Development of a Typology of Antidepressant Users: The Role of Mental Health Disorders and Substance Use.

Background/objectives: Antidepressants constitute one of the most consumed classes of psychotropic medication. This study aims to identify a typology of users based on their individual characteristics, such as presence of a mental disorder and use of other psychotropic medication during the last year.

Methods: Antidepressant use for residents in the epidemiological zone of South-West Montreal aged 15 years and older was documented in 2009, 2011, and 2013. Among the 2433 participants from the initial study, 249 had used antidepressants (10%). A cluster analysis, validated with Chi-square tests and Cramer's V measure, was conducted with this sample. The longitudinal profile of the clusters was examined using curve clustering.

Results: Based on clinical variables measured at Time 1, four types of antidepressant users were identified (p<0,001; 0,58 ≤ V ≤ 0,81): depressed users without anxiety (15%), anxio-depressive users with substance dependence and polypharmacy (26%), depressed users with polypharmacy and being treated by a psychiatrist (31%) and users without mental health disorders (28%). Follow-ups two and four years later indicate a higher proportion of participants with symptoms of depression persisting over time within the cohort of persons having concurrent anxiety and substance dependence.

Conclusions: Results help improve knowledge about the context of antidepressant use in order to plan appropriate interventions. Depressed persons without anxiety appear to receive treatment from general practitioners, while those with comorbid psychotic disorders and depression may require specialized treatment from a psychiatrist. Anxio-depressive users with substance dependence and polypharmacy may require integrated services from different specialized networks in order to counter symptoms related to comorbidity.