Risk of post-traumatic stress disorder and other mental disorders among professional military personnel in the Republic of Korea: a nationwide cohort study

INTRODUCTION: Military personnel face unique occupational stressors that increase the risk of post-traumatic stress disorder (PTSD) and other mental disorders, but population-based evidence from Asian military populations remains limited. We compared the risk of PTSD and other mental disorders between professional military personnel and reference populations in the Republic of Korea. METHODS: We conducted a retrospective cohort study using nationwide health insurance claims data from 2002 to 2021. We identified 544 709 professional military personnel, 4 054 102 individuals in the working population and 5 474 515 individuals in the general population. The primary outcome was incident PTSD; secondary outcomes included stress-related disorders, depressive episodes, recurrent depressive disorder, anxiety disorders and alcohol use disorders. HRs were estimated using Cox proportional hazards regression adjusted for age and sex. RESULTS: Among 544 709 professional military personnel followed up for 20 years, 579 PTSD cases were identified (crude incidence rate: 1.45 per 10 000 person-years). The HR for PTSD was 1.45 (95% CI 1.32 to 1.60) compared with the general population and 1.41 (95% CI 1.27 to 1.56) compared with the working population. Male military personnel had an HR of 1.23 (95% CI 1.10 to 1.38), while female military personnel had an HR of 3.85 (95% CI 3.07 to 4.81) compared with the general population. Stress-related disorders were also elevated (HR 1.36, 95% CI 1.32 to 1.40). In contrast, military personnel had lower risks of depressive episodes (HR 0.84), recurrent depressive disorder (HR 0.59), anxiety disorders (HR 0.83) and alcohol use disorders (HR 0.51) compared with the general population. CONCLUSIONS: Professional military personnel in the Republic of Korea had elevated PTSD risk, with particularly high risk among female service members. The lower risks of other mental disorders were consistent with the healthy worker effect. These findings support enhanced mental health surveillance for military personnel.