Effect of Bystander CPR on Survival After Out-of-Hospital Cardiac Arrest: A Systematic Review and Meta-Analysis

BACKGROUND: Out-of-hospital cardiac arrest (OHCA) is a leading cause of death globally. The timely initiation of bystander cardiopulmonary resuscitation (CPR) is considered a critical determinant of survival. OBJECTIVE: To evaluate the association of bystander CPR with survival after OHCA. METHODS: We conducted a systematic review and meta-analysis, searching PubMed, EMBASE, Web of Science, and Scopus through July 31, 2025. We included observational studies that compared survival outcomes between OHCA patients who received bystander CPR and those who did not. The primary outcomes assessed were survival to hospital admission, survival to hospital discharge, and 30-day survival. A random-effects model was used to pool adjusted odds ratios (ORs). Potential sources of heterogeneity were examined using subgroup analyses and meta-regressions. Risk of bias was evaluated using Risk Of Bias In Nonrandomized Studies of Interventions. RESULTS: Our analysis included 72 studies, comprising 2,914,595 OHCA events. The pooled analysis showed a 26% increase in odds of survival to hospital admission [12 studies; OR, 1.26; 95% confidence interval (CI), 1.09-1.46; I 2 = 77.9%]. The benefit was more pronounced for survival to hospital discharge, with a 44% increase in odds (43 studies; OR, 1.44; 95% CI, 1.33-1.56; I 2 = 83.8%), and was greatest for 30-day survival, with a 50% increase in odds (23 studies; OR, 1.50; 95% CI, 1.34-1.67; I 2 = 95.6%). The survival benefit varied significantly by continent. Meta-regression analyses showed the benefit was attenuated in studies with higher mean patient age and a higher proportion of female patients. The certainty of evidence was moderate. CONCLUSIONS: Bystander-initiated CPR is consistently associated with a significant improvement in survival after OHCA. These findings provide a strong evidence base to justify strategic investment in public first aid and CPR training policies to improve OHCA outcomes.