Timing of Public-Access Defibrillation for Patients With Out-of-Hospital Cardiac Arrest: A Nationwide Cohort Study Using Time-Dependent Propensity Score Sequential Matching Approach.

Summary

In a nationwide prospective Japanese registry, 1,664 matched pairs of bystander-witnessed ventricular fibrillation cardiac arrests in public locations were analyzed using minute-by-minute time-dependent propensity score matching. Public-access defibrillation before emergency medical services arrival was associated with a 46% higher relative probability of 1-month survival with favorable neurological outcome. The association remained directionally favorable across defibrillation timing categories, although estimates were imprecise after 15 minutes.

Key Findings

• After time-dependent sequential matching, 1,664 matched pairs of bystander-witnessed ventricular fibrillation arrests were identified.
• Public-access defibrillation was associated with a corrected relative risk of 1.46 for 1-month survival with favorable neurological outcome.
• Effect estimates remained directionally favorable for defibrillation within 0–4, 5–9, and 10–14 minutes, with wider uncertainty after 15 minutes.

Clinical Implications

The findings support continued deployment of automated external defibrillators in public locations, improved public training, and systems that minimize the interval between collapse recognition and defibrillation. Emergency response policies should prioritize rapid bystander intervention before emergency medical services arrival.

Limitations

• The observational design cannot eliminate residual confounding, including differences in location, witness characteristics, and CPR quality.
• The analysis was restricted to bystander-witnessed ventricular fibrillation arrests in public locations, limiting generalizability to other arrest rhythms and settings.

Future Directions

Future research should evaluate integrated community response systems, including dispatcher-assisted CPR, smartphone-based responder activation, automated external defibrillator drones, and the effectiveness of public-access defibrillation in nonpublic settings and nonshockable rhythms.