The relationship of three common definitions of the metabolic syndrome with sub-clinical carotid atherosclerosis

Background Presence of the metabolic syndrome (MetS) increases a patientʹs risk for future cardiovascular disease. However, there is no consensus as to which of the proposed definitions should be used. Therefore, using carotid atherosclerotic burden as an index of cumulative effects of atherosclerotic risk factors, we assessed the association of the three commonly used MetS definitions with sub-clinical atherosclerosis in a primary prevention population and determined if this association was independent of the component risk factors. Methods and results A multi-ethnic cohort of 796 men and women without cardiovascular disease was assessed for demographics, risk factors, properties of the carotid arteries using ultrasound and presence or absence of MetS based on each of the World Health Organization (WHO), the National Cholesterol Education Program Expert Panel (NCEP) and the International Diabetes Federation (IDF) definitions. Using any definition, 29% of the cohort had MetS. After adjusting for age, gender, ethnicity and smoking status, participants with MetS had greater intima-media thickening and total area (intima-media area and focal lesion area combined) than participants without MetS. Only participants meeting the WHO MetS criteria had a greater prevalence of focal lesions. After further adjustment for the individual risk factor components of each MetS definition separately, none of MetS definitions was associated with any of the carotid artery measures. Conclusions All three MetS definitions were associated with measures of sub-clinical carotid atherosclerosis and these associations were entirely mediated through the risk factor components of MetS.