Study Finds Wide Variability In Survival After Emergency Treatment For Cardiac Arrest

Main Category: Cardiovascular / Cardiology
Article Date: 23 Sep 2008 - 15:00 PDT

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An analysis of emergency medical services treated cardiac arrest outcomes in 10 areas in North America finds a five-fold difference in survival rates, according to a study in the September 24 issue of JAMA.

Approximately 166,000 to 310,000 Americans per year experience an out-of-hospital cardiac arrest (OHCA), although resuscitation is not attempted in many of these cases. "Accurate estimation of the burden of OHCA is essential to evaluate progress toward improving public health by reducing cardiovascular disease," the authors write. "Knowledge of regional variation in outcomes after cardiac arrest could guide identification of effective interventions that are used in some communities but have not been implemented in others."

Graham Nichol, M.D., M.P.H., of the University of Washington, Seattle, and colleagues conducted a study to determine whether cardiac arrest incidence and outcome differed across geographic regions. The study included data on all out-of-hospital cardiac arrests in 10 North American sites (8 U.S. and 2 Canadian) from May 2006 to April 30, 2007, followed up to hospital discharge, and including data available as of June 28, 2008. Cases were assessed by organized emergency medical services (EMS) personnel. The ten sites were participants in the Resuscitation Outcomes Consortium, and were located in: Alabama; Dallas; Iowa; Milwaukee; Ottawa, Ontario; Pittsburgh; Portland, Ore.; Seattle; Toronto; and Vancouver, British Columbia.

Among the 10 sites, with a total population of 21.4 million for the areas studied, there were 20,520 cardiac arrests assessed by EMS personnel. Resuscitation was attempted in 11,898 cases (58.0 percent of total); 2,729 (22.9 percent of treated) had initial rhythm of ventricular fibrillation or ventricular tachycardia (unstable, rapid heart rhythm) or rhythms that were shockable by an automated external defibrillator; and 954 (4.6 percent) were discharged alive. The incidence of EMS-treated cardiac arrest per 100,000 population ranged from 40.3 to 86.7; for ventricular fibrillation, the incidence per 100,000 population ranged from 9.3 to 19.0. The EMS-treated cardiac arrest survival across sites ranged from 3.0 percent to 16.3 percent; ventricular fibrillation survival ranged from 7.7 percent to 39.9 percent, with significant differences across sites for incidence and survival.

"These findings have implications for prehospital emergency care. The 5-fold variation in survival after EMS-treated cardiac arrest and 5-fold variation in survival after ventricular fibrillation demonstrate that cardiac arrest is a treatable condition," the authors write.

"Out-of-hospital cardiac arrest is a common and lethal event. There are significant and important regional variations in the incidence and outcome of cardiac arrest. Additional investigation is necessary to understand the causes of this variation in an effort to better understand implications for allocation of resources to prehospital emergency care clinical practice and translational cardiac arrest research to reduce the magnitude of this variation and improve cardiovascular health."

JAMA. 2008;300[12]:1423-1431.

Editorial: Surviving Cardiac Arrest - Location, Location, Location

"… it is time to recognize the importance of EMS systems to the health of a community," writes Arthur B. Sanders, M.D., and Karl B. Kern, M.D., of the University of Arizona, Tucson, in an accompanying editorial in this week's JAMA.

"Physicians and the public should demand data on survival from cardiac arrest from every community. Publications and organizations should use these survival data when rating cities for livability and health indices, and businesses and individuals should take these public health data into account when deciding whether to relocate or expand to a new city. It is time to work to overcome barriers in each community, devote appropriate resources, and optimize survival of all patients so that location by city becomes a minor factor in survival of cardiac arrest."

JAMA. 2008;300[12]:1462-1463.

Journal of the American Medical Association (JAMA)