Risk of suicide and fatal drug poisoning after discharge from the emergency department: a nested case-control study

Objectives The objectives were to study the risk of suicide and fatal drug poisoning among emergency department users who had been discharged home, based on the main diagnoses selected by the emergency physician upon discharge. Methods This is a case-control study nested in a cohort of users of the emergency department who had been discharged. The cases of suicide (n = 41) and fatal drug poisoning (n = 21) were identified from the National Cause-of-death Registry, and five times as many controls were selected from users of the emergency department. Multivariate logistic regression analysis was used to calculate the OR and 95% CI adjusted for age and gender. Results Frequent visits to the emergency department were significantly associated with suicide and fatal poisoning. The study period spanned 7 years. The OR for suicide among cases and controls was 7.84 for those diagnosed as having mental disorders, 96.89 for those with use of alcohol, 24.51 for those with drug intoxication and 2.69 for those with a non-causative diagnosis. The OR for fatal poisoning for cases and controls was 12.26 for those with use of alcohol, 37.22 for those with drug intoxication and 5.76 for those with the classification category factors influencing health status. Conclusions The clinical implication is that patients with any combination of previous main diagnoses of mental disorder, alcohol use, drug intoxication, a non-causative diagnosis or with the classification category factors influencing health status should be evaluated and assessed for potential risk of suicide or fatal drug poisoning.