Agreement of two metabolic syndrome definitions and their association with subclinical atherosclerosis: multi-ethnic study of atherosclerosis cross sectional study

Background: The metabolic syndrome (MetS) is a cluster of abnormalities that increases cardiovascular risk. Two different current clinical definitions of MetS, World Health Organization (WHO) and National Cholesterol Education Program (NCEP) Adult Treatment Panel 3 (ATPIII) may differ in association with the atherosclerotic process. We quantified the agreement between the WHO and NCEP definitions and their association with subclinical atherosclerosis in the Multi-Ethnic Study of Atherosclerosis (MESA). Methods: We analyzed 2601 Caucasian-Americans (C), 800 Chinese-Americans (Ch), 1864 African-Americans (A), and 1483 Hispanic-Americans (H) with complete data for MetS classification from the baseline of the population-based study MESA. Coronary artery calcification (CAC, Agatston score) was quantified by electron beam or helical computed tomography (CT), and intimal-medial thickness of internal and common carotid arteries (IIMT, CIMT) by B-mode ultrasound. Results: The percentage positive agreement differed by ethnicity (Men: C, 65%; Ch, 58%; B, 67%; H, 74%. Women: C, 58%; Ch, 67%; A, 69%; H, 71%; P < .001). Fasting insulin measurement added to the association of the NCEP definition with presence of CAC (P < .001) and CIMT (P < .001, men; P < .002, women), while the waist-hip ratio metric of obesity adds to the association with CIMT (P < .001, men; .003, women). The NCEP threshold for low HDL was associated with CIMT independent of the WHO definition (men, P = .035; women, P = .043). These independent associations did not differ by ethnicity. Conclusion: Metabolic risk factors that differ between the NCEP and WHO MetS definitions are useful in combination to assess the presence of subclinical atherosclerosis.