Sex-specific long-term mortality inequities among North Korean refugees resettled in South Korea: a nationwide matched cohort study

Forced migration exposes populations to major changes in social, environmental, and health-system conditions, yet long-term mortality after resettlement remains poorly characterized. Comparisons between populations with shared ancestral and linguistic background who enter the same national health insurance system after migration may provide an opportunity to examine long-term mortality inequities associated with resettlement. Using Korean National Health Insurance Service data linked to national death records from 2002 to 2022, we conducted a nationwide matched cohort study. We included 26,123 eligible North Korean refugees aged 20 years or older after resettlement in South Korea and matched them to 1,300,144 South Korean residents in a 1:50 ratio by sex, birth year, and calendar year of cohort entry. All-cause and cause-specific mortality were assessed over up to 20 years of follow-up using Cox proportional hazards models adjusted for comorbidities and medication use, with sex-stratified and time-varying analyses. During 11.3 million person-years of follow-up (median, 10.0 years), mortality patterns differed by sex and time since resettlement. Male North Korean refugees had higher all-cause mortality than matched South Korean men throughout follow-up (adjusted hazard ratio, 1.68; 95% confidence interval, 1.52–1.86), with excess mortality from infection, trauma or injury, cancer, and cardiovascular disease. Among female North Korean refugees, all-cause mortality was lower than that of matched South Korean women during the first 6 years after resettlement (adjusted hazard ratio, 0.81; 95% confidence interval, 0.67–0.98), but this early advantage attenuated with longer residence. Infection- and trauma-related mortality was higher in refugees of both sexes. In this nationwide matched cohort study, mortality after resettlement differed by sex, cause of death, and time since resettlement. Persistent differences despite enrollment in a shared national health insurance system suggest that formal coverage alone may not fully address the long-term health effects of pre-migration deprivation, displacement, and post-resettlement social conditions. These findings support long-term, sex-specific monitoring of refugee health beyond the initial reception period.