Évaluation de l’utilisation et des coûts des soins de santé psychiatriques associés à l’autisme au Québec et impact de l’usage des médicaments psychoactifs dans la survenue de l’obésité chez les jeunes autistes

Introduction: Optimizing the use of psychiatric healthcare for young people with autism is of great importance because of the increased prevalence of diagnosed cases, the associated costs to the health system, and the potential and not well characterized impacts of the off-label use of multiple psychoactive medications on the health of these young people in the long term. In this perspective, three studies were conducted to 1) characterize the evolution in usage of psychoactive drugs in young people with autism over a period of 5 years following their diagnosis; 2) to describe psychiatric healthcare utilization and associated costs for these youths during the same time period; 3) to evaluate the association between the use of psychoactive drugs and the occurrence of obesity among autistic young people. Methods: For the first and second objectives, a cohort of newly diagnosed autistic youth (incident cases), 25 years of age or younger between 1998 and 2010 was extracted from the medico-administrative databases of the Quebec Public Health Insurance Plan (RAMQ). For those covered by the public drug plan, the use of psychoactive drugs and polypharmacy, other psychiatric healthcare services paid on a fee for service basis (hospitalizations, medical visits) and their associated direct costs were evaluated up to 5 years after diagnosis, as well as stratified by age group. Predictors of the use of different classes of psychoactive drugs, other psychiatric healthcare services and associated costs were assessed. For the third objective, a nested case-control study was conducted in a cohort of young autistics aged 18 years and under (prevalent cases) identified from the RAMQ database between 1993 and 2011 to identify predictors of new-onset obesity.  Potential predictors evaluated in this study included residential area, welfare status and the presence of other neuropsychiatric disorders. The impact of different classes of psychoactive medications was evaluated and the dose-response curve for atypical antipsychotics was explored.   Results: A cohort of 2,989 newly diagnosed autistic youths, covered by the public drug plan, was identified. In this cohort, the prevalence of psychoactive drug use increased from 35.6% in the year preceding the first diagnosis to 53.2% 5 years after diagnosis. The prevalence of psychoactive polypharmacy also increased from 9% to 22% during this period. Age and time since diagnosis were strongly associated with the types and combinations of psychoactive drugs prescribed. Use of other psychiatric healthcare services was evaluated in the 1,227 individuals who were continuously covered under the public drug plan during this same period. The average annual number of annual psychiatric medical visits reimbursed on a fee-for-service basis decreased more than three-fold (7.5 vs 2.1 visits; p<0,0001) from the first to the fifth year of follow-up. Psychiatric hospitalizations also decreased but represented the highest costs per person (CAD $ 9,820 for year 1 and CAD $ 4,628 for year 5; p<0,0001) during that same period. Psychiatric healthcare utilization and associated costs varied according age, the presence of psychiatric comorbidities, welfare status and use of psychoactive drugs in the year preceding autism diagnosis. Specifically, previous use of psychoactive medications was associated with an increase in psychiatric healthcare costs at 5 years (OR: 1.71, 95% CI: 1.32-2.22). Among the 5,369 young people diagnosed with autism before the age of 18, of the potential predictors studied, only the use of atypical antipsychotics was associated with an increased risk of obesity compared to non-users. Higher risk was observed with chlorpromazine equivalent daily doses ≥100mg (RR:2.20 95%CI (1.00-4.84)). Among atypical antipsychotic users, concomitant antidepressants (per 30-day exposure) also increased the probability slightly (RR:1.08 95%CI (1.01-1.15)).   Conclusion: Based on real-world data, among individuals covered by the public drug plan, the analysis of psychoactive medications and other psychiatric healthcare utilization by autistic youths highlights important resource implications for the health system. The increasing use of psychoactive medications, which could also contribute to obesity issues among young people with autism, contrasts with the paucity of evidence supporting long term psychoactive medication use in these children. This practice could be of concern if used in lieu of other non-pharmacological treatment modalities. Our results underline the importance of carrying out research to identify drug and non-drug therapeutic approaches that provide optimal, long term care. This, in terms of optimizing resources for the healthcare system and increasing the quality of life of people with autism and their families.

Keyphrases: Psychiatrie, Autism, Psychoactive Medication, Antipsychotics, Healthcare Utilization, Psychiatry, Costs, Predictors, Obesity