title: Evaluating risk of re-injury among 1214 army airborne soldiers using a stratified survival model.
abstract: BACKGROUND
  Many factors interact to influence an injured individual's risk of sustaining a second injury. However, the quantitative assessment of subsequent injury risk has been limited, primarily due to methodologic constraints. The purpose of this study is to present analytical methodology not previously employed in injury epidemiology to identify risk factors for subsequent injury.
  
  
  METHODS
  Data were collected from a retrospective cohort of 1214 U.S. Army Airborne soldiers. Lower extremity and low-back musculoskeletal injuries were identified from outpatient medical records. The Prentice, Williams, and Peterson (PWP) model, stratified by injury event, was used to identify risk factors for initial and subsequent injuries. A Cox proportional hazards model to the time of last injury was used to determine the magnitude of the increased risk associated with having a previous injury history.
  
  
  RESULTS
  Risk factors for initial injuries were similar to those seen in other epidemiologic studies of military populations. However, this study found that race/ethnicity, physical fitness, medical provider training, and initial injury types (traumatic versus other) were associated with subsequent injury risk. Additionally, the observed risk of injury was seven times greater among previously injured individuals.
  
  
  CONCLUSIONS
  In this population, the risk factors for injury differed by event (initial or subsequent injury), and prior injury history was a risk factor for subsequent injury. The associations between demographic characteristics, the nature of the initial injury, and risk of subsequent injury suggest that changes in the evaluation and medical management of injured individuals may decrease the risk of subsequent injury.
authors.affiliation: U.S. Army Research Institute of Environmental Medicine, Natick, MA 01760-5007, USA. garyschneid@hotmail.com
authors.forename: G A
authors.initials: GA
authors.lastname: Schneider
authors.forename: C
authors.initials: C
authors.lastname: Bigelow
authors.forename: P J
authors.initials: PJ
authors.lastname: Amoroso
mesh_terms: D000293:Adolescent; D000328:Adult; D019567:Back Injuries / Q000453:epidemiology / Q000517:prevention & control; D015984:Causality; D015331:Cohort Studies; D006801:Humans; D007869:Leg Injuries / Q000453:epidemiology / Q000517:prevention & control; D008297:Male; D008889:Military Personnel / Q000706:statistics & numerical data*; D009141:Musculoskeletal System / Q000293:injuries; D016016:Proportional Hazards Models; D012008:Recurrence; D012189:Retrospective Studies; D012306:Risk; D016019:Survival Analysis; D014947:Wounds and Injuries / Q000453:epidemiology* / Q000517:prevention & control