JAMA: Wide variability in survival after emergency treatment for cardiac arrest

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Emergency medical services (EMS) and emergency room (ER)–treated cardiac arrest outcomes in 10 areas in North America finds a five-fold difference in survival rates, according to a study in the Sept. 24 issue of Journal American Medical Association.

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 the cases.

“Accurate estimation of the burden of OHCA is essential to evaluate progress toward improving public health by reducing cardiovascular disease,” according to the authors. “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, MD, of the University of Washington in 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 (eight U.S. and two Canadian) from May 2006 to April 30, 2007, followed up to hospital discharge, and including data available as of June 28, according the researchers. Investigators assessed cases by organized EMS personnel.

Among the 10 sites, with a total population of 21.4 million for the areas studied, the EMS personnel assessed 20,520 cardiac arrests. Resuscitation was attempted in 11,898 cases (58 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.

According to researchers, 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. The EMS-treated cardiac arrest survival across sites ranged from 3 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 pre-hospital 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 wrote.

“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 pre-hospital emergency care clinical practice and translational cardiac arrest research to reduce the magnitude of this variation and improve cardiovascular health,” Nichol and colleagues concluded.

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.