Correlation between EMS Agency Rates of Survival to Hospital Admission and Hospital Survival Outcomes for Cardiac Arrest

Abstract

Background: Survival to hospital admission for out-of-hospital cardiac arrest (OHCA) is an important resuscitation outcome to gauge emergency medical service (EMS) agency performance. However, its correlation with EMS rates of survival to hospital discharge and favorable neurological survival is unclear. Methods: Using the Cardiac Arrest Registry to Enhance Survival (CARES), we identified adults with non-traumatic OHCAs during 2 periods: 2015–2019 (before the COVID-19 pandemic) and 2022–2024 (after the peak pandemic years). Multivariable hierarchical logistic regression was used to derive EMS agency-level risk-standardized survival rates (RSSRs) for hospital admission, hospital discharge, and favorable neurological survival during each period. We then assessed the correlation between EMS agency rates of survival to admission vs. discharge and favorable neurological survival using weighted linear regression, and whether the correlations differed by neighborhood income (above vs. below median household income) and race/ethnicity (categorized as predominantly White [>80% of residents], majority Black/Hispanic [>50% of residents], or integrated). Results: A total of 544,296 events from 1,838 EMS agencies met inclusion criteria (252,137 pre-COVID; 292,159 post-COVID). During 2015–2019, EMS rates of survival to admission were strongly correlated with survival to discharge (weighted r=0.68 [95% CI: 0.64–0.72]) and favorable neurological survival (weighted r=0.54 (95% CI: 0.43–0.59]). These correlations were similar during 2022–2024 (weighted r=0.63 (95% CI: 0.59–0.66]) and weighted r=0.48 (95% CI: 0.44–0.53]), respectively). Neighborhood racial-ethnic composition modified the correlation between EMS rates of survival to admission and survival outcomes at discharge in both periods (all interactions <0.05), but the correlations remained strong in each neighborhood group. Similar findings were found for the interactions by neighborhood income strata. Conclusions: EMS agency rates of survival to hospital admission are strongly correlated with their rates of survival to hospital discharge and favorable neurological survival. These findings support the use of survival to hospital admission as a performance metric for EMS systems.