Selective serotonin re-uptake inhibitors and the risk of violent suicide: a nationwide postmortem study

PURPOSE: We endeavored to investigate whether previous findings of an association between antemortem exposure to selective serotonin re-uptake inhibitors (SSRI) and method of suicide could be replicated. METHODS: Using the Swedish National Board of Forensic Medicine's toxicology database and the Swedish National Board of Health and Welfare's national registries of causes of death and prescriptions, 10,002 incidents of suicide were retrieved. Risks of violent suicide conferred by SSRIs, expressed as odds ratios (ORs) with 95% confidence intervals (CIs), were estimated using logistic regression. In accordance with previous work, suicide by violent means-cases-were defined as death attributable to causes designated by ICD-10 codes X70-X83 and Y20-Y33; and suicide by non-violent means-controls-by codes X60-X69 and Y10-Y19. RESULTS: Our results imply that SSRI exposure confers a risk of violent suicide for shorter treatment durations; and that antemortem exposure to other substances (including illegal drugs) confounds estimates of risk. After adjustment for age, sex, and other substances, SSRIs treatment not exceeding 28 days conferred an almost fourfold risk of violent suicide (OR 3.6 [95% CI 1.9-6.8]), a finding partly in line with a recent Swedish study that employed a case-crossover design. CONCLUSIONS: Although risks associated with shorter treatment duration may reflect latencies to onset of therapeutic effect, it is unclear how latencies would influence the choice of suicide method, unless conditions for which SSRIs are prescribed are themselves associated with violent suicide. Finally, in the total dataset, SSRIs were not associated with an increased risk of violent suicide; however, by adjusting for other substances, we avoided the spurious conclusion that the effect of medications in this regard is protective.