Study of concomitant antipsychotic use - Part 2 (only available in French)

Retrospective cross-sectional cohort study

Background

The Conseil du médicament was asked to document the use of antipsychotics by the Québec population, focusing primarily on the concomitant use of multiple antipsychotics. This request follows two investigative reports from the coroner regarding schizophrenic patients treated with combination antipsychotic therapy. Part 1 of this study addressed concomitant antipsychotic use by the general population.

Objectives

Part 2 of this study is aimed at determining the prevalence of antipsychotic use, the proportion of combination antipsychotic therapy and the variety of antipsychotic combinations by psychopathology group among children, adolescents and young adults. 

Methods

A retrospective cross-sectional cohort study was carried out with individuals who had ongoing coverage between January 1 and December 31, 2006, under the Public Prescription Drug Insurance Plan administered by the Régie de l’assurance maladie du Québec (RAMQ). Two types of populations were taken into account in this study:  

• children and adolescents who are dependents of beneficiaries and beneficiaries aged 24 and under;
• children and adolescents who are dependents of recipients of last-resort financial assistance and young adults aged 24 and under who are receiving last-resort financial assistance.

Information regarding the drugs administered to insured individuals as well as socio-demographic and medical information (medical services and associated diagnostic codes) for these individuals was obtained from RAMQ computer files. A descriptive analysis of individuals insured by the Public Prescription Drug Insurance Plan and antipsychotic users was conducted according to the type of antipsychotic used, the type of therapy (monotherapy or combination therapy), the duration of therapy (long term: 60 or  more consecutive days; short-term: less than 60 consecutive days), the type of antipsychotic combination (bi-, tri- and tetratherapy), age group, gender, health region, and five mutually exclusive groups of mutually exclusive primary psychiatric diagnoses.

Results

In 2006, the overall prevalence of antipsychotic use among individuals aged 24 and under was 1.5%. Among the 8,391 antipsychotic users aged 24 and under who were studied, 6% received long-term (60+ days) combination therapy at least once during the year. The proportion of atypical (second-generation) antipsychotic use was very high, at 95% of users. When antipsychotic users were categorized sequentially according to the 5 mutually exclusive diagnosis groups, 1,487 users were diagnosed with schizophrenia, 1,030 had organic and non-organic mental disorders, 996 had pervasive developmental disorders (PDD), 1,586 had disruptive behaviour disorders and 2,129 had mood disorders. A large majority of these individuals had more than one psychiatric diagnosis, and the use of long-term combination antipsychotic therapy varied between 4.75% and 24.12% depending on the groups of pathologies considered.

Conclusion

Despite a lack of official indication as to the use of antipsychotics, specifically atypical (second-generation) antipsychotics, in pediatrics, these drugs are nevertheless prescribed in Québec in a variety of clinical situations. The prescription of combinations of multiple antipsychotics to individuals aged 18 and under and to young adults for long periods of time without these combinations being supported by clinical evidence gives cause for concern and highlights the need to establish guidelines for antipsychotic use among children, adolescents and young adults.