Blast Exposure and Risk of Recurrent Occupational Overpressure Exposure Predict Deployment TBIs

Traumatic brain injury (TBI) has been the leading cause of morbidity and mortality in recent military conflicts and deployment-related TBIs are most commonly caused by blast. However, knowledge of risk factors that increase susceptibility to TBI following an acute, high-level blast is limited. We hypothesized that recurrent occupational overpressure exposure (ROPE) may be one factor that increases susceptibility to mild TBI (mTBI) following blast.

Using military occupational specialty as a proxy, we examined the effects of high versus low ROPE on mTBI following blast exposure. Initial analyses included 111,641 active-duty-enlisted U.S. Marines who completed the 2003 or 2008 version of the Post-Deployment Health Assessment. Final analyses examined probable mTBI screens among Marines with at least one qualifying exposure as a function of whether the exposure was a blast and level of ROPE (N = 12,929). This study was approved by the Institutional Review Board at the Naval Health Research Center.

Blast and ROPE were both independently and jointly associated with a probable mTBI. Marines who experienced a blast (vs other qualifying exposure) and those in high (vs low) risk occupations were 1.07 and 1.23 times more likely to sustain a probable mTBI, respectively. Furthermore, among those who experienced a blast during deployment, those in high-risk occupations were 1.45 times more likely than those in low-risk occupations to sustain a probable mTBI.

Blast exposure and ROPE were independently associated with mTBIs, and Marines with both blast exposure during deployment and ROPE were especially likely to sustain an mTBI. This suggests that ROPE heightens the risk of mTBI following blast. Ongoing research is examining the severity, symptomology, and sequelae of TBIs as a function of ROPE.