The Influence of Musculoskeletal Conditions, Behavioral Health Diagnoses, and Demographic Factors on Injury-Related Outcome in a High-Demand Population

Background The extent to which musculoskeletal injuries and sociodemographic factors impact long-term outcome remains unknown. The purpose of this study was to provide a prognostic analysis of the influence of musculoskeletal conditions, behavioral health diagnoses, and patient-based characteristics on outcomes among a longitudinal cohort. Methods This is a longitudinal observational study of the population of an Army brigade deployed to Iraq from 2006 to 2007. The 4087 soldiers who survived the deployment were followed for forty-eight months and were observed for the development of chronic musculoskeletal conditions, behavioral health disorders, and inability to remain in active service as indicated by the findings of the Physical Evaluation Board. The influence of demographic factors, behavioral health conditions, and deployment-related musculoskeletal injuries on the capacity to remain in the military was assessed using Poisson multivariate analysis and receiver operating characteristic curves. Results The mean age of the cohort was twenty-seven years (range, eighteen to fifty-two years). One hundred and sixty-three soldiers sustained combat-related musculoskeletal trauma, and 587 soldiers had musculoskeletal injuries not related to battle. Three hundred and seventy-four soldiers (9%) were found to be unfit by the Physical Evaluation Board, with 236 soldiers (63%) referred for at least one musculoskeletal condition. Of these 236 soldiers, 116 (49%) also had a behavioral health diagnosis. Multivariate regression analysis revealed that junior enlisted rank (incidence rate ratio, 9.7 [95% confidence interval, 3.1 to 30.3]), senior enlisted rank (incidence rate ratio, 5.6 [95% confidence interval, 1.8 to 17.7]), behavioral health diagnosis (incidence rate ratio, 7.4 [95% confidence interval, 5.6 to 9.6]), age of eighteen to twenty-three years (incidence rate ratio, 1.6 [95% confidence interval, 1.2 to 2.3]), and male sex (incidence rate ratio, 2.5 [95% confidence interval, 1.2 to 5.0]) were significant predictors of referral to the Physical Evaluation Board for a musculoskeletal condition. A prognostic model developed using receiver operating characteristic curves and the risk factors of musculoskeletal injury, presence of a psychiatric condition, and lower rank explained 78% (95% confidence interval, 77% to 80%) of the risk of being found unfit by the Physical Evaluation Board. Conclusions Musculoskeletal conditions, psychological diagnoses, and lower rank