Occupational Risk of Low-Level Blast Exposure and Health Outcomes: A Longitudinal Study of Postdeployment Army Enlisted Active Duty Soldiers

Objective: Evaluate the relationship between risk of occupational low-level blast (LLB) exposure and health outcomes (ie, substance use disorder, long-term opioid receipt, headaches, and back pain). We integrated 2 established military occupation–based LLB exposure risk classification strategies (Belding and colleagues and Carr and colleagues) to use military service occupation as a proxy for LLB exposure risk. Setting: Records were drawn from the Substance Use and Psychological Injury Combat Study and included Military Health System inpatient and outpatient care data, pharmacy fill records, and military history characteristics. Participants: Enlisted Army soldiers returning from an Afghanistan/Iraq deployment during fiscal years 2008–2014 (n = 477 746). Design: Longitudinal and observational with exposure and outcome periods before and after the date of return from the first deployment ending in the study period, respectively. Belding and Carr classification strategies were integrated to create a 5-level LLB exposure risk framework (ie, High-Belding & Carr, High-Belding Only, Medium-Belding Only, Mixed, Low-Belding Only). Main Measures: Outcomes were long-term opioid receipt and diagnoses of substance use disorder, headache (including migraine), and back pain; covariates included demographic and military history characteristics, exposure-period traumatic brain injury diagnosis, exposure-period mental health and self-harm/suicidal behavior, and exposure-period observation of outcomes measures. Results: Approximately 6.0% were classified as high exposure by the High-Belding & Carr classification, and 27.2% were classified as High-Belding Only. Comparing the High-Belding Only and High-Belding & Carr groups, respectively, with the Low-Belding Only group, survival models revealed elevated hazard ratios for long-term opioid receipt (1.29, P < .001; 1.33, P < .001) and substance use diagnoses (1.19, P < .001; 1.27, P < .001), somewhat elevated hazard ratios for headache (1.12, P < .001; 1.08, P < .001), and slightly lowered hazard ratios (0.98, P < .001; 0.98, P < .01) for back pain. Conclusion: Study results add to the existing research underscoring the urgency for advancing knowledge about LLB exposure and potential military health impacts and provide direction for future research.