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

Abstract

Background and objectives: 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.

Methods: 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.

Results: 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.

Discussion: 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.