Effect of Transport Interval on Out-of-Hospital Cardiac Arrest Survival in the OPALS Study: Implications for Triaging Patients to Specialized Cardiac Arrest Centers
Study objective
To identify any association between out-of-hospital transport interval and survival to hospital discharge in victims of out-of-hospital cardiac arrest.
Methods
Data from the Ontario Prehospital Advanced Life Support Study (January 1, 1991, to December 31, 2002), an Utstein-compliant registry of out-of-hospital cardiac arrest patients from 21 communities, were analyzed. Logistic regression identified factors that were independently associated with survival in consecutive adult, nontraumatic, out-of-hospital cardiac arrest patients and in the subgroup with return of spontaneous circulation.
Results
A total of 18,987 patients met criteria and 15,559 (81.9%) had complete data for analysis (study group). Return of spontaneous circulation was achieved in 2,299 patients (14.8%), and 689 (4.4%) survived to hospital discharge. Median transport interval was 4.0 minutes (25th quartile 3.0 minutes; 75th quartile 6.2 minutes) for survivors and 4.2 minutes (25th quartile 3.0, 75th quartile 6.2) for nonsurvivors. Logistic regression revealed multiple factors that were independently associated with survival: witnessed arrest (odds ratio 2.61; 95% confidence interval [CI] 2.05 to 3.34), bystander cardiopulmonary resuscitation (odds ratio 2.22; 95% CI 1.82 to 2.70), initial rhythm of ventricular fibrillation/tachycardia (odds ratio 2.22; 95% CI 1.97 to 2.50), and shorter emergency medical services (EMS) response interval (odds ratio 1.26; 95% CI 1.20 to 1.33). There was no association between transport interval and survival in either the study group (odds ratio 1.01; 95% CI 0.99 to 1.05) or the return of spontaneous circulation subgroup (odds ratio 1.04; 95% CI 0.99, 1.08).
Conclusion
In a large out-of-hospital cardiac arrest study from demographically diverse EMS systems, longer transport interval was not associated with decreased survival. Given the growing evidence showing major influence from specialized postarrest care, these findings support conducting clinical trials that assess the effectiveness and safety of bypassing local hospitals to take patients to regional cardiac arrest centers.
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Supervising editor: Donald M. Yealy, MD.
Author contributions: DWS, IGS, JM, JD, and GAW conceived the OPALS study, designed the original trial, obtained research funding, and supervised the conduct of the trial and data collection. All authors made substantial contributions to the conception and design of this secondary analysis and analyzed the meaning, conclusions, and limitations of the results. MDB and GAW provided statistical advice, and MDB analyzed the data and served as the statistical consultant. DWS drafted the article, and all authors contributed substantially to its revision. DWS takes responsibility for the paper as a whole.
Funding and support: By Annals policy, all authors are required to disclose any and all commercial, financial, and other relationships in any way related to the subject of this article that might create any potential conflict of interest. See the Manuscript Submission Agreement in this issue for examples of specific conflicts covered by this statement. Funded by Ontario Ministry of Health and Canadian Health Services Research Foundation.
Publication date: Available online January 23, 2009.
Reprints not available from the authors.
PII: S0196-0644(08)02060-X
doi:10.1016/j.annemergmed.2008.11.020
© 2008 American College of Emergency Physicians. Published by Elsevier Inc. All rights reserved.
Refers to article:
- Transport of Patients After Out-of-Hospital Cardiac Arrest: Closest Facility or Most Appropriate Facility? , 23 March 2009
