Does out-of-hospital cardiac arrest survival differ by EMS agency type in the U.S.? Insights from the CARES registry.

Background: There are limited data on whether out-of-hospital cardiac arrest (OHCA) survival differs by emergency medical service (EMS) agency type in the U.S. Methods: Within the Cardiac Arrest Registry to Enhance Survival, we surveyed participating EMS agencies with ≥20 OHCA annually during 2015-2019. Agencies were categorized as fire-based, private, government-based, or other (including hospital-based). Using hierarchical logistic regression, we computed the risk-standardized survival rate (RSSR) to hospital admission and discharge for each EMS agency and examined for differences in RSSR across agency types. Results: Of 577 eligible EMS agencies, 470 (81.5 %) completed the survey. Overall, 40.0 % of agencies were fire-based, 35.0 % were private, 17.3 % were government-based, and 7.7 % were other. Mean agency-level RSSR to hospital admission was 27.8 % ± 3.6 % and was highest in fire-based EMS agencies (28.9 %) and lowest in agencies that were private or other (26.8 %; P < 0.001 for comparison across all groups). Mean agency-level RSSR to hospital discharge was 10.1 % ± 1.8 % and was highest in fire-based agencies (10.3 %) and lowest in agencies that were private or other (9.7 %; P < 0.003 across all groups). Fire-based agencies were more likely to have higher numbers of paramedics, lower annual number of dispatches per paramedic, more hours of OHCA training during orientation, and shorter arrival times on the scene and transport times to the hospital. Conclusions: In the U.S., OHCAs attended by fire-based agencies were associated with modestly higher rates of survival to hospital admission compared to OHCAs attended by other EMS agency types. Several resuscitation practices differed by EMS agency type.