Regional disparities in 1-month survival following traffic accident-related out-of-hospital cardiac arrest in Japan: A nationwide observational study

Aim : To clarify regional disparities in 1-month survival after traffic accident-related out-of-hospital cardiac arrest (OHCA) in Japan and examine associations with emergency medical services (EMS) and healthcare indicators. Methods : We conducted a retrospective study of 9,525 traffic accident-related OHCAs using national EMS data from 2018–2022. Prefectures were grouped by 1-month survival rates. Multivariable logistic regression and partial correlation analyses assessed factors related to patient characteristics, EMS, and medical resources. Results : In low-survival regions, rates of advanced airway management (37.7%) and epinephrine administration (29.8%) were significantly higher (p < 0.001). Conversely, the proportion of patients transported to level-3 hospitals was significantly higher in high-survival regions (p < 0.001). Logistic regression revealed that advanced airway management (OR: 1.37; 95% CI: 1.22–1.54; p < 0.001), epinephrine administration (OR: 1.43; 95% CI: 1.26–1.62; p < 0.001), and traffic accidents as the direct cause of cardiac arrest (OR: 1.17; 95% CI: 1.04–1.30; p = 0.006) were significantly associated with lower-survival regions. In contrast, witnessed arrests (OR: 0.82; 95% CI: 0.73–0.92; p = 0.001), BCPR (OR: 0.85; 95% CI: 0.75–0.96; p = 0.012), and transport to level-3 hospitals (OR: 0.71; 95% CI: 0.64–0.80; p < 0.001) were negatively associated with classification into low-survival regions. Partial correlation analysis showed positive associations between survival and the number of level-3 hospitals (r = 0.45) and physicians (r = 0.36, p = 0.08) per 100,000 population. Conclusion : Survival outcomes following traffic accident-related cardiac arrest varied across regions, and distribution of medical resources appeared to influence these disparities.