Adjustment Disorders, Not Post-Traumatic Stress Disorder: Mental Health Burden Among Conscription-Based Military Personnel in the Republic of Korea

INTRODUCTION: Military mental health research has predominantly focused on post-traumatic stress disorder (PTSD) in Western volunteer forces. Although conscription-based military systems exist in approximately 60 countries-including Israel, Finland, Taiwan, Singapore, and South Korea-the diagnostic landscape of mental disorders in conscript populations remains poorly characterized. This study examined the epidemiology and risk factors of mental health diagnoses recorded in the Korean military healthcare system, examining whether the diagnostic patterns documented in Western volunteer forces apply to a conscription-based system. MATERIALS AND METHODS: In this retrospective cohort study, 2,251,713 military personnel (161,187,091 person-months; May 2012-December 2022) were analyzed using a 2-level design. Level 1 described the overall mental health burden (ICD-10 F00-F99). Level 2 focused risk factor analysis on adjustment disorders (F43.2), identified as the primary diagnostic category. Negative binomial generalized linear mixed models estimated incidence rate ratios (IRR). Methodological triangulation integrated inverse probability weighting, Cox proportional hazards regression, and competing risks analysis. The Institutional Review Board of the Armed Forces Medical Command approved this study (File No: 2023-08-001); informed consent was waived because of the retrospective nature and use of de-identified administrative data. RESULTS: Adjustment disorders (F43.2) accounted for 69.8% of all mental health diagnoses and 97.1% within the F43 stress-related disorder block. Trainees had the highest adjusted incidence (IRR = 4.80; 95% CI: 4.40-5.23), followed by full-time reserve soldiers (3.97; 3.43-4.60), relative to non-commissioned officers. Male sex was associated with lower rates (IRR = 0.50; 0.46-0.54). Navy personnel showed a protective association for F43.2 (0.86; 0.81-0.92) but elevated composite mental health rates (1.12; 1.08-1.16), reflecting disproportionate PTSD burden. Incidence rates declined at -4.8% per year after 2015. Triangulation across methods provided convergent evidence for most comparisons. CONCLUSIONS: Adjustment disorders-not PTSD-constitute the primary mental health burden in this conscription-based military system. These findings indicate that PTSD-centric frameworks derived from volunteer-force research may not apply to conscription-based systems, where transition-stress prevention may warrant greater priority than deployment-focused PTSD programs. The structural features of conscription systems-involuntary entry, hierarchical authority, and restricted autonomy-may shape a diagnostic distribution distinct from that observed in volunteer forces.