Age and Overdose at the Index Attempt Predict Suicide Reattempts After Emergency Admission: A Multicenter Cohort Study.

aimA history of suicide attempts is a well-established predictor of future suicidal behavior; however, longitudinal evidence from real-world emergency settings remains limited. Because age and self-poisoning/overdose are readily available at emergency presentation and may inform post-discharge care, we examined whether age and overdose at the index suicide attempt predict medically attended suicide reattempts after emergency admission.

methodsWe conducted a multicenter retrospective cohort study of 1038 patients admitted to emergency departments after suicide attempts between 2020 and 2025 at three tertiary hospitals in Japan (Dokkyo Medical University Hospital, Jichi Medical University Hospital, and Hachinohe City Hospital). Patients were followed longitudinally to identify suicide reattempts requiring medical attention. Time-to-event analyses were performed using Kaplan-Meier methods and Cox proportional hazards models. Age (< 40 vs. ≥ 40 years) and sex were included as baseline covariates, and overdose at the index attempt was examined as an explanatory variable. Sensitivity analyses were performed using a stricter definition of overdose (overdose alone).

resultsDuring follow-up, 58 medically attended suicide reattempts were identified. Kaplan-Meier analyses showed higher cumulative reattempt risk in females and in patients aged 39 years or younger. In Cox proportional hazards models, age ≥ 40 years was associated with a lower risk of suicide reattempt, whereas overdose at the index attempt was associated with a significantly increased risk of suicide reattempt. These findings were consistent in sensitivity analyses.

conclusionYounger age and overdose at the index suicide attempt were independently associated with an increased risk of medically attended suicide reattempt. Assessment of the initial suicide method may help identify patients requiring intensive post-discharge monitoring.