Traumatic Brain Injury Classification Variability During the Afghanistan/Iraq Conflicts: Surveillance, Clinical, Research, and Policy Implications.

OBJECTIVE:Challenges associated with case ascertainment of traumatic brain injuries (TBIs) sustained during the Afghanistan/Iraq military operations have been widespread. This study was designed to examine how the prevalence and severity of TBI among military members who served during the conflicts were impacted when a more precise classification of TBI diagnosis codes was compared with the Department of Defense Standard Surveillance Case-Definition (DoD-Case-Definition). SETTING:Identification of TBI diagnoses in the Department of Defense's Military Health System from October 7, 2001, until December 31, 2019. PARTICIPANTS:Military members with a TBI diagnosis on an encounter record during the study window. DESIGN:Descriptive observational study to evaluate the prevalence and severity of TBI with regard to each code set (ie, the DoD-Case-Definition and the more precise set of TBI diagnosis codes). The frequencies of index TBI severity were compared over time and further evaluated against policy changes. MAIN MEASURES:The more precise TBI diagnosis code set excludes the following: (1) DoD-only extender codes, which are not used in other healthcare settings; and (2) nonprecise TBI codes, which include injuries that do not necessarily meet TBI diagnostic criteria. RESULTS:When comparing the 2 TBI classifications, the DoD-Case-Definition captured a higher prevalence of TBIs; 38.5% were classified by the DoD-Case-Definition only (>164 000 military members). 73% of those identified by the DoD-Case-Definition only were diagnosed with nonprecise TBI codes only, with questionable specificity as to whether a TBI occurred. CONCLUSION:We encourage the field to reflect on decisions made pertaining to TBI case ascertainment during the height of the conflicts. Efforts focused on achieving consensus regarding TBI case ascertainment are recommended. Doing so will allow the field to be better prepared for future conflicts, and improve surveillance, screening, and diagnosis in noncombat settings, as well as our ability to understand the long-term effects of TBI.