Community-level socioeconomic inequality in the incidence of ischemic heart disease: a nationwide cohort study

BACKGROUND: The purpose of this study was to confirm that inequalities in community-level social economic status (SES) do actually impact the incidence of ischemic heart disease (IHD) using the Korean population-based cohort study of the National Health Insurance Service-National Sample Cohort (NHIS-NSC) database. METHODS: This study used the NHIS-NSC database, a population-based cohort database established by the NHIS in South Korea. Community-level SES was classified into three categories, i.e. low, moderate, and high, according to the rank. The outcome measure of interest was IHD, which was defined according to the International Classification of Disease, 10th Revision (ICD-10) codes. RESULTS: In the low community-level SES group, the incidence of IHD was 3.56 per 1000 person years (cumulative incidence rate, 1.78%), and in the high community level SES group, it was 3.13 per 1000 person years (cumulative incidence rate, 1.57%). Multivariate analysis showed that the incidence of IHD was higher in the low community-level SES group (p = 0.029). The log-rank test showed that the cumulative incidence of IHD was higher in the low community level SES group than the high community-level SES group (adjusted hazard ratio, 1.16; 95% CI, 1.01-1.32). CONCLUSIONS: People living in areas with low community-level SES show an increased incidence of IHD. Therefore, intervention in active, health-risk behavior corrections at the local level will be required to reduce the incidence of IHD.