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.