Effect Of Emergency Medical Service Response Time On Survival And Neurological Outcomes In Out-Of-Hospital Cardiac Arrest: A Systematic Review

Abstract

Background:
Out-of-hospital cardiac arrest (OHCA) remains a leading cause of mortality worldwide, with survival and neurological outcomes highly dependent on timely intervention. Emergency medical service (EMS) response time is a critical determinant within the chain of survival.

Objective:
This systematic review aimed to evaluate the effect of EMS response time on survival and neurological outcomes among OHCA patients.

Methods:
A systematic review was conducted in accordance with PRISMA 2020 guidelines. Electronic databases including PubMed, Scopus, Web of Science, Embase, and Google Scholar were searched for studies published between 2010 and 2025. Observational studies examining EMS response time and OHCA outcomes were included. Eleven studies met the inclusion criteria. Data were extracted and synthesized using a narrative approach due to heterogeneity in study designs and outcome measures.

Results:
Across the included studies, shorter EMS response times were consistently associated with improved outcomes. Each one-minute delay in response time was associated with a 4% to 7% reduction in survival and a significant decline in neurological recovery. Optimal response time thresholds were commonly identified between 6 and 8 minutes. Studies also highlighted the modifying effect of bystander cardiopulmonary resuscitation (CPR), which extended the effective response window and improved survival rates. Variability in outcomes across EMS systems emphasized the role of operational efficiency and system-level factors.

Conclusion:
Rapid EMS response is a critical determinant of survival and neurological outcomes in OHCA. Efforts to reduce response times and strengthen early intervention strategies are essential to improve patient outcomes.