Number of visits to the emergency department predicts suicide risk: A nested case-control study

Background/Purpose: Patientxs contact with the emergency department (ED) preceding a suicide may offer opportunity for prevention. However, parts from patients presenting with mental diseases or self-harm, potential suicide victims are difficult to detect at the ED. The aim was to evaluate whether number of visits to the ED is associated with suicide. Methods: The cohort comprised 107,190 patients paying 258,025 visits during 2002-2008, who were discharged home. The suicide cases (n=152) were identified through record linkage, based on personal identifier, of the cohort with nationwide death registry. Ten times as many controls were randomly selected from the cohort using risk set for each case. Information on baseline/exposure factors: age, gender, personal identifier, date, time, registration number, and diagnosis were obtained from computerized ED register. Odds ratio (OR) and 95% confidence intervals (CI) were calculated by multivariate logistic regression. Results: Suicide cases had on average attended four times to the ED while controls attended twice. The OR for attendance due to mental and behavioral disorders was 3.11 (95%CI 1.63-5.93), 1.55 (95%CI 1.02-2.36) for non-causative diagnosis, and 14.09 (95%CI 2.62-75.91) for poisoning. The ORs increased gradually with increasing number of visits, adjusted for age, gender, and the above mentioned diagnoses. For seven or more ED visits the adjusted OR was 6.74 (95%CI 3.42-13.31) compared to those who had one visit. Conclusion: Number of visits to the ED is an independent risk factor for suicide adjusted for known, important risk factors. This new risk factor may open for new means for suicide prevention.