Prehospital factors associated with return of spontaneous circulation after nonshockable out-of-hospital cardiac arrest: a retrospective analysis of the Polk County Fire Rescue CARES registry.

Among 1,198 included patients, median age was 66 years (interquartile range [IQR], 53-78), 59.8% were male, 20.9% had pulseless electrical activity, and 79.1% had asystole.

Any ROSC occurred in 166 patients (13.9%), and 146 (12.2%) had sustained ROSC.

In complete-case models (n=893), witnessed arrest, pulseless electrical activity rather than asystole, field hypothermia care, and female sex were associated with both outcomes.

Shorter time to first CPR was additionally associated with sustained ROSC (aOR per minute, 0.989; 95% CI, 0.979-0.999).