Pooled analysis of all-cause and cause-specific mortality among Nordic military veterans following international deployment

OBJECTIVES: To investigate all-cause and cause-specific mortality risks, including deaths from external, cardiovascular and cancer causes, among deployed Nordic military veterans in comparison to the general population in each country. DESIGN: Pooled analysis. SETTING: Denmark, Norway, Finland and Sweden. PARTICIPANTS: Military veterans deployed between 1990 and 2010 were followed via nationwide registers and compared with age-sex-calendar-year-specific rates in the general population using pooled standardised mortality ratios (SMRs). MAIN OUTCOMES: All-cause and cause-specific mortality retrieved from each country’s Causes of Death Register, including deaths from external, cardiovascular and cancer causes. RESULTS: Among 83 584 veterans 1152 deaths occurred of which 343 were from external causes (including 203 suicides and 129 traffic/transport accidents), 134 from cardiovascular causes and 297 from neoplasms. Veterans had a lower risk of death from any cause (pooled SMR 0.58, 95% CI 0.52 to 0.64), external causes (0.71, 95% CI 0.64 to 0.79), suicide (0.77, 95% CI 0.67 to 0.89), cardiovascular causes (0.54, 95% CI 0.46 to 0.64) and neoplasms (0.78, 95% CI 0.70 to 0.88). There was no difference regarding traffic/transport accidents for the whole period (1.10, 95% CI 0.92 to 1.31) but the pooled point estimate was elevated, though not statistically significant, during the first 5 years (1.17, 95% CI 0.89 to 1.53) but not thereafter (1.01, 95% CI 0.77 to 1.34). For all other causes of death, except suicide, statistically significantly lower risk among veterans was observed both during the first 5 years and thereafter. For suicide, no difference was observed beyond 5 years. Judged from the country-specific SMR estimates, there was a high degree of consistency although statistically significant heterogeneity was found for all-cause mortality. CONCLUSIONS: Nordic military veterans had lower overall and cause-specific mortality than the general population for most outcomes, as expected given the predeployment selection process. Though uncommon, fatal traffic/transport accidents were an exception with no difference between deployed military veterans and the general population.