Statistical Methodology

IX. Survival Analysis

Authors

  • Kelly D. Young MD,

    Corresponding author
    1. Departments of Emergency Medicine and Pediatrics, Harbor-UCLA Medical Center, UCLA School of Medicine, Torrance, CA; Center for Emergency Medicine of Western Pennsylvania
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  • James J. Menegazzi PhD,

    1. Department of Emergency Medicine and School of Medicine, University of Pittsburgh, Pittsburgh, PA
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  • Roger J. Lewis MD, PhD

    1. Departments of Emergency Medicine and Pediatrics, Harbor-UCLA Medical Center, UCLA School of Medicine, Torrance, CA; Center for Emergency Medicine of Western Pennsylvania
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Department of Emergency Medicine, Harbor-UCLA Medical Center, 1000 West Carson Street, Box 21, Torrance, CA 90509. Fax: 310-212-6101; e-mail:kyoung@emedharbor.edu

Abstract

Survival analysis is a group of statistical methods used to analyze data representing the time to an event of interest, e.g., the duration of survival after an out-of-hospital cardiac arrest or the length of time a patient stays in the ED. Survival analysis properly accounts for patients who are lost to follow-up and for patients who have not yet experienced the event of interest at the end of the study's observation period (censored data). This article acquaints the reader with the terminology, methodology, and limitations of survival analysis. Specific methods discussed include life tables, the Kaplan-Meier product limit estimate, the log-rank test, and the multivariate Cox proportional hazards model.

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