Sept. 25, 2008
Survival varies widely after emergency treatment for cardiac arrest
An analysis of cardiac arrest outcomes for people treated initially out-of-hospital by emergency medical services (EMS) in 10 areas in North America finds a five-fold range of difference in survival rates. Iowa, one of the study areas, compared favorably in "survival to discharge," with 11 percent of patients treated by EMS in out-of-hospital situations surviving through hospital discharge, compared to the study average of 7.9 percent.
However, in terms of the use of EMS treatment for out-of-hospital cardiac arrest, people in Iowa were slightly less likely to receive such care -- 51.3 per 100,000 of Iowa's population compared to 56 per 100,000 in the study population overall.
The findings appear in the Sept. 24 issue of the Journal of the American Medical Association. Graham Nichol, M.D., at the University of Washington, Seattle, and colleagues conducted the study to see whether cardiac arrest incidence and outcome differed across geographic regions.
"While Iowa compared favorably in terms of overall outcomes related to cardiac arrest survival from EMS-treatment through hospital discharge, our state had a lower than overall incidence in EMS treatment for out-of-hospital cardiac arrest," said Dianne Atkins, M.D., professor of pediatrics at the UI Roy J. and Lucille A. Carver College of Medicine, who helped provide information about Iowa for the study.
"This difference may be related to the rural nature of our state, but should be studied in more depth," added Atkins, a pediatric cardiologist with UI Children's Hospital and the UI Heart and Vascular Center.
Each year, 166,000 to 310,000 Americans have out-of-hospital cardiac arrest, although resuscitation is not attempted in many cases. The study concludes that information about regional variation in outcomes after cardiac arrest could help identify effective interventions that are used in some communities but not in others.
The study included data on all out-of-hospital cardiac arrests in 10 North American sites from May 2006 through April 2007, followed up to hospital discharge, and including data available as of June 28, 2008.
Cases were assessed by organized emergency medical services personnel. The 10 sites were part of the Resuscitation Outcomes Consortium, and in addition to Iowa, included Alabama; Dallas; Milwaukee; Ottawa; Pittsburgh; Portland, Ore.; Seattle; Toronto; and Vancouver.
The areas studied had a combined population of 21.4 million and included 20,520 cardiac arrests assessed by EMS personnel. Resuscitation was attempted in 11,898 cases (58 percent of total), and 2,729 individuals (13.3 percent of total) had initial rhythm of ventricular fibrillation or ventricular tachycardia (unstable, rapid heart rhythm) or rhythms that were shockable by an automated external defibrillator. From all 20,520 cases initially assessed by EMS personnel, 954 people, or 4.6 percent, were discharged alive.
The incidence of EMS-treated cardiac arrest per 100,000 population ranged from 40.3 to 86.7. The EMS-treated cardiac arrest survival across sites ranged from 3 percent to 16.3 percent. For ventricular fibrillation, the incidence of EMS-treated cardiac arrest per 100,000 population ranged from 9.3 to 19, and ventricular fibrillation survival ranged significantly from 7.7 percent to 39.9 percent.
"The findings show that out-of-hospital cardiac arrest is a treatable condition. The results also support the need to require that out-of-hospital cardiac arrest be a reportable event to public health groups, similar to infectious diseases, so that each community can monitor and improve outcomes after cardiac arrest," Atkins said.
The study team said that more investigation is needed to understand the underlying causes for differences among regions. Such information would have implications for allocating resources to pre-hospital emergency care practice, as well as to translational cardiac arrest research.
An accompanying editorial, written by Arthur B. Sanders, M.D., and Karl B. Kern, M.D., at the University of Arizona, Tucson, also noted that the wide variability in cardiac arrest incidence and outcomes emphasizes the need for individual communities and states to each "know its numbers."
Atkins said that the Iowa EMS Patient Registry, maintained by the Iowa Bureau of EMS, an agency of the Iowa Department of Public Health, is a resource for EMS agencies to understand and compare their statistics. "The need for increased research, supported at both the state and local levels, is emphasized by the collection and analysis of this data," Atkins said.
The study was supported by a cooperative agreement with the National Heart, Lung, and Blood Institute in partnership with the National Institute of Neurological Disorders and Stroke, the Canadian Institutes of Health Research Institute of Circulatory and Respiratory Health, Defence Research and Development Canada, the American Heart Association, and the Heart and Stroke Foundation of Canada.
NOTE TO EDITORS: This release includes information provided by the Journal of the American Medical Association.
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