A Post-Authorization Safety Study of Quetiapine as Antidepressant Treatment in Sweden: Nested Case-Control Analyses of Select Outcomes.

INTRODUCTION: This post-authorization safety study (PASS) was a commitment to the European Medicines Agency. OBJECTIVE: This PASS investigated quetiapine as antidepressant treatment in Swedish registers with regard to the risk for all-cause mortality, self-harm and suicide, acute myocardial infarction, stroke, diabetes mellitus, extrapyramidal disorders, and somnolence. METHODS: Users of quetiapine and antidepressants (2011‒2014) who had changed treatment in the past year were included. Conditional logistic regression models were used to calculate odds ratios (ORs) and their 95% confidence intervals (CIs) for each outcome in nested case-control studies for quetiapine as combination therapy and monotherapy, monotherapy with antidepressants, and no medication, versus the use of combinations of antidepressants (reference group). RESULTS: Overall, 7421 quetiapine users and 281,303 antidepressant users were included. For quetiapine in combination, risks were increased for all-cause mortality [adjusted OR (aOR) 1.31, 95% CI 1.12-1.54] compared with combinations of antidepressants; however, when stratified by age, only patients ≥ 65 years of age had an increased mortality, and, in a post hoc analysis excluding patients with Parkinson's disease, no mortality increase remained. Furthermore, the risk for self-harm and suicide was increased (aOR 1.53, 95% CI 1.31-1.79), but when stratified by age, the risk increase was found only among patients aged 18-64 years. Risks were also increased for stroke among patients ≥ 65 years of age (aOR 1.47, 95% CI 1.01-2.12), for extrapyramidal disorder (aOR 6.15, 95% CI 3.57-10.58), and for somnolence (aOR 2.41, 95% CI 1.42-4.11). CONCLUSION: Risks for all-cause mortality, self-harm and suicide, and stroke in older patients may be higher among patients treated with quetiapine and antidepressant combination therapy.