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.