Ethnicity, Socioeconomic Status, and Health Disparities in a Mixed Rural-Urban US Community-Olmsted County, Minnesota

Abstract

Objective: To characterize health disparities in common chronic diseases among adults by socioeconomic status (SES) and ethnicity in a mixed rural-urban community of the United States.

Patients and methods: We conducted a cross-sectional study to assess the association of the prevalence of the 5 most burdensome chronic diseases in adults with SES and ethnicity and their interaction. The Rochester Epidemiology Project medical records linkage system was used to identify the prevalence of coronary heart disease, asthma, diabetes, hypertension, and mood disorder using International Classification of Diseases, Ninth Revision codes recorded from January 1, 2005, through December 31, 2009, among all adult residents of Olmsted County, Minnesota, on April 1, 2009. For SES measurements, an individual HOUsing-based index of SocioEconomic Status (HOUSES) derived from real property data was used. Logistic regression models were used to examine the association of the prevalence of chronic diseases with ethnicity and HOUSES score and their interaction.

Results: We identified 88,010 eligible adults with HOUSES scores available, of whom 48,086 (54.6%) were female and 80,699 (91.7%) were non-Hispanic white; the median (interquartile range) age was 45 years (30-58 years). Overall and in the subgroup of non-Hispanic whites, SES measured by HOUSES was inversely associated with the prevalence of all 5 chronic diseases independent of age, sex, and ethnicity (P<.001). While an association of ethnicity with disease prevalence was observed for all the chronic diseases, SES modified the effect of ethnicity for clinically less overt conditions (interaction P<.05 for each condition [diabetes, hypertension, and mood disorder]) but not for coronary heart disease, a clinically more overt condition.

Conclusion: In a mixed rural-urban setting with a predominantly non-Hispanic white population, health disparities in chronic diseases still exist across SES. The extent to which SES modifies the effect of ethnicity on the risk of chronic diseases may depend on the nature of the disease.

Figure 1. Comparison of odds ratios of each chronic condition by ethnicity between different SES group (reference: Non-Hispanic White subjects)

SES modified the effect of ethnicity on the prevalence of chronic diseases, and the interaction between SES and ethnicity depended on the nature of the disease. Specifically, the patterns in which SES modified the effect of ethnicity observed among minority groups were comparatively different for diabetes, hypertension, and mood disorder from CHD. In this Figure 1, odds of diabetes, hypertension, and mood disorder were generally increased with higher SES (above the median of HOUSES) in the minority subjects, especially African American subjects, relative to Non-Hispanic White subjects, controlling for age, gender and additional pertinent risk factors. However, such patterns appeared to be reversed for CHD.