Trends in Traumatic Brain Injury Among U.S. Service Members Deployed in Iraq and Afghanistan, 2002-2016.

INTRODUCTION: Traumatic brain injury (TBI) is a major health issue for service members deployed and is more common in recent conflicts; however, a thorough understanding of risk factors and trends is not well described. This study aims to characterize the epidemiology of TBI in U.S. service members and the potential impacts of changes in policy, care, equipment, and tactics over the 15 years studied.

METHODS: Retrospective analysis of U.S. Department of Defense Trauma Registry data (2002-2016) was performed on service members treated for TBI at Role 3 medical treatment facilities in Iraq and Afghanistan. Risk factors and trends in TBI were examined in 2021 using Joinpoint regression and logistic regression.

RESULTS: Nearly one third of 29,735 injured service members (32.4%) reaching Role 3 medical treatment facilities had TBI. The majority sustained mild (75.8%), followed by moderate (11.6%) and severe (10.6%) TBI. TBI proportion was higher in males than in females (32.6% vs 25.3%; p<0.001), in Afghanistan than in Iraq (43.8% vs 25.5%; p<0.001), and in battle than in nonbattle (38.6% vs 21.9%; p<0.001). Patients with moderate or severe TBI were more likely to have polytrauma (p<0.001). TBI proportion increased over time, primarily in mild TBI (p=0.02), slightly in moderate TBI (p=0.04), and most rapidly between 2005 and 2011, with a 2.48% annual increase.

CONCLUSIONS: One third of injured service members at Role 3 medical treatment facilities experienced TBI. Findings suggest that additional preventive measures may decrease TBI frequency and severity. Clinical guidelines for field management of mild TBI may reduce the burden on evacuation and hospital systems. Additional capabilities may be needed for military field hospitals.