Public assistance and suicide-related cardiac arrest in emergency departments: a nationwide registry-based study in Japan

BACKGROUND: Individuals receiving public assistance have been reported to be at increased suicide risk; however, evidence from emergency medical settings remains limited. This study investigated the population-level association between public assistance status and suicide-related cardiac arrest using events captured through emergency department presentations. METHODS: We conducted a nationwide registry-based study using the Japan Registry of Self-harm and Suicide Attempts, including patients presenting to emergency and critical care centers following self-harm or suicide attempts from December 2022 to December 2023. The primary outcome was suicide-related cardiac arrest, and non-fatal self-harm was examined as a related outcome. Adjusted incidence rate ratios (aIRRs) were estimated using Poisson regression models with the log of the population at risk included as an offset, adjusting for age and sex. National suicide statistics were analyzed for validation. RESULTS: Among 1,757 patients, 207 (11.8%) were receiving public assistance. Public assistance status was associated with a higher incidence of suicide-related cardiac arrest compared with non-recipients (aIRR 3.34, 95% confidence interval [CI], 1.60-6.95). A strong association was also observed with non-fatal self-harm (aIRR 13.10, 95% CI, 8.25-20.80). Similar associations were observed across sex and age groups. Analyses using national suicide statistics confirmed a consistent association (aIRR 2.21, 95% CI, 1.50-3.26). CONCLUSIONS: In this nationwide registry-based study using events captured through emergency department presentations, public assistance status was associated with suicide-related cardiac arrest and non-fatal self-harm. At the population level, public assistance recipients showed a higher incidence of suicide-related cardiac arrest, supporting the public health relevance of this socioeconomic indicator.