All-cause and cause-specific mortality rates after severe extremity injuries among previously deployed active duty service members

Background: Previous research has shown that active duty military personnel who sustain extremity injuries while in service are at elevated risk for serious physical and psychological health issues that could affect their long-term functioning and quality of life yet longer-term mortality has not been studied in this population. Objective: To determine whether rates of all-cause and cause-specific mortality are elevated for active duty U.S. service members who sustained traumatic limb injuries in service, compared to the broader population of deploying service members. To assess differences in mortality rates between service members with traumatic limb injuries that did versus did not result in amputation. Design: Retrospective cohort study; archival Department of Defense deployment, personnel, medical, and death records were combined and analyzed. Standardized mortality ratios (SMR) adjusted for age, sex, and ethnoracial group, along with associated 95% confidence intervals (CIs), were calculated to directly compare all-cause and cause-specific mortality rates in each of the two injury groups to rates in the total study population. Setting: Not applicable. Participants: Service members who deployed in support of the global war on terror between 2001 and 2016 were eligible for inclusion; the final sample included 1,875,206 individuals surveilled through 2019. Intervention: Not applicable. Main Outcome Measures: All-cause and cause-specific mortality rates. Results: Overall, the number of deaths was over three times higher than expected among service members with amputations (SMR = 3.01; CI: 2.36–3.65), and nearly two times higher among those with serious limb injuries not resulting in amputation (SMR = 1.72; CI: 1.54–1.90) when compared to the larger study population. Rates for both internal and external causes of death were significantly elevated among those with limb injuries. Conclusions: Long-term mortality rates are elevated among service members with traumatic limb injuries, though mortality patterns may differ based on whether the injury results in amputation. Although further research into causal mechanisms is needed, these results may inform the development of interventions to improve long-term health outcomes among injured military personnel.