In-theater documentation of head injury was unavailable in DoD records for the large majority of cases (81%). Among Veterans who reported injuries that met diagnostic criteria for TBI on the BAT-L but were negative for TBI on DoD records (false negatives), 43% of cases did not have any DoD documentation of injury (in-theater or post-deployment notes). Importantly, when DoD documentation was available, injury events could be confirmed in the large majority of cases based on corresponding narratives, supporting the predictive validity of the BAT-L retrospective TBI diagnosis. These findings indicate that although DoD and military services made substantial efforts to increase TBI screening, documentation of injury assessment was rare. We cannot determine if the lack of available records is due to lack of reporting, lack of documentation, or more likely, a combination of these factors.
The BAT-L yielded a diagnostic sensitivity of 73% and specificity of 83% for TBI with available DoD records. Further analyses of TBI severity ratings indicated that sensitivity was 67% for mild TBI and 100% for moderate TBI. Sensitivity and specificity are inversely related; an increase in sensitivity will result in a decrease in specificity and vice versa.29 Due to this tradeoff, TBI assessment tools should be selected based on clinical utility. For example, initial screener tools, which have a primary goal of identifying all possible TBI, benefit from having higher sensitivity rates. After screening, individuals should receive a more comprehensive assessment to determine definitive diagnosis. Diagnostic agreement was lower for mTBIs, but was excellent for injuries of greater severity (moderate TBI).
The moderate correspondence observed for TBI diagnosis between the BAT-L clinical interview and DoD records was likely a result of multiple factors. Among the false negatives, six Veterans reported that they did not report injury or seek any care for their head injuries on the BAT-L. There are many potential reasons a Veteran may not report injury during deployment including lack of awareness they sustained a concussion, perceived stigma of TBI, a “battlemind” mindset related to military culture, confidentiality issues that may impact career advancement, and/or could delay returning home from deployment.3,5,14
Among those who were evaluated for TBI in-theater and had DoD documentation of the injury, there were four Veterans who reported (BAT-L) that they were mid-mission when their TBI event occurred and screened negative on in-theater TBI medic assessment. It is possible that these Veterans did not endorse symptoms because they did not want to disrupt their mission and/or wanted to return to the field.4
Another nine Veterans reported they were examined by a medic when queried specifically about in-theater medical attention during the BAT-L clinical interview. However, there was no documentation of any examination in DoD records. Although the reason(s) for lack of documentation is not clear, this issue is not unique. Terrio and colleagues used similar methods to compare the Warrior Administered Retrospective Casualty Assessment Tool with available DoD medical records among Veterans with a clinician confirmed TBI. Similarly, 73% of their sample had no corroborating documentation in their records.30 One reason mTBIs are not documented may be the co-occurrence of other serious injuries that required immediate attention.6 Four Veterans (of 23 false negative cases) were noted to have sustained other injuries (such as a fractured shoulder) that likely took precedence over mTBI assessment. Additionally, TBI assessments in battlefield conditions are understandably challenging. During combat/missions, the attending medic often provides triaged care, quickly evaluating a number of individuals, tending to critical needs first, or potentially participating in combat before he/she is able to attend to injuries. Documentation of mTBI under these circumstances may not always be feasible.
For Veterans who were evaluated and in-theater DoD documentation was available, there were a number of disagreements between the BAT-L and DoD records. The primary cause of the discrepancies was the differing nature of the TBI assessment tools. In-theater assessments necessarily involve briefer screening, usually limited to a symptom checklist format, designed to be more sensitive than specific, and prone to false positives errors to catch all potential injuries. Furthermore, the PDHA, which was admistered post-deployment, contained a single yes/no question to assess AMS. Service members were asked only if they were “dazed and confused or seeing stars.” Without additional information, endorsement of this single item may have also contributed to a high false positive rate, especially in the context of a combat situation (e.g., chaos of battle, stress, acute traumatic reaction).14
Comparatively, the BAT-L clinical interview adopts a more conservative, forensic approach including a detailed narrative and timeline for each injury event. Semi-structured diagnostic interviews administered by a qualified clinician are considered the criterion standard for diagnosing lifetime history of TBI.4,15 Combat settings pose unique diagnostic challenges given common co-occurring physical and psychological sequelae. Therefore, the BAT-L probes for eyewitness accounts, severity of other injuries, and other factors that may be misinterpreted as an acute symptoms of TBI. Examiners query the Veteran’s psychological state at the time of the head injury to provide context to assess whether confusion may be better explained by shock/acute trauma reaction. Lastly, the BAT-L guides the examiner to disentangle acute AMS symptoms from lingering PCS (e.g., generally slowed thinking versus acute disruption of thinking at the time of injury), which are often inappropriately lumped together in briefer screening assessments as demonstrated in at least one diagnostic discrepancy in this study. Thus, the BAT-L, by design, was more conservative in rendering a positive TBI diagnosis.
Although TRACTS Veteran self-selected for research participation, they are representative of US Veterans in terms of demographics, and other factors.25 Additionally, DoD documentation was limited to records available in the JLV system, which included both computer records and scanned, handwritten field notes. Paper records within DoD that have not been scanned to the JLV system may possibly provide additional information.