Linking Military Blast Exposure to Veterans Health Administration Diagnoses: Chronic Health Outcomes in the Millennium Cohort Study.

Abstract

To examine associations between high-level blast (HLB) exposure and occupational risk for low-level blast (LLB) exposure during military service and subsequent chronic medical diagnoses among US Veterans receiving Veterans Health Administration (VHA) care. The Millennium Cohort Study is a population-based cohort study of US service members and Veterans enrolled beginning in 2001 and followed with surveys every 3-5 years. Analyses included participants enrolled between 2001 and 2013 who completed the 2011-2013 survey, had separated from military service, had complete blast and covariate data, and used VHA care for at least 2 calendar years during follow-up. HLB was assessed by self-report of injury resulting from blast or explosion. LLB risk was classified using military occupational specialty codes. Incident VHA-documented diagnoses from 2013 to 2021 were analyzed using modified Poisson regression to estimate adjusted prevalence ratios (APRs) and 95% CIs. Among N = 36,641 Veterans, HLB exposure was associated with increased likelihood of several VHA-documented incident diagnoses, including hepatitis B (APR [1.46]; 95% CI [1.13-1.89]), hepatitis C (1.89; [1.30-2.75]), diabetes (1.28; [1.07-1.52]), hypercholesterolemia (1.31; [1.18-1.46]), hyperlipidemia (1.12, [1.06-1.18]), obesity (1.07, [1.01-1.15]), seizures (1.79; [1.47-2.18]), angina (1.43; [1.18-1.73]), hypertension(1.08; [1.02-1.15]), other heart condition (1.15; [1.05-1.28]), stroke (1.35; [1.05-1.74]), chronic bronchitis (1.28; [1.07-1.52]), emphysema (1.26; [1.05-1.52]), sinusitis (1.13, [1.04-1.23]), neuropathy (1.38; [1.24-1.54]), and bladder infection (1.54; [1.14-2.08]). Occupational risk for LLB exposure was associated with lower likelihood of hepatitis C (0.67; [0.45-0.97]), diabetes (0.84; [0.72-0.99]), hyperlipidemia (0.94; [0.90-0.99]), sinusitis (0.91; [0.85-0.99]), and Crohn disease (0.62; [0.41-0.94]). A significant multiplicative interaction was observed for hepatitis B (1.92; [1.13-3.25]). Additive interaction estimates were generally subadditive, suggesting that high occupational risk for LLB attenuated rather than amplified the associations between HLB and most outcomes. Among Veterans receiving VHA care, HLB exposure during military service was associated with a higher prevalence of several clinical conditions years after separation from service. These findings suggest that blast exposure represents a long-term occupational health risk with implications for neurologic disease burden and systemic health.