Adults with intellectual disabilities and mental health disorders in primary care: a scoping review

Background GPs are increasingly confronted with patients with both intellectual disabilities (ID) and mental health disorders (MHD). Currently, the care provided to these patients is found to be insufficient, putting them at risk of developing more severe MHD. Improving the quality of GP care will improve the whole of mental health care for this patient group. Therefore, an overview of the content and quality of care provided to them by the GP may be helpful. Aim To provide an up-to-date literature overview of the care provided by GPs to patients with ID and MHD, identify knowledge gaps, and inform research, practice, and policy about opportunities to improve care. Design and setting Scoping review. Method PubMed, PsycINFO, EMBASE, and grey literature were searched for publications concerning primary care and patients with ID and MHD. Selected publications were analysed qualitatively. Results One hundred publications met the inclusion criteria. Five overarching themes were identified: GP roles, knowledge and experience, caregiver roles, collaboration, and a standardised approach. The results show GPs’ vital, diverse, and demanding roles in caring for patients with both ID and MHD. GPs experience problems in fulfilling their roles, and gaps are identified regarding effective GP training programmes, applicable guidelines and tools, optimal collaborative mental health care, and corresponding payment models. Conclusion The improvement required in the current quality of GP care to patients with ID and MHD can be achieved by bridging the identified gaps and initiating close collaborations between care professionals, policymakers, and organisational managers.


INTRODUCTION
GPs are increasingly confronted with patients with both intellectual disabilities (IDs) and mental health disorders (MHDs), caused mainly by a growing need for care and support for people with mild to borderline intellectual disabilities (IQ , arising from an increasingly complex society. 1 Patients with ID have greater healthcare needs with higher levels of morbidity and premature mortality than patients without ID, 2,3 a situation where insufficient quality of health care is a substantial contributor. 2 Patients with coexisting MHD form an extra vulnerable group in this context. Although research shows that MHDs are 3-4 times more common in people with ID than in the general population, 4,5 primary and secondary care provided to these patients is insufficient. [6][7][8] This is the consequence of inadequate identification of IDs and MHDs, communication difficulties, atypical presentation of disorders, and a lack of assessment tools and treatment modalities specifically adapted to people with ID. [9][10][11] But the poor accessibility to (mental) health services for patients with ID is also described as an important contributing factor. 12,13 Consequently, patients with both ID and MHD are at risk of developing more severe or chronic MHDs, are prescribed more psychotropic medication, and use more services. 14 In many countries, GPs are often the first care providers contacted by these patients. Their care provision constitutes both a demand-driven approach in assessment, treatment, and follow-up of symptoms and disorders, and a more proactive approach aimed at prevention by identifying risk factors and providing health education. Adequate primary care, including both of these approaches, is essential for patients with both ID and MHD to prevent diagnostic delay and ensure appropriate and timely referral and early personalised treatment. 15 Although studies are increasingly published on expanding knowledge and skills within mental health care and ID care, 16,17 reported practices are mostly on a small scale and lack an orientation towards primary care. This is surprising and disturbing, considering GPs' important position in the mental healthcare system and the growing demands of this patient group.
A scoping review was conducted to enhance the level of knowledge and provide an up-to-date overview of GP care for patients with both ID and MHD, identify knowledge gaps, and inform research, practice, and policy about opportunities to improve care.

METHOD
This review follows Arksey and O'Malley's 18 framework for scoping reviews, revised by Khalil et al, 19 and describes methods and Abstract Background GPs are increasingly confronted with patients with both intellectual disabilities (ID) and mental health disorders (MHD). Currently, the care provided to these patients is found to be insufficient, putting them at risk of developing more severe MHD. Improving the quality of GP care will improve the whole of mental health care for this patient group. Therefore, an overview of the content and quality of care provided to them by the GP may be helpful. results in line with the PRISMA Extension for Scoping Reviews checklist. 20

Defining the research question
The guiding research question was: what has been described about the care for adult patients with both ID and MHD provided by GPs? The key concepts are defined in Supplementary Table S1.

Retrieving relevant publications
Relevant publications were identified using a three-step literature search. 19 First, PubMed, PsycINFO, and EMBASE were explored (date range from January 1994 to September 2019), using search terms pertaining to 'primary care' and 'intellectual disability', informed by an information specialist (Supplementary  Table S1). Selected publications were searched for keywords missed in the initial search. This yielded an additional search string for 'ID' (Supplementary Table S1). Second, relevant publications were retrieved from grey literature, using the recommendations from 'Grey Matters'. 21 Common search terms for 'primary care' and 'intellectual disability' in English and in Dutch were used (Supplementary Table S1). Third, the reference lists were searched for additional relevant publications.

Selection of publications
Duplicates were removed, and the first author performed a first selection on title and abstract. About 20% were double screened by a second independent researcher. The full texts were then screened by the first author and a second independent researcher. Any judgement differences were discussed to reach consensus within each review pair. When consensus could not be reached, a third reviewer became involved to resolve outstanding conflicts. Publications were included if they concerned adults with an ID, an MHD, and primary care following the prepared definitions. Other criteria were: • adult focused (≥18 years); • originating in Western European and Anglo-Saxon countries, where GPs have a comparable role as gatekeeper for more specialised mental health care; • available in full text; and • available in English or Dutch.
There was no selection on publication type. Publications on forensic primary care were excluded because they concern a selective group of patients beyond the scope of this review.

Presentation and collation of the data
A standardised data extraction form was developed to guide data charting for descriptive analysis, including publication year, country of origin, publication type, domain, and the care element(s) described. The selected publications' content was qualitatively analysed using conventional content analysis 22 supported by ATLAS.ti software (version 8.4). This process involved repeatedly reading the articles, identifying relevant text fragments, and inductively generating codes related to the research question. All coding was conducted by two researchers independently. Differences in coding were discussed to reach consensus. Codes were then sorted depending on how they were related. From this, major themes were developed and organised. This iterative process was followed critically by the research team, and key findings were discussed relating to the study's purpose and implications for future research, practice, and policy. Figure 1 presents the publication selection process. One hundred publications were included for final analysis (Supplementary Table S2). The publications' main domains were ID care (n = 39) and primary care (n = 34). The number of yield publications increases steadily over the years. In total, 46 of the publications described a scientific study, none of which were randomised controlled trials. Figure 2 presents the overview of relevant characteristics of included publications.

Prevalence of mental health disorders in primary care
The publications on register-based cohort studies report that people with ID have a

How this fits in
The GP, as first-line healthcare professional and gatekeeper, has a vital role in the mental health care of patients with both an intellectual disability (ID) and a mental health disorder (MHD). Current GP care is considered insufficient, and the quality of care needs to be improved. However, there is a need for an overview on the care provided to these patients by GPs. This scoping review provides an up-to-date literature overview of the care provided by GPs to patients with ID and MHD, identifies knowledge gaps, and informs not only GP practice but also research and policy about ways to improve the quality of care. higher risk of MHDs than patients without ID. [23][24][25][26] Primary care databases show a prevalence of MHDs in adult patients with ID ranging from 21%-34%. 4,23,[25][26][27] GPs' screening of patients with ID or MHD identified 33%-71% of patients as having a possible MHD and needing further medical assessment. [28][29][30][31] Severe mental illnesses such as schizophrenia, bipolar disorder, and psychosis are more prevalent in patients with ID. 3,4,23,32,33 Depression and anxiety are recorded less, 33,34 equally, 4,34 or more often, 23 with an earlier age of onset for depression. 35 Smoking, alcohol, and other substance use are less prevalent, 23,33 but alcohol misuse is more prevalent in patients with ID. 23

Thematic results
Thematic analysis revealed five overarching themes: GP roles, knowledge and experience, caregiver roles, collaboration, and a standardised approach. The results are narratively presented accordingly. Box 1 presents the key findings per theme. GP roles. The publications reveal the GP as the key figure in the identification, initiation, and coordination of treatment of patients with ID and MHD. 31,[36][37][38][39][40][41][42][43][44][45] Several GP roles in the care for this patient group are described, however, with varying acceptance, experience, and fulfilment among GPs. 42, 46,47 The GP roles relate, in the first place, to 'prevention of MHDs', 32,43,44,48,49 in the sense of a 'proactive approach'. This comprises general health promotion and targeted education about healthy living or substance use, 32,44,49 but also identification of MHDprovoking risk factors and development of prevention strategies. 31,43,48,49 Second, GPs are expected to fulfil an important role in the diagnostic assessment of MHDs, which is described as challenging for GPs. 50 Indications of inaccurate diagnoses 48,51 and underdiagnosis in primary care are frequently reported 4,31,41,42,48,49,[52][53][54][55][56] and may result in inappropriate care and progression of the disorder to a more severe stage that is less responsive to treatment. 23,52,[57][58][59] Overdiagnosis occurs as well, however, leading to unnecessary prescriptions of medication. 53,57 Diagnostic failure is seen as related to communication problems, with patients with ID described as less able to label their feelings and communicate their needs, 44,53,57,60-62 resulting in an atypical presentation of symptoms 29 29,44 Third, regarding GPs' 'treatment role', it is indicated that GPs should be able to handle less complex MHDs in people with ID. 40,44,68 For this patient group the same requirements and treatment guidelines apply as for patients with MHD but without ID, 44,57,65,71,73 with the necessity to refer patients with more complex disorders to specialised care. 44,68 GPs prescribe psychotropic medication to a higher number of patients with ID (17%-63%) than other patients. 4,74,75 In addition, a higher number of patients with ID are reported with psychotropic prescriptions than with recorded MHDs, indicating offlabel prescription. 4,39,44,49,[75][76][77][78][79][80] Behavioural problems are often described as an indication to start medication, 4,39,59,73,74,78,79 specifically in cases of limited access to alternative treatment strategies. 4 Prescribed medication is reported as predominantly long-term medication, 75 and a large proportion (62%-70%) is prescribed without a psychiatrist's involvement. 50,51,81 Medication prescription can be considered part of a multidisciplinary and holistic care plan; 65 however, in primary practice, GPs are less likely than psychiatrists to provide psychosocial interventions. 72 Finally, 'follow up' by GPs is considered an essential element in the treatment of patients with ID and MHD. 48,50,65,69,73,[82][83][84] It enables the monitoring of treatment responses and possible adverse side effects, leading to early adjustment of the treatment plan. 50,73 However, a lack of effective monitoring of psychotropic medication by GPs is often described. 28,42,51,55,74,81,85,86 It is stipulated that this relates to GPs' lack of specific experience and knowledge, 51,81,87 uncertainty about who of the involved professionals is responsible for follow-up, 47 50 It is indicated that limited knowledge and experience create feelings of insecurity in GPs when addressing patients with ID and MHD, 50 lack of caregivers' confidence in the GP, 52 and insufficient care. 37,41,44,52,58,66,81,91,92,97 Although GPs are interested in more training and education regarding patients with ID and MHD, 24,37,41,42,44,52,58,66,87,90,91 in practice it is seen as a challenge to engage them, caused by the small size of the population and the variety of competing medical issues. 58,70 Publications underline the importance of investment in more research and initiatives for effective training, skill development, 37 49,50,73,82 A symptoms checklist is mentioned as a helpful tool for caregivers to provide the GP with the information needed. 40, 73 Furthermore, it is noted that the referral process can be complex, and support by caregivers can be essential to prevent delay in care. 96,100 In addition, the GP is reliant on caregivers understanding symptom presentation, 29 57,63,73 It is indicated that the more severe the ID, the more reliant the GP is on caregivers. 63 Therefore, GPs should determine the key people in a patient's life 73 and proactively involve them. 49,72 However, GPs should also realise that some caregivers may give information from their personal perspective, use different definitions of medical terms than the GP, 44 49 GPs' options include referral for collegial advice, 31,48,72,94 handing the patient over to other professionals, 44 or joining a multidisciplinary team giving integrative care to the patient. 93,98,101 The latter is described as particularly desirable when the patient has a more severe ID or is in a highly complex situation. 39,44,99 Effective collaboration is seen as beneficial for the outcome of mental health care in primary care 28 Particularly in cross-domain collaboration, it may be unclear who is involved, how responsibilities are shared, and how care is financed. 47,83,86,88,89,96,104 It is mentioned that adequate division of responsibilities may depend on the main causal factor(s) of the MHD and may necessitate using care plans and convening case conferences. 68 Responsibilities should be clearly stated in writing and reviewed regularly. 88 Consequently, suggested preconditions for effective collaboration are accessible referral options, clarity about referral procedures, adequate information exchange between the professionals, and consensus on responsibilities. 3,24,39,41,88,94,96,107 It is noted as a barrier that, from a historical point of view, primary and secondary care services are separate units culturally, 98 organisationally, 42 and financially. 96,98,101 To improve the quality of collaboration, the roles of both GPs and other involved professionals should be defined more clearly, 60,72 existing models should be evaluated, 42,109 clinical pathways and/or models should be improved, 24,42,109 specialist capacity should be enhanced, 41 and payment models should be re-examined to stimulate collaborative care. 98,101 Policymakers' involvement in this matter is seen as important. 98,101 A standardised approach. In several publications, a standardised approach is seen as a way to improve the quality of care for patients with both ID and MHD. [43][44][45]49,50,65,68,83,110 First, standardised screening for MHDs gives GPs the opportunity to consider potential mental health issues at an early stage. 44, 49 Second, a structured multidimensional approach in the assessment leads to more appropriate and accurate diagnosis, treatment, and referral. 44,45,49,65,68 Finally, systematic and standardised medication prescriptions and reviews identify potential medication-related problems at an early stage. 43,50,65,83,110 Although guidelines and instruments are available to support GPs in applying a standardised approach in the general population, they are often not adapted to patients with ID. 40,43,44,72,73,80 Some publications covered specific guidelines for prescribing and/or monitoring medication for MHDs in patients with ID, 39,47,49,54,59,65,67,73,82 and applicable tools for detecting unmet health needs in patients with ID. 31,40,49,60,69 It is suggested that GPs are insufficiently familiar with these ID-specific guidelines and tools. 51,87

DISCUSSION Summary
To the authors' knowledge, this is the first scoping review with a focus on patients with both ID and MHD in primary health care. GPs are a key figure in the care for this specific patient group. They have a broad role that can be demanding in the sense that GPs need specific knowledge, experience, and skills for a relatively small patient group. The publications indicate that current GP care is often of an insufficient standard, as reflected in underdiagnosis of MHDs, overmedication, and lack of effective patient follow-up. Gaps are identified regarding effective training programmes for GPs, applicable guidelines and tools, optimal collaborative mental health care, and corresponding payment models. Opportunities for improvement are seen in prioritising and investing in bridging these gaps. This requires the involvement not only of care professionals and scientists, but also of policymakers.

Strengths and limitations
The first strength of this review is that a robust and widely accepted scoping review method 19 was used to provide a solid overview of the existing knowledge on GP care for patients with both ID and MHD. Second, only publications from countries where GPs have a gatekeeper role were included. This results in recommendations that can improve not only the quality of GP care, but also the overall mental health care for patients with ID. Finally, to prevent dispersion of the results of an already broad research question, this study focused on adults, thereby giving attention to a vulnerable group that is potentially more overlooked than children.
This review also has limitations. First, a lack of consistency was found in the definition of ID, as many publications did not supply a clear definition of it. This limitation reflects the heterogeneity of the patient group, and results should be interpreted accordingly. Second, the publications retrieved in the grey literature search are presumably not perfectly complete, despite the use of the 'Grey Matters' tool 21 and checking references lists. Some publications were not accessible for the research team, and publications could have been missed because of the great diversity of possible sources.

Comparison with existing literature
The results of this review indicate that patients with ID constitute a small group within the GP population, accounting for the low priority of this group in education and research. 58,70 However, this claim regarding the proportion of patients is debatable. In the Netherlands, it is estimated that 6.4% of the population have a mild ID. 1 Research in primary care data shows that no more than 0.56% of GPs' clients are registered as having an ID. 23,34 This could be an indication of GPs' insufficient recognition and underestimation of the size of the ID population. This underestimation is also present in mental health care and is a reason for concern. 7 Identification of an ID is essential both for good care provision and for treatment success in MHDs. 14 Helpful ID screening tools have been developed for GPs when they are considering an ID, but further implementation in practice is needed. 111,112 The results from this study revealed two strategies to improve care for patients with both ID and MHD: adequate medical training and applicable evidence-based guidelines and tools. This is in line with previous reports and publications concerning general health issues in patients with ID. 12,113 It is also suggested that GPs should use the same treatment guidelines for mild or less complex MHDs in patients either with or without ID. 44,57,65,71,73 However, research to substantiate this is scarce, and research in addiction care shows that alterations in the treatment programmes for substance use disorders are needed for patients with ID. 10 Furthermore, previous research projects have led to practical primary care tools, such as the Psychiatric Assessment Schedule for Adults with Developmental Disabilities (PAS-ADD). 31,60 However, these tools are not fully implemented in primary care.
This review identified various kinds of primary care collaborations in which GPs participate, and shows that effective collaboration can improve care; the latter is widely supported and confirmed by the World Health Organization. 114 This review had an international focus, and the possibilities of multidisciplinary approaches in primary care differ in the various healthcare systems. Within the ambitions and possibilities of the NHS, the UK sees integrated care systems as an important tool for improving health care and for reducing inequalities between different groups of people, 115 and has long-term experience with community learning disability teams. These multidisciplinary teams provide health care and advice to people with ID, GPs, carers, families, and to the wider health and social care community. 116 Another example of promising collaboration in daily practice is 'The DD Health Home' in the US. This care model provides integrative routine care to patients with ID and MHD, including primary care and structural follow-up. 98 Despite these best practices, there is at present limited scientific evidence on the effectiveness of these collaborative (mental) healthcare services for persons with ID. 117 Preconditions for collaborative care, as listed in Box 1, are also recognised in older people and chronic disease care. [118][119][120] All these disciplines mention adequate reimbursement as a critical barrier to successful collaboration, and reimbursement needs to be prioritised. Additionally, collaboration is more effective when there is a team vision, shared goals, formal quality processes, and shared ICT information systems. 118,120 Research in older person care has revealed that GPs are indispensable in multidisciplinary teams regarding networking activities, integration of care, and showing leadership; the researchers stress that GPs should be made more aware of this, for instance, in GP training programmes. 121 Finally, the results of this review stress the importance of the GP collaborating with caregivers. Remarkably, none of the included publications focused on patients' needs in their contact with the GP, although research shows that people with ID prefer to be less reliant on caregivers in GP consultation and argue for an improvement of the accessibility of health services. 13,122,123 The UK National Institute for Health and Care Excellence guideline Mental Health Problems In People With Learning Disabilities: Prevention, Assessment And Management gives special attention to the involvement of people with ID and their caregivers in organising their care. In addition, this guideline covers mental healthcare in a holistic way in different UK settings, and may serve as an example for other countries. 124 Implications for research and practice Improvement of care for patients with both ID and MHD needs to be prioritised, justified by the limited quality of care and the substantial size of this patient group. This improvement cannot be achieved by GPs and their collaborative partners alone. It requires adaptations on both the organisational and the political level. However, it remains important to actively engage GPs to ensure that suggested strategies are applicable and feasible in daily practice.
Diverse improvement strategies are advisable. First, it is important to invest in effective, frequently recurring postcurriculum training programmes for GPs, focusing on more awareness of this patient group, specific knowledge gaps regarding IDs and MHDs, existing tools and guidelines, and GP roles in multidisciplinary teams. Offering training programmes in an interprofessional setting can support the latter and will additionally promote collaboration between care professionals.
Second, ongoing policy changes, such as the move to integrated care systems in the UK, and best practices such as the community learning disability teams in the UK, provide opportunities for further development of optimal collaborative healthcare models for patients with both ID and MHD. Policymakers should re-examine payment models to create incentives for collaborative care, facilitate shared ICT information facilities, and involve potential users in the development of these healthcare models. Third, although the increase in publication over the recent years is a positive sign, more research is still needed on the effectiveness of existing general mental health guidelines and tools to determine whether they are truly applicable to patients with ID or whether specific alterations are needed. Priority should be given to guidelines and tools on MHD assessment, the prescription of psychotropic medication, and patient follow-up. Finally, further research should focus on the needs of caregivers in supporting patients, as well as on the needs of patients with both ID and MHD and how they can enhance their autonomy in GP contacts.
This scoping review illustrates GPs' vital roles in the care of patients with both ID and MHD. Current GP care has generally proved insufficient, and improvement strategies are needed in close collaboration with policymakers and organisational managers. Multidisciplinary approaches in primary care -like those in the UK and US -seem promising, but still lack sufficient scientific evaluation. Investment in education, evidence-based guidelines and tools, and collaborative healthcare models is essential. This, supplemented with enhanced ID identification and attention to the needs of patients and their caregivers, may significantly improve the quality of care for this vulnerable patient group.

Funding
This research was supported by the Netherlands Organization for Health Research and Development (ZonMw; grant 641001100), care institution's Heeren Loo, and the Ds J.A. Visscher foundation.

Ethical approval
None required.

Data
Qualitative data are available from the corresponding author upon reasonable request.

Provenance
Freely submitted; externally peer reviewed.

Competing interests
The authors have declared no competing interests.