Preenlistment and Early Service Risk Factors for Traumatic Brain Injury in the Army and Marine Corps: FY 2002-2010

Objective: To determine the preenlistment and early service risk factors for traumatic brain injury (TBI)-related disability in Army and Marine Corps service members. Design: Matched case-control design. Main Outcome: TBI disability discharges. Subjects: Army and Marine Corps service members with an enlistment record and disability discharge for TBI were included as cases. Controls were selected from the enlisted population with no disability evaluation record and were matched on fiscal year of enlistment, sex, and service at a ratio of 5: 1. Results: Older age at enlistment resulted in a significantly increased risk for TBI disability in the crude and adjusted models (adjusted odds ratio [aOR] = 1.49; 95% confidence interval [CI], 1.16-1.91). An enlistment military occupational specialty (MOS) with a combat arms designation resulted in an almost 3-fold increased odds of TBI disability compared with other MOS categories (aOR = 2.75; 95% CI, 2.46-3.09). This remained a significant risk factor for TBI disability in the multivariate model (aOR = 2.74; 95% CI, 2.45-3.08). Conclusion: Results from this study help inform the existing body of military TBI research by highlighting the preenlistment demographic and early service risk factors for TBI disability. Further research into the role of age on TBI disability in the military is merited.