What is the variation in survival after out-of-hospital cardiac arrest between emergency medical services (EMS) agencies?
In this cohort study, among 43 656 adults treated for out-of-hospital cardiac arrest by any of 112 EMS agencies, there was a median difference of 56% in the odds of survival to hospital discharge for similar participants between any 2 randomly selected EMS agencies, after adjusting for known measured sources of variability and clustering of patients within agencies.
This study suggests there is substantial unexplained variation in survival after out-of-hospital cardiac arrest across treating EMS agencies in North America, despite controlling for documented patient and agency characteristics.
Emergency medical services (EMS) deliver essential initial care for patients with out-of-hospital cardiac arrest (OHCA), but the extent to which patient outcomes vary between different EMS agencies is not fully understood.
To quantify variation in patient outcomes after OHCA across EMS agencies.
Design, Setting, and Participants
This observational cohort study was conducted in the Resuscitation Outcomes Consortium (ROC) Epistry, a prospective multicenter OHCA registry at 10 sites in North America. Any adult with OHCA treated by an EMS from April 2011 through June 2015 was included. Data analysis occurred from May 2017 to March 2018.
Treating EMS agency.
Main Outcomes and Measures
The primary outcome was survival to hospital discharge. Secondary outcomes were return of spontaneous circulation at emergency department arrival and favorable functional outcome at hospital discharge (defined as a modified Rankin scale score ≤3). Multivariable hierarchical logistic regression models were used to adjust confounders and clustering of patients within EMS agencies, and calculated median odds ratios (MORs) were used to quantify the extent of residual variation in outcomes between EMS agencies.
We identified 43 656 patients with OHCA treated by 112 EMS agencies. At EMS agency level, we observed large variations in survival to hospital discharge (range, 0%-28.9%; unadjusted MOR, 1.43 [95% CI, 1.34-1.54]), return of spontaneous circulation on emergency department arrival (range, 9.0%-57.1%; unadjusted MOR, 1.53 [95% CI, 1.43-1.65]), and favorable functional outcome (range, 0%-20.4%; unadjusted MOR, 1.54 [95% CI, 1.40-1.73]). This variation persisted despite adjustment for patient-level and EMS agency–level factors known to be associated with outcomes (adjusted MOR for survival 1.56 [95% CI 1.44-1.73]; adjusted MOR for return of spontaneous circulation at emergency department arrival, 1.50 [95% CI, 1.41-1.62]; adjusted MOR for functionally favorable survival, 1.53 [95% CI, 1.37-1.78]). After restricting analysis to those who survived more than 60 minutes after hospital arrival and including hospital treatment characteristics, the variation persisted (adjusted MOR for survival, 1.49 [95% CI, 1.36-1.69]; adjusted MOR for functionally favorable survival, 1.34 [95% CI, 1.20-1.59]).
Conclusions and Relevance
We found substantial variations in patient outcomes after OHCA between a large group of EMS agencies in North America that were not explained by documented patient-level and EMS agency–level variables.
Okubo M, Schmicker RH, Wallace DJ, et al. Variation in Survival After Out-of-Hospital Cardiac Arrest Between Emergency Medical Services Agencies. JAMA Cardiol. 2018;3(10):989–999. doi:10.1001/jamacardio.2018.3037
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