Although blast exposure is common for Service members serving in recent conflicts, blast events vary widely in key characteristics, and there is no agreed-upon definition of what constitutes a blast event. This makes it difficult to determine which aspects of blast exposure are most strongly correlated with negative outcomes such as traumatic brain injury (TBI).
Rowland and colleagues (Salisbury VA Medical Center; Salisbury, NC)1 developed an assessment tool, the Salisbury Blast Interview (SBI), to increasingly standardize assessment of blast events and further researchers' understanding of blast exposure and its health outcomes. The SBI is a structured interview in which participants are queried about their lifetime history of blast exposure. For each blast event, Service members responded to a series of yes/no and Likert scale questions describing the blast, including the blast's source, distance from the individual, and environmental factors that could impact the Service member's experience of the blast such as protective gear or reflective surfaces, and characteristics of the blast (e.g., pressure, sound, temperature). For blast characteristics, Service members rated each category from 0–5, with 1 indicating a slight change from conditions prior to the blast, 3 indicating a moderate change, and 5 indicating the largest change. Behavioral anchors were developed to provide context and improve reliability of the ratings. The SBI collects information on civilian exposures as well as military blast exposure (i.e., combat, deployment, in the course of military service).
The current study's population consisted of 287 combat-deployed Veterans of Operations Enduring Freedom, Iraqi Freedom, and New Dawn; individuals with a history of moderate or severe TBI or penetrating head injury were excluded. 94 percent of the study population reported at least one lifetime blast exposure, with 98.8 percent occurring during military service.
Providing a sense of the typical blast exposure, the SBI showed that 66 percent of Service members reported wearing a helmet during their blast exposure; 65 percent had an object between them and the blast source, and 62 percent wore body armor. 16 percent of blast exposures occurred within 10 feet of the source, and 44 percent occurred within 100 feet of the source.
TBI was reported by 19.7 percent of the sample. When blast characteristics were examined simultaneously across all blast events, only pressure and distance from blast were independently predictive of TBI incidence; wind, debris, ground shaking, temperature, and sound were not independent factors. When Service members with a history of blunt force TBI were removed from the sample, temperature was also found to be predictive of TBI. Based on additional statistical analysis, pressure was found to be the most important predictive factor of TBI. The authors also report that blast pressure was positively correlated with reports of current post-concussive symptoms and PTSD symptoms. The authors are optimistic that the SBI will increase our understanding of the characteristics of blast that are most strongly associated with TBI, informing crucial medical decisions in the aftermath of blast exposure and minimizing injury and mortality in operational scenarios.
1 Rowland, Jared A., Martindale, Sarah L., Spengler, Kayla M., Shura, Robert D., and Taber, Katherine H. "Sequelae of Blast Events in Iraq and Afghanistan War Veterans using the Salisbury Blast Interview: A CENC Study." Brain injury (2020).
This research was supported by grant funding from Department of Defense, Chronic Effects of Neurotrauma Consortium (CENC) Award [W81XWH-13-2-0095] and Department of Veterans Affairs CENC Award I01 CX001135-01 [I01RX002172-01]. This research was also supported by the Salisbury VA Health Care System and Mid-Atlantic (VISN 6) Mental Illness Research, Education, and Clinical Center (MIRECC).
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