Variation in the rate of well-controlled status of chronic disease by income level in Korea: 2010 to 2015.

Although it is known that the prevalence rates of chronic diseases depend on income level, annual changes of the control rate have not been evaluated. In this cross-sectional study, we analyzed the variation in rate of well-controlled status of chronic diseases based on the annual income level using data from national nutrition surveys conducted between 2010 and 2015.Prevalence and controlled rate of hypertension, diabetes mellitus, and chronic kidney disease were analyzed in relation to annual income levels, using data from the Korea National Health and Nutrition Examination Survey (KNHANES), obtained from 2010 to 2015. We also analyzed the incidence of use of necessary medical care services and the reasons cited for not using these services.The data of 28,759 persons were analyzed. The average age increased, and sex ratio remained unchanged over the study period. Although the prevalence rates of diabetes increased, that of increased glycated hemoglobin gradually decreased. A significant change has been shown recently on the prevalence rates of hypertension patients. The prevalence rates of chronic kidney disease stayed unchanged during the course of the study period. The incidence of controlled chronic disease status increased with the income level, and over time during the study, in the case of diabetes and chronic kidney disease. However, while controlled hypertension status rate increased from year to year, there was no trend of increase with increased income level. The incidence of participants not using hospital services declined with increasing income level, but the rate of economic causes being cited as reasons for not using hospital services increased over time and showed no change among income levels. Results of regression analysis of prevalence rates of chronic diseases by income level showed that lower income groups tended to have higher odds ratios for chronic diseases.Our results suggest that the incidence rate of well-controlled chronic disease status remains low in lower income groups. These results imply that financial status may play an important role in the management of chronic diseases.