Sex modifies the association between bystander CPR and 30-day survival after out-of-hospital cardiac arrest: SOS-KANTO 2017 study.
The American journal of emergency medicine · 2026-08-03 · Registry study
Abstract
BACKGROUND: Out-of-hospital cardiac arrest (OHCA) remains a leading cause of mortality worldwide. Although bystander cardiopulmonary resuscitation (CPR) improves survival after OHCA, whether its association with survival differs according to biological sex remains uncertain. OBJECTIVE: To determine whether sex modifies the association between bystander CPR and 30-day survival following OHCA. METHODS: We conducted a multicenter prospective cohort study using the SOS-KANTO 2017 registry, including adult patients with OHCA treated at 42 emergency medical centers in Japan between September 2019 and March 2021. The primary exposure was bystander CPR, and the primary outcome was 30-day survival. Multivariable Cox proportional hazards models were constructed separately for men and women after adjustment for clinically relevant covariates. A formal interaction analysis was performed to evaluate whether the association between bystander CPR and survival differed by sex. Sensitivity analyses excluding targeted temperature management from the adjustment model and exploratory analyses of favorable neurological outcome (Cerebral Performance Category [CPC] 1-2) were also conducted. RESULTS: Among 9081 eligible patients, 5622 (61.9%) were men and 3459 (38.1%) were women. Crude 30-day survival was higher among patients receiving bystander CPR in both men (11.0% vs. 4.5%) and women (5.4% vs. 3.4%). After multivariable adjustment, bystander CPR remained independently associated with 30-day survival in men (adjusted hazard ratio [aHR], 1.54; 95% confidence interval [CI], 1.23-1.92) but not in women (aHR, 1.33; 95% CI, 0.93-1.91). Formal interaction analysis demonstrated significant effect modification by sex (interaction P < 0.001). Sensitivity analyses excluding targeted temperature management yielded similar results. Exploratory analyses demonstrated higher crude rates of favorable neurological outcome among patients receiving bystander CPR in both sexes. CONCLUSIONS: Bystander CPR was associated with improved 30-day survival after OHCA in both sexes; however, the magnitude of this association differed by sex. Formal interaction and sensitivity analyses support biological sex as a potential effect modifier of the association between bystander CPR and survival. Further investigation into the biological and clinical mechanisms underlying these differences may help optimize resuscitation strategies while ensuring equitable delivery of bystander CPR.
Tags
Bystanders & volunteers · Mortality & survival · Sex & gender