Socioeconomic gradients and inequalities in all-cause mortality and cardiovascular diseases: A retrospective cohort study using Korean NHANES-mortality linkage data

Objectives: Rapid economic growth in South Korea provides a valuable context for investigating how socioeconomic status (SES) impacts mortality and cardiovascular disease (CVD) risk in an emerging high-income Asian country. The objective of this study was to examine these associations in a general population and a subgroup with type 2 diabetes mellitus (T2DM). Study design: Retrospective cohort study. Methods: Data from the Korea National Health and Nutrition Examination Survey (KNHANES) linked to mortality records was used. A total of 48,190 participants including 6,382 patients with T2DM from the 2011–2020 KNHANES cohort were included and followed until death, a cardiovascular event (myocardial infarction or ischemic stroke), or the study endpoint. Results: Participants in the lowest income quintile had higher risks of mortality (Hazard ratio [HR]: 1.44, 95 % CI: 1.19–1.76) and CVD (HR: 1.35, 95 % CI: 1.05–1.74) compared to the highest quintile. Unemployed individuals had a higher mortality risk (HR: 1.34, 95 % CI: 1.19–1.51) than employed ones. Non-homeowners also had a higher mortality risk (HR: 1.46, 95 % CI: 1.20–1.77) than multi-homeowners. Participants with elementary school education or less had higher risks of mortality (HR: 1.59, 95 % CI: 1.32–1.93) and CVD (HR: 1.71, 95 % CI: 1.31–2.24) compared to college graduates. Among those with T2DM, unemployment (HR: 1.43, 95 % CI: 1.16–1.77) and low education (HR: 1.53, 95 % CI: 1.07–2.17) were associated with higher mortality. Conclusions: This analysis revealed significant associations of low SES with increased risks of mortality and CVD. Similar associations were observed in T2DM population for mortality outcomes.