The association between antidepressant use and depression eight years later: a national cohort study

Investigations of the effects of antidepressant treatment for individuals with major depression have focused on short-term outcomes in individuals that meet very specific criteria; however, there is limited knowledge about long-term outcomes associated with antidepressant use in general population samples. This study aimed to investigate the long-term outcomes associated with antidepressant use by focusing on 486 depressed adults in a prospective observational Canadian cohort in 1998/99. We used logistic regression to investigate the association between antidepressant use and depression status 8 years later. Non-random allocation to treatment was accounted for by a propensity-for-treatment model which included thirteen predictors of antidepressant use, including: severity of depressive symptoms, previous episodes of depression (from 1994 to 1997), physical health condition, social support and socio-demographic characteristics. 29% of individuals with major depression reported antidepressant use. After adjusting for propensity for treatment in 1998/99, and antidepressant use from 2000 to 2007, depressed individuals who reported antidepressant use in 1998/99 were less likely to be depressed in 2006/07 compared to those who did not report antidepressant use (OR = 0.36, 95% CI: 0.15-0.88). Amongst individuals with symptoms of major depression, those reporting use of anti-depressants at baseline exhibited improved long-term outcomes in comparison to those who did not report treatment.