Evaluating Variation in Return of Spontaneous Circulation Rates Across EMS Agencies in Michigan

Background: Out-of-hospital cardiac arrest (OHCA) outcomes vary significantly across U.S. communities; however, systems of care factors that increase the likelihood of survival have not been well elucidated. The Enhancing Pre-Hospital Outcomes for Cardiac Arrest (EPOC) study is quantifying variation in the rate of sustained return of spontaneous circulation (ROSC) upon ED arrival across Michigan EMS agencies as a first step to identifying ‘best practices’ in prehospital OHCA care. Methods: Michigan Cardiac Arrest Registry to Enhance Survival (CARES) data for the years 2014-2016 was used. EMS agencies with 5+ arrests over the study years were included in the analysis. Using mixed-effects logistic regression, we calculated each agency’s reliability-adjusted sustained ROSC upon ED arrival; these rates were standardized across patient-, community-, and arrest-level characteristics. Results: A total of 91 agencies covering >6.8 million lives met inclusion criteria. We included 14,219 OHCA patients with a mean age of 62.6, 40.0% female, and 18.2% with a shockable rhythm in the analyses. Across all agencies, the mean patient-standardized rate of sustained ROSC with pulse upon ED arrival was 25.3% (range, 6.1%-51.9%; IQR range, 18.9%-31.2%) ( Figure 1 ). There were 14 agencies with patient-standardized rates and 95% CIs that exceeded the overall mean survival rate suggesting better-than-average outcomes while 16 agencies had rates and 95% CIs that were lower than the overall mean survival rate. Conclusion: We found more than 8-fold variation in OHCA survival rates across EMS agencies in Michigan, suggesting large differences in the effectiveness of prehospital systems of care. Future qualitative work will seek to identify ‘best practices’ by further determining the role of key factors such as tele-dispatch CPR, EMS agencies, fire, and police within high performing systems.