Cause-Specific Mortality Among Norwegian Veterans Deployed to Afghanistan Between 2001 and 2019

Introduction Norwegian military forces participated in the military campaign Operation Enduring Freedom in Afghanistan starting in 2001. Military personnel often show a "healthy soldier effect" in terms of lowered all-cause mortality when compared to the general population. However, military service in conflict areas is associated with an increased risk of death from external causes such as transport accidents and suicide after discharge. We aimed to investigate cause-specific mortality in a cohort of 9,192 Norwegian (7.5% women) veterans deployed to Afghanistan between 2001 and 2019. Materials and Methods We followed cohort members from their first day of service in Afghanistan through 2019. We computed standardized mortality ratios (SMRs) with 95% CIs by comparing the observed number of deaths in our cohort with the expected number of deaths in the general population. Standardized mortality ratios were calculated for the full follow-up period among men and women separately, and among men only for two time periods: during deployment and after discharge from service in Afghanistan. Results We observed 77 deaths (3 women and 74 men), 10 of which occurred during deployment (war casualties, 1 woman and 9 men); all others occurred after discharge. All-cause mortality in women did not differ from that in the general population (SMR = 0.52, 95% CI 0.11-1.53). For men, the observed all-cause mortality was lower than the expected rate for the full follow-up period (SMR = 0.55, 95% CI 0.43-0.69), during deployment, and after discharge, while deaths because of transport accidents after discharge (13 cases) were more than twice as high as expected rates (SMR = 2.36, 95% CI 1.26-4.04). The 11 observed suicides gave a nonstatistically significant, lower suicide risk compared to the expected rates (SMR = 0.66, 95% CI 0.33-1.18). Conclusion In accordance with the "healthy soldier effect," military service in Afghanistan was generally associated with a lower than expected risk of death both during deployment and after discharge. The risk of death from transport accidents was higher than expected after discharge, while the observed incidence of suicide did not differ from the expected rate in the general population.