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Observational Study
. 2018 Oct 1;3(10):989-999.
doi: 10.1001/jamacardio.2018.3037.

Variation in Survival After Out-of-Hospital Cardiac Arrest Between Emergency Medical Services Agencies

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Free PMC article
Observational Study

Variation in Survival After Out-of-Hospital Cardiac Arrest Between Emergency Medical Services Agencies

Masashi Okubo et al. JAMA Cardiol. .
Free PMC article

Abstract

Importance: 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.

Objective: 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.

Exposure: 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.

Results: 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.

Conflict of interest statement

Conflict of Interest Disclosures: All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Mr Schmicker reported receiving grants from National Heart, Lung, and Blood Institute, during the conduct of the study. Dr Idris reported receiving grants from the National Heart, Lung, and Blood Institute during the conduct of the study. Dr Morrison reported receiving salary support from the National Institutes of Health during the Resuscitation Outcomes Consortium (ROC) funding period, receiving ROC funding from the Heart and Stroke Foundation of Canada and the Canadian Institute of Health Research, and having peer-reviewed research project grant support from the Canadian Institute of Health Research. Dr Kurz reported receiving grants from the National Institutes of Health, Society of Critical Care Medicine, Emergency Medicine Foundation, the American Heart Association, and the University of Alabama General Endowment Fund, grants and personal fees from Zoll Medical Corp, and other support from Rapid Oxygen Company outside the submitted work. Dr Cheskes reported receiving personal fees from Zoll Medical Corporation and Physio Control Corporation outside the submitted work. Dr Kudenchuk reported receiving grants from National Heart, Lung, and Blood Institute during the conduct of the study. Ms Zive reported salary support from grants from the National Heart, Lung, and Blood Institute during the conduct of the study. Dr Aufderheide reported receiving grants from the National Heart, Lung, and Blood Institute during the conduct of the study. Ms Herren reported receiving grants from the National Heart, Lung, and Blood Institute to the Resuscitation Outcomes Consortium during the conduct of the study. Dr Vaillancourt reported receiving grants from the Canadian Institute of Health Research and the Heart and Stroke Foundation of Canada during the conduct of the study. Dr Elmer reported receiving grants from the National Institute of Neurological Disorders and Stroke during the conduct of the study. Dr Callaway reported receiving grants from the National Heart, Lung, and Blood Institute during the conduct of the study. Per Dr Morrison, the contributing emergency medical services (paramedic and fire) in Toronto Regional RescuNET received in-kind support from defibrillator industrial partners (ZOLL and Medtronic-Physio Control) during the ROC funding period. No other disclosures were reported.

Figures

Figure 1.
Figure 1.. Patient Flow
DNR indicates do not resuscitate [orders]; EMS, emergency medical services; OHCA, out-of-hospital cardiac arrest; ROC, Resuscitation Outcome Consortium.
Figure 2.
Figure 2.. Outcome Variations Between Emergency Medical Services (EMS) Agencies
A, Variations in rate of survival to hospital discharge; B, favorable functional outcome at hospital discharge; and C, return of spontaneous circulation at emergency department arrival.

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