Risk factors for chronic exertional compartment syndrome in a physically active military population.

BACKGROUND Chronic exertional compartment syndrome (CECS) is a common source of lower extremity pain in physically active military service members. While anatomic risk factors of CECS have been proposed, there is no existing study that evaluates the correlation of demographic and occupational risk factors and the overall incidence rate of CECS in an active military population. HYPOTHESIS Young, enlisted service members in the United States (US) ground military forces would demonstrate higher incidence rates of CECS in the study population because of greater exposure to at-risk dismounted activity on the battlefield and in training. STUDY DESIGN Cohort study (prevalence); Level of evidence, 2. METHODS A retrospective study of all US active military service members with diagnosed nontraumatic exertional compartment syndrome of the lower extremity (code 729.72 in the International Classification of Diseases, 9th Edition) between 2006 and 2011 was performed using the Defense Medical Epidemiology Database. Demographic and occupational risk factors such as sex, age, race, branch of military service, and military rank were individually subcategorized, and cumulative and subgroup incidence rates of CECS were calculated using a multivariate Poisson regression model. RESULTS A total of 4100 diagnosed cases of CECS were identified within an at-risk population of 8,320,201, which correlates to an incidence rate of 0.49 cases per 1000 person-years. The annual adjusted incidence rate of CECS increased from 0.06 cases per 1000 person-years in 2006 to 0.33 cases per 1000 person-years in 2009. Increasing chronological age, female sex, white race, junior enlisted rank, and Army service were significantly correlated with an elevated risk for CECS. CONCLUSION This study systematically evaluated the epidemiology of CECS among an idealized subset at risk for this condition. Sex, age, race, military rank, and branch of service were all important factors associated with the incidence of CECS in this physically active population.