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International validation of the out-of-hospital cardiac arrest score in the United States*

Hunziker, Sabina MD; Bivens, Matthew J. MD; Cocchi, Michael N. MD; Miller, Joseph MD; Salciccioli, Justin; Howell, Michael D. MD; Donnino, Michael W. MD

Critical Care Medicine:
doi: 10.1097/CCM.0b013e318218a05b
Clinical Investigations
Abstract

Objective: Investigators in France have developed a risk score to predict death or poor neurologic outcome after out-of-hospital cardiac arrest. The aim of this study is to externally validate this score in an independent patient population in the United States.

Design: Retrospective, observational, cohort study.

Patients: Patients being admitted to the intensive care unit after out-of-hospital cardiac arrest.

Setting: Two geographically distinct tertiary care hospitals in the United States.

Interventions: None.

Measurements and Main Results: The primary end point was poor outcome, defined as either death or a Cerebral Performance Category score of 3–5. The secondary end point was all-cause mortality. Calibration was assessed by comparing the number of expected outcomes based on the logistic model of the French study with observed outcomes within this study using Hosmer-Lemeshow C test (goodness-of-fit). Discrimination was assessed by calculation of the area under the receiver operating characteristic curve. Of a total of 128 patients, 99 (77%) had a poor outcome, including 91 nonsurvivors (71%). The probability of poor neurologic outcome and mortality increased stepwise with increasing out-of-hospital cardiac arrest score. Graphic display of observed against predicted outcomes and goodness-of-fit test indicated good calibration of the score (p = .4). The score showed good discrimination for poor outcome (area under the receiving operating characteristic curve, 0.85; 95% confidence interval, 0.79–0.92) and for mortality (area under the receiving operating characteristic curve, 0.85; 95% confidence interval, 0.78–0.91). In patients with an out-of-hospital cardiac arrest score >40 points and >60 points, the positive predictive value for poor outcome was 97% and 100%, respectively.

Conclusions: This study found good calibration and high discrimination of the out-of-hospital cardiac arrest score in two geographically distinct patient populations in the United States. Particularly, this score had a high positive predictive value and performed well in identifying high-risk patients for poor outcomes.

Author Information

From the Department of Medicine, Division of Pulmonary, Critical Care, and Sleep Medicine (SH, MNC, MDH, MWD), the Silverman Institute for Healthcare Quality and Safety (SH, MDH), and the Department of Emergency Medicine (MJB, MNC, JS, MWD); Beth Israel Deaconess Medical Center, Boston, MA; and the Department of Emergency Medicine (JM), Henry Ford Hospital, Detroit, MI.

This project was funded, in part, from American Heart Association grant 0735533T. S.H. was support partly by an unrestricted research grant from the Swiss National Foundation (SNF PBBSP3-128266) and partly from the University of Basel, Basel, Switzerland.

Dr. Cocchi has a grant from the American Heart Association to develop a severity of illness score in postcardiac arrest patients. Dr. Howell is partly supported by a grant from the Robert Wood Johnson Foundation's Physician Faculty Scholars Program (66350). Dr. Donnino has a grant from the American Heart Association for corticosteroids in postcardiac arrest shock. The remaining authors have not disclosed any potential conflicts of interest.

Drs. Bivens, Cocchi, and Donnino conceived and designed the study and wrote the study protocol. Dr. Bivens, Dr. Cocchi, Dr. Miller, and Mr. Salciccioli collected data. The statistical analyses and the first draft of manuscript were performed by Drs. Hunziker and Howell. All authors amended and commented on the manuscript and approved the final version.

For information regarding this article, E-mail: MDonnino@bidmc.harvard.edu

© 2011 by the Society of Critical Care Medicine and Lippincott Williams & Wilkins