Association Of Musculoskeletal Injury And Mild Traumatic Brain Injury Among United States Service Members

PURPOSE: To test whether a prior musculoskeletal injury (MSKI) is associated with subsequent mild traumatic brain injury (mTBI) and if this relationship differs by sex among United States (US) service members. METHODS: This population-based retrospective cohort study included 786,882 US service members who enlisted from 2016 to 2020 and had relevant data in the Military Health System Data Repository through 2023. mTBI cases were identified using International Classification of Disease, 10th revision codes defined by the Armed Forces Health Surveillance Division. MSKIs were identified by anatomical complex, primary tissue type affected and International Classification of Functioning, Disability and Health codes. Multivariable logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for the association of mTBI status with MSKI history, adjusted for sex, age, race, ethnicity, rank, occupation, and service branch. We assessed sex differences by testing an MSKI-by-sex interaction and conducting sex-stratified analyses. RESULTS: Participants were 81.0% male, with an average age of 20.6 ± 3.4 years. There were 19,931 mTBI cases. In the multivariable model, regardless of MSKI status and covariates, females had higher odds of mTBI compared with males (OR = 1.43, 95% CI 1.38-1.48). Regardless of sex and covariates, prior MSKI was associated with higher odds of subsequent mTBI (OR = 1.54, 95% CI 1.49-1.60). Among males only, MSKI was associated with higher odds of mTBI compared with analyses of females only (males only: OR = 1.61, 95% CI 1.54-1.67; females only: OR = 1.27, 95% CI 1.17-1.38; p-value for interaction <0.01). CONCLUSION: Among almost 800,000 US service members, those with a prior MSKI had higher odds of a subsequent mTBI during an up to 7-year time frame. Females in this cohort had lower odds of MSKI-associated mTBI compared with males in sex-stratified models. Table - Participant Characteristics by Mild Traumatic Brain Injury (mTBI) Status Characteristic No mTBI (n = 766,951) mTBI (n = 19,931) p-value MSKI Yes 535,199 (69.78%) 16,180 (81.18%) <0.01 Sex Female 144,445 (18.83%) 4,788 (24.02%) <0.01 Male 622,506 (81.17%) 15,143 (75.98%) Age at entry, years,mean (SD) 20.57 (3.39) 20.16 (3.02) <0.01 Race/ethnicity Asian 45,220 (5.9%) 994 (4.99%) <0.01 Black 130,770 (17.05%) 3,478 (17.45%) White 412,137 (53.74%) 11,312 (56.76%) Hispanic/Latino 151,569 (19.76%) 3,592 (18.02%) American Indian/Alaska Native; Other; Unknown 27,253 (3.55%) 555 (2.78%) Occupation Non-combat 605,948 (79.95%) 15,155 (76.13%) <0.01 Combat 151,958 (20.05%) 4,752 (23.87%) Rank Enlisted 749,677 (97.75%) 191,00 (95.83%) <0.01 Officer 17,274 (2.25%) 831 (4.17%) Service branch Army 291,603 (38.02%) 10,853 (54.45%) <0.01 Air Force 150,181 (19.58%) 2,972 (14.91%) Marine Corps 146,454 (19.1%) 3,537 (17.75%) Navy 178,713 (23.3%) 2,569 (12.89%) This work was supported by the Assistant Secretary of Defense for Health Affairs, through the Congressionally Directed Medical Research Programs (CDMRP) Traumatic Brain Injury and Psychological Health Research Program (TBIPHRP) (award no. CDMRPL-22-0-TP210321) under work unit no. 62333.