Subsequent suicide mortality among emergency department patients seen for suicidal behavior

Objectives: To determine whether suicide mortality rates for a cohort of patients seen and subsequently discharged from the ED for a suicide-related complaint were higher than for ED comparison groups. Methods: This was a nonconcurrent cohort study set at a university-affiliated urban ED and Level I trauma center. All ED patients 10 years and older, with at least one ED visit between February 1994 and November 2004, were eligible. ED visit characteristics defined the cohort exposure. Patients with visits for suicide attempt or ideation, self-harm, or overdose (exposed) were compared with patients without these visits (unexposed). Exposure classification was determined from billing diagnoses, E-codes (E950-E959), and free-text searching of the ED tracking system data for suicide, overdose, and spelling variants. Emergency department patient data were probabilistically linked to state mortality records. The principal outcome was suicide death. Suicide mortality rates were calculated by using person-year (py) analyses. Relative rates (RR) and 95% confidence intervals (95% Cls) were calculated from Cox proportional hazards models. Results: Among the 218,304 patients, the average follow-up was 6.0 years; there were 408 suicide deaths (incidence rate [IR]: 31.2 per 100,000 py). Males (IR: 48.3) had a higher rate than females (IR: 13.5; RR: 3.6; 95% CI = 2.8 to 4.6). A single ED visit for overdose (RR: 5.7; 95% CI = 4.5 to 7.4), suicidal ideation (RR: 6.7; 95% CI = 5.0 to 9.1), or self-harm (RR: 5.8; 95% CI = 5.1 to 10.6) was strongly associated with increased suicide risk, relative to other patients. Conclusions: The suicide rate among these ED patients is higher than population-based estimates. Rates among patients with suicidal ideation, overdose, or self-harm are especially high, supporting policies that mandate psychiatric interventions in all cases.