A retrospective cohort study of traumatic brain injury-exposed military population and reported outcomes and recovery: A military traumatic brain injury initiative study

Abstract: INTRODUCTION: Traumatic Brain Injury (TBI) occurs after an external force on the brain results in injury and compromised ability to perform daily tasks. It is estimated that TBI affects 3-4 million people annually in the U.S. Military service members (SMs) are at higher risk of experiencing a TBI because of unique risk factors and recovery can also be different compared to civilians. This work focuses on a retrospective analysis of data in SMs providing an epidemiological description of TBI presentation and outcomes. METHODS: From 2010 to 2020, the Military Traumatic Brain Injury Initiative (MTBI2) sponsored protocol NCT03191357 recruited SMs and care-eligible participants into a natural history study. Data collected included TBI presentation, TBI history, injury type (civilian or military), combat exposure, and health measures capturing TBI symptoms including sleep, headache, and behavior.A retrospective cohort analysis focused on data at initial, 6-month, 12-month, and 24-month visits. The study population was described based on demographics including age, sex, race, and military factors (rank, combat, etc.). TBI was confirmed based on the TBI screener. Validated symptom measurements included National Institute of Neurological Disorders and Stroke common data element assessments. The analysis included independent samples t-test at each timepoint to compare means of category outcomes. Additional analysis of variance (ANOVA) was conducted for each assessment based on category. RESULTS: Initial data in the source protocol included 516 participants. History of TBI was reported in 469, 47 excluded for no TBI. The population was described as 59% White non-Hispanic, 16% Black; mean age 40.82; 77% male; 58% enlisted.The statistical analysis suggested evidence of higher Patient Health Questionnaire-9 (PHQ-9) and total symptom severity on Neurobehavioral Symptom Inventory (NSI) in females. Injury type measured differences in Epworth Sleep Scale (ESS), Posttraumatic Stress Disorder Checklist-5 (PCL-5), and NSI on independent samples t-test mean comparison along with Glasgow Outcome Scale-Extended (GOS-E) on repeated measures ANOVA. When comparing civilians to SMs, significant differences were observed in the PCL-5 and GOS-E, PHQ, Satisfaction with Life Scale, and symptom reporting on NSI. Combat exposure showed significant differences in the ESS and Short Form Survey-36. CONCLUSIONS: Results suggest some indication that determinants including sex, injury type, and rank influence TBI presentation and outcome. Despite group differences, consideration is needed for clinical relevance, specifically in assessments such as GOS-E. The outcomes identified in the population warrant more investigation into TBI prevention and care in SM focused on unique risk factors within this research population.