Purpose: To investigate associations between antidepressant use patterns and risk of fatal and non-fatal suicidal behaviours in older adults who initiated antidepressant therapy.
Method: A national population-based cohort study conducted among Swedish residents aged ≥ 75 years who initiated antidepressant treatment. Patients who filled antidepressant prescriptions between January 1, 2007 and December 31, 2013 (N = 185,225) were followed until December 31, 2014. Sub-hazard ratios of suicides and suicide attempts associated with use patterns of antidepressants, adjusting for potential confounders such as serious depression were calculated using the Fine and Gray regression models.
Results: During follow-up, 295 suicides and 654 suicide attempts occurred. Adjusted sub-hazard ratios (aSHRs) were increased for both outcomes in those who switched to another antidepressant (aSHR for suicide 2.42, 95% confidence interval 1.65 to 3.55, and for attempt 1.76, 1.32 to 2.34). Elevated suicide risks were also observed in those who concomitantly filled anxiolytics (1.54, 1.20 to 1.96) and hypnotics (2.20, 1.69 to 2.85). Similar patterns were observed for the outcome suicide attempt. Decreased risk of attempt was observed among those with concomitant use of anti-dementia drugs (0.40, 0.27 to 0.59).
Conclusion: Switching antidepressants, as well as concomitant use of anxiolytics or hypnotics, may constitute markers of increased risk of suicidal behaviours in those who initiate antidepressant treatment in very late life. Future research should consider indication biases and the clinical characteristics of patients initiating antidepressant therapy.
Keywords: Aged; Antidepressants; Cohort study; Pharmacoepidemiology; Suicide.