Introduction
The use of antipsychotic medications in adults with Intellectual and Developmental Disabilities (IDD) is a subject of considerable debate within healthcare. This controversy stems from limited evidence supporting their effectiveness when a co-occurring psychiatric condition is absent, coupled with significant concerns about potential adverse effects. While efforts have been made to curb inappropriate antipsychotic use in vulnerable populations like children, youth, and older adults with dementia, less attention has been directed towards adults with IDD, despite their vulnerability. This population commonly experiences both psychiatric disorders and challenging behaviors. International data reveals frequent antipsychotic prescriptions for adults with IDD, often targeting both psychiatric symptoms and behavioral issues. However, long-term efficacy data for managing challenging behaviors is lacking, and short-term evidence remains inconclusive. Adding to the complexity, antipsychotics carry a high risk of side effects, particularly metabolic complications. Adults with IDD face additional challenges in informed consent and reporting adverse effects due to communication, cognitive, and memory impairments, alongside frequent medical comorbidities. Therefore, ensuring appropriate antipsychotic use within this population is crucial. This study investigates the prevalence and characteristics of antipsychotic use among adults with IDD in Ontario, Canada, with a specific focus on comparing profiles of individuals with and without a documented psychiatric diagnosis to better understand the landscape of Antipsychotic Diagnosis and prescription in this population.
Methods
This population-based cohort study was conducted as part of the Health Care Access Research and Developmental Disabilities (H-CARDD) Program. We established a cohort of 66,484 Ontario adults aged 18–64 years with an IDD diagnosis as of April 1, 2009, by linking provincial health and social services data. IDD identification was based on diagnostic codes in physician and hospital claims, or disability benefit eligibility records. The study included 51,881 adults with IDD eligible for public drug benefits and alive on April 1, 2010, who were followed for six years until March 31, 2016, to determine antipsychotic medication dispensation. A sub-cohort of 7,219 adults residing in group homes was also identified. The index date was defined as the date of the first antipsychotic prescription during the study period.
Data sources included the Ontario Drug Benefit (ODB) claims database for prescription medication data, and databases from the Canadian Institute for Health Information (CIHI) and Ontario Mental Health Reporting System (OMHRS) to identify psychiatric diagnoses from hospitalizations, emergency department visits, and mental health hospitalizations. The Ontario Diabetes Database and Ontario Hypertension Database were used to determine pre-existing diagnoses. The Ontario Health Insurance Program (OHIP) claims database provided psychiatric diagnoses from physician visits, and the Registered Persons Database provided demographic data. Data were linked using encoded identifiers and analyzed at the Institute for Clinical Evaluative Sciences (ICES).
Psychiatric diagnosis was defined as having a major mental illness (schizophrenia, non-schizophrenia psychotic disorder, bipolar disorder, or major depressive disorder) or another psychiatric diagnosis (other depressive, anxiety, somatoform, dissociative, psychosomatic, personality, adjustment, conduct, or impulsivity disorders) within the two years before the index date, recorded in OHIP, DAD, SDS, or OHMRS databases. This classification allowed for analysis of antipsychotic diagnosis categories: those with major mental illness (clear psychiatric indication), those with other psychiatric diagnoses (potential psychiatric indication), and those with no psychiatric diagnosis.
Sociodemographic and clinical characteristics measured at the index date included sex, age, urban residence, and neighborhood income. Previous medication use (one year prior), comorbidity (Charlson Comorbidity Index using three-year hospitalization data), physician services (visits in the past year and 90 days), and health service utilization (emergency department visits and hospitalizations in the past two years) were also assessed.
Prevalence of antipsychotic prescribing was calculated for the entire cohort and annually. Comparisons between groups with and without psychiatric diagnoses were made using standardized differences, with values greater than 0.1 considered meaningful. Analyses were conducted using SAS version 9.4.
Results
Out of 51,881 adults with IDD, 20,316 (39.2%) were dispensed at least one antipsychotic medication between April 1, 2010, and March 31, 2016, incurring a total cost exceeding $117 million CAD. Among adults with IDD in group homes, 56.4% (4,073 of 7,219) received antipsychotics. Annual prevalence remained relatively stable throughout the study period. Atypical antipsychotics accounted for 84.1% of prescriptions, with oral quetiapine, risperidone, and olanzapine being the most common. In group homes, risperidone was most frequently dispensed, followed by quetiapine.
Antipsychotic users had an average age of 42 years, were predominantly male (58.8%), and resided in urban areas (85.0%). They were dispensed a median of seven drugs in the preceding year, with antidepressants (48.4%) and benzodiazepines (40.6%) being frequently used. A significant proportion (62.3%) had at least one emergency department visit in the past two years, and 76.4% had physician visits in the last 90 days.
Just over two-thirds (71.1%) of antipsychotic users had a documented psychiatric diagnosis in the two years before prescription, with only 39.9% having a major mental illness. Those without a psychiatric diagnosis were slightly older, of higher socioeconomic status, and less likely to live in urban areas. They were less likely to have used antidepressants or benzodiazepines but more likely to have used lithium or antiepileptic drugs previously. Healthcare service utilization was higher among those with a psychiatric diagnosis. Notably, a significantly larger proportion of individuals with a psychiatric diagnosis had visited a psychiatrist within 90 days prior to antipsychotic prescription (39.9% vs 6.4%), highlighting the role of antipsychotic diagnosis in this group.
Sub-Analysis: Group Home Residents
Among group home residents receiving antipsychotics (n=4,073), the average age was 45 years, and most were male (63.1%). Only 57.1% had a psychiatric diagnosis, and only 21.9% had a major mental illness in the preceding two years. Similar to the overall cohort, differences in medication use and healthcare utilization between those with and without psychiatric diagnoses mirrored the broader findings.
Discussion
This large-scale study reveals a high prevalence of antipsychotic use among adults with IDD in Ontario, with two in five individuals receiving these medications over a six-year period. The rate is even higher in group homes, exceeding half of the residents. This prescribing pattern carries substantial financial implications, costing the province over $117 million CAD during the study period. A significant finding is that a large proportion of antipsychotic users, almost 30%, did not have a documented psychiatric diagnosis. This subgroup exhibited distinct demographic and clinical profiles compared to those with a diagnosis, being older and less likely to have recent histories of antidepressant or benzodiazepine use, or frequent healthcare interactions. This raises concerns about the appropriateness of antipsychotic diagnosis and prescribing practices for adults with IDD, particularly when a clear psychiatric condition is not evident.
Our findings align with international research indicating antipsychotic prescribing rates in adults with IDD ranging from 21% to 45%, with a substantial proportion prescribed without a recent psychiatric diagnosis. A comparable UK study reported a lower percentage (29%) of antipsychotic users having a serious mental illness diagnosis, even with incentives for recording psychiatric diagnoses. While our study showed a slightly higher rate (40% with major mental illness), our definition included major depressive disorder. Interestingly, the UK study observed a declining trend in antipsychotic prescriptions, potentially reflecting the impact of interventions to reduce inappropriate prescribing, contrasting with the stable prevalence in our study. The UK’s recognition of ID psychiatry as a subspecialty and availability of community-based IDD teams for non-pharmacological interventions, which are less prevalent in Ontario, may contribute to these differences. Cross-jurisdictional comparisons highlight the influence of policy and practice approaches, including specialized training, on prescribing patterns.
The even higher antipsychotic use in group homes, where over half of residents were prescribed these medications, warrants further investigation. While diabetes and hypertension rates were slightly lower in this subgroup, suggesting potential benefits of residential care in chronic disease prevention, a concerning 42.9% of group home residents receiving antipsychotics lacked a recent psychiatric diagnosis. This points towards potential off-label use in a significant proportion, emphasizing the need for research into antipsychotic use within residential care settings. Systemic factors like staffing and environmental characteristics may influence prescribing practices in group homes alongside clinical needs. Targeted interventions, including guidelines, training for prescribers and pharmacists, and monitoring within residential care, are crucial, given staff knowledge gaps about antipsychotics and their associated harms.
The high antipsychotic use, especially in the absence of a psychiatric diagnosis, necessitates critical reflection on the driving factors and strategies to ensure appropriate and safe prescribing. Funding mechanisms in Ontario, where medications are covered but psychological interventions and behavior therapy are not, may contribute to this issue. Limited access to specialized psychiatric support for IDD in Ontario and Canada, coupled with insufficient training in IDD psychiatry, can lead to misdiagnosis and inappropriate antipsychotic prescriptions. Further research is needed to comprehensively understand the multifaceted factors contributing to antipsychotic prescribing practices in Canada to inform effective interventions.
This study’s strengths include its large population-based cohort and linked databases, providing a broad view of prescribing practices beyond service users or primary care settings. However, limitations include the inability to assess antipsychotic effectiveness or medication monitoring quality. While polypharmacy is suggested by the high number of dispensed medications, specific medication combinations and durations are unknown. Determining whether antipsychotics were prescribed for challenging behaviors in the absence of psychiatric diagnosis was not possible through database analysis alone. While our psychiatric diagnosis definition is broad and consistent with prior studies, misclassification due to uncaptured diagnoses in billing data is possible, though unlikely to significantly impact findings. The study’s focus on adults aged 18-64 in 2009 may limit generalizability to older adults or youth. Residential status was assessed in 2009, and changes over time were not tracked, although group home residence is generally stable in Ontario. Diagnostic coding specificity did not allow for sub-categorization by IDD type or severity. Finally, non-pharmacological interventions were not examined.
Conclusions
The significant antipsychotic use among adults with IDD in Ontario, particularly the high proportion without a psychiatric diagnosis, raises concerns about potentially inappropriate prescribing. Future research and policy efforts in Canada should prioritize assessing the appropriateness of antipsychotic prescribing in this vulnerable population, including chart audits and feedback mechanisms. Long-term risk-benefit research is essential. Collaboration among psychiatry, pharmacy, and policy experts across jurisdictions is needed to align antipsychotic use with clinical guidelines and ensure optimal healthcare for adults with intellectual and developmental disabilities.
Acknowledgments
We gratefully acknowledge the Province of Ontario, IMS Brogan Inc, and CIHI for their support and data contributions to this study.
Footnotes
Declaration of Conflicting Interests: The authors declare no conflicts of interest.
Funding: This study was supported by the Institute for Clinical Evaluative Sciences (ICES), funded by an annual grant from the Ontario MOHLTC.
References
References from original article should be included here. (To be added if full reference list is required).
