Prevalence of chronic disease and its controlled status according to income level

The relationship between the prevalence of chronic diseases and income level has now become a main theme in poor national economic situations. We examined the prevalence of well-controlled chronic diseases according to income level. Data from the 2008 to 2014 Korea National Health and Nutrition Examination Survey, conducted by using a stratified, multistage, probability-cluster sampling method, were used. Systolic blood pressure (SBP) inversely correlated with income level (P < 0.001). Diastolic blood pressure (DBP) showed no relationship. In the low-income group, the prevalence rates of hypertension and diabetes mellitus (DM) were highest but the proportion of patients with well-controlled chronic disease and the SBPs of the patients with hypertension showed a decreasing trend. In the high-income group, the proportions of patients with well-controlled DM and chronic kidney disease were higher than those in other groups. After adjusting for age, body mass index, SBP, DBP, HbA1c level, and serum creatinine level, income level significantly affected the prevalence of chronic diseases (for income, β=0.184; 95% confidence interval, 1.105-1.042). The daily sodium intake estimated by using spot urine samples was higher in the low- and low-to-mid-income groups. The prevalence of not using essential medical service for chronic disease was highest in the low- and low-to-mid-income groups for economic reasons. In the low- and low-to-mid-income groups, the prevalence of chronic disease was higher and the proportion of patients with well-controlled chronic disease was lower than in the other groups.