Discontinuation of antidepressants: Is there a minimum time on treatment that will reduce relapse risk?

BACKGROUND: Several national guidelines include recommendations for a minimum duration of antidepressant treatment, but these vary from 4-9 months after remission. We aimed to investigate whether there is an optimal minimum duration of antidepressant treatment to reduce relapse risk. METHODS: A Danish population-based cohort study among 89,442 adults who initiated antidepressants for depression treatment aged 18-60 years, from 2006-2015. We defined antidepressant discontinuation as ≥30 days without treatment. We estimated hazard ratios (HRs) with 95% confidence intervals (CIs) to indicate the risk of restarting antidepressants among those who discontinued antidepressants with <4, 4-6, and 7-9 months of use compared with discontinuation after 10-12 months. RESULTS: For individuals on antidepressant treatment <4, 4-6, 7-9 and 10-12 months, cumulative incidence of restarting treatment within one year was 37.4% (95% CI: 36.9-37.8%), 35.1% (95% CI: 34.6-35.7%), 35.0% (95% CI: 34.2-35.8%) and 32.8% (95% CI: 31.7-34.0%), respectively. Individuals on antidepressants <10 months versus 10-12 months had higher risk of restarting antidepressants: the HR for antidepressant treatment <4 months was 1.21 (95% CI: 1.16-1.27), 4-6 months 1.11 (95% CI: 1.06-1.17), and 7-9 months 1.09 (95% CI: 1.04-1.15). LIMITATIONS: We were not able to ascertain the reasons why individuals discontinued antidepressants, and systematic errors from unmeasured confounders cannot be ruled out. CONCLUSIONS: Based on our findings, a minimum of 10-12 months of treatment appears to be preferable if there is concern about relapse after discontinuation.