Injuries/Violence
Association of mild traumatic brain injury and risk of musculoskeletal injury among United States service members Alexander Ivan B. Posis* Alexander Ivan Posis James M. Zouris John J. Fraser Amy Silder Daniel J. Crouch Pinata H. Sessoms Andrew J. MacGregor
Background: Mild traumatic brain injury (mTBI) is associated with higher subsequent musculoskeletal injury (MSKI) risk. However, there is limited research on the association of mTBI on MSKI risk and if it is modified by sex among a large cohort of United States (US) service members (SMs) with extended follow-up while in service.
Methods: This retrospective cohort study included 777,811 SMs (mean age = 20.5 ± 3.4 years; 18.9% female; 53.7% White; mTBI = 2.6%) who enlisted between 2016-2020 and had medical record data until 2023. mTBIs were identified using International Classification of Disease, 10th revision codes defined by the Armed Forces Health Surveillance Division. Incident MSKI events were identified by anatomical complex, primary tissue type affected and International Classification of Functioning, Disability and Health codes. We used multivariable accelerated failure time models to estimate time ratios (TR) and 95% CIs, adjusted for demographic and military-relevant characteristics, for the association between mTBI and subsequent MSKI risk. We assessed effect measure modification (EMM) by sex testing an mTBI-by-sex interaction and conducted sex-stratified models.
Results: During 1,590,992 person-years of follow-up, there were 543,463 MSKI events (crude rate = 342 MSKIs per 1,000 person-years). mTBI was associated with a 52% (TR = 0.48, 95% CI 0.46-0.51) reduction in time to MSKI, relative to no mTBI. There was evidence to suggest EMM by sex (p-interaction <0.01). In sex-stratified models, mTBI was associated with a 41% (TR = 0.59, 95% CI 0.54-0.65) reduction in time to injury among females only and 54% (TR = 0.46, 95% CI 0.43-0.48) among males only.
Conclusions: In this large cohort of US SMs, mTBI was associated with shorter time to MSKI. The association was modified by sex, such that males had faster mTBI-associated time to MSKI compared to females. Findings suggest the importance of considering mTBI history and sex when assessing MSKI risk.