2016b, meaning that healthcare professionals and/or carers may need to adapt more general resources about taking medications to meet the person with intellectual disabilities' needs (Hollins, Carpenter, Bradley, & Egerton, 2017;The Disability Partnership, 2016). Group education aimed at specific conditions may also be appropriate for some people with intellectual disabilities (Ferguson & Murphy, 2014), and in some areas, this could be embedded through workshops run by community learning disability teams.

| Strengths and limitations
One of the strengths of this scoping review was the use of the five-stage framework (Arksey & O'Malley, 2005), which allows for transparency and reproducibility. Another strength is the use of two researchers who independently identified and screened the data and the introduction of a third researcher who was consulted in the case of disagreements. Nine out of the ten studies included within this review collected data from the people with intellectual disabilities themselves. This is important as information from a secondary source such as a carer or support worker may not always accurately reflect the views of people with intellectual disabilities.
Several limitations to this scoping review should also be acknowledged. Firstly, articles were only included if published between 2011 and 2017. This approach was taken to focus on current practice, but it is acknowledged that studies prior to 2011 may also offer additional insights. In the majority of studies, the main aim was not to explore participants with intellectual disabilities' knowledge of medication; therefore, some of the findings reported here are only reflective of a relatively small aspect of the original paper. The majority of the studies were conducted in the UK, and so due to differing policy and practice contexts, these findings may not generalize to other countries. Also, some of the studies had limited sample sizes; for example, Dysch et al. (2012) included four participants and Sheehan et al. (2017) included six participants, and so applying findings to the rest of the population with intellectual disabilities could be problematic. Often the language used in the paper's analyses, for example, "some" of the sample, made it difficult to understand the number of participants whom expressed a particular view.

| CON CLUS IONS
Currently, research regarding the understanding of prescription medications in the intellectual disability population is sparse. This scoping review identified 10 studies addressing this issue. Although levels of knowledge about different aspects of medication use varied, often participants had poor knowledge of their medication, how to use it and what the risks of adverse effects were. The level of knowledge and information provision practices described here is unlikely to meet the guidelines currently in place. This review has indicated recommendations for promoting medication understanding based on empirical research, and future research should evaluate how best to improve medication understanding in people with intellectual disabilities.

ACK N OWLED G M ENTS
The authors would like to thank Marie-Anne Durand for her guidance and advice on scoping review methodology. The authors would also like to thank Rachael Mellor for her assistance during the screening process.

CO N FLI C T O F I NTE R E S T
The authors report no conflict of interests.

AUTH O R CO NTR I B UTI O N S
SM planned and drafted the study, protocol and data extraction