Sociodemographic disparities in the composition of metabolic syndrome components among adults in South Korea

Abstract

OBJECTIVE Metabolic syndrome (MetS) is becoming a serious public health concern in many countries, including South Korea, which has faced remarkable changes in lifestyles and disease patterns in recent decades. We examined sex and socioeconomic status (SES) disparities in MetS and its components among South Koreans using recent, nationally representative data. RESEARCH DESIGN AND METHODS Data from the 2007-2008 Korea National Health and Nutrition Examination Surveys for 7,289 adults 19-65 years of age were used to examine the patterns of MetS components (defined using International Diabetes Federation criteria), and regression models were used to study the association of MetS with SES, indicated by education and family income levels. RESULTS MetS prevalence increased with age, from 4.6% at age 19-29 years to 25.0% at age 50-65 years. More men had MetS than women (15.8 vs. 11.6%); men had worse levels of all MetS components. In women, the low-income and low-education group was more likely to have MetS (odds ratio 2.75 [95% CI 1.75-4.31]); the high-income and high-education group was 52% less likely to have MetS (0.48 [0.25-0.89]) compared with the middle-income and middle-education group. The most common combination of MetS components was central obesity + low HDL cholesterol (HDL-C) + hypertriglyceridemia, which occurred in 15.5% of all MetS patients and in 3.4% of all South Korean adults (4.1% in men and 2.9% in women). CONCLUSIONS Those who were older and male as well as low-SES female had higher rates of MetS and its components in South Korea. The SES-MetS association was not found in men. Central obesity + low HDL-C + hypertriglyceridemia was the most common MetS pattern regardless of the SES.

Figure 1

Comparison of prevalence (%) of metabolic outcomes by sex and SES among 19- to 65-year-old South Koreans: KNHANES 2007−2008. A: Male, solid line; female, dotted line. B: Low income, solid line; high income, dotted line. C: <HS, solid line; >HS, dotted line. D: Low income and low education, solid line; high income and high education, dotted line. ^aOutcomes were defined based on the 2006 IDF definition. ^bIncome was the quartiles of average household monthly income: low (Q1 + Q2), middle (Q3), and high (Q4). ^cEducation levels: <HS, HS, and >HS education. *P < 0.05, between-group difference was significant.

Figure 2

ORs (±SE) for MetS by education and family income among 19- to 65-year-old South Koreans: KNHANES 2007−2008. Low income and low education, ●; high income and high education, ○. Logistic regression model included age, sex, and urban-rural residence. Middle income and middle education was the reference group. Income was the quartiles of average household monthly income: low (Q1 + Q2), middle (Q3), and high (Q4). Education levels: HS education. *P < 0.05 for the null hypothesis that OR = 1.0.

Figure 3

Comparison of prevalence (%) of different combinations of MetS components by sex and SES among 19- to 65-year-old South Koreans: KNHANES 2007−2008. A: Male, ■; female, ○. B: Low income, ■; high income, ○. C: <HS, ■; >HS, ○. D: Low income and low education, ■; high income and high education, ○. G, blood glucose (hyperglycemia); H, HDL-C (low HDL-C); P, BP (hypertension); T, TG (hypertriglyceridemia); W, WC (central obesity). WPHTG, WC, BP, HDL-C, TG, and blood glucose. For example, WPHTG means that all MetS components (WC, BP, HDL-C, TG, and blood glucose) were included. W-HTG means that four groups (WC, HDL-C, TG, and blood glucose) were included and one MetS component (BP) was not included. ^aIncome was the quartiles of average household monthly income: low (Q1 + Q2), middle (Q3), and high (Q4). ^bEducation levels: <HS, HS, and >HS education. *P < 0.05, between-group difference was significant.