Impact of metabolic syndrome definitions on prevalence estimates: a study in a Portuguese community

This study compared the prevalence of metabolic syndrome (MS) according to World Health Organization (WHO), National Cholesterol Education Program Third Adult Treatment Panel (NCEP-ATP III), International Diabetes Federation (IDF) and American Heart Association/ National Heart, Lung and Blood Institute (AHA/NHLBI) definitions, to evaluate how well the different classifications agreed. The study also compared their 10-year predicted risk of coronary heart disease (CHD) with the Framingham risk score (FRS). Some 886 women and 547 men aged 18-92 years were included in the study. Demographic and personal medical history data were obtained at interview. Four operational definitions of MS were used (those of the WHO, NCEP-ATP III, AHA/NHLBI and IDF). The prevalence of metabolic syndrome was found to be 26.4% (WHO criteria), 24.0% (NCEP-ATP III criteria), 41.9% (IDF criteria) and 37.2% (AHA/NHLBI criteria). According to the definition used, central obesity ranged from 41.9% to 75.1% and high blood pressure from 52.9% to 65.8%. Agreement between classifications ranged from 75.2% (kappa=0.47) to 90.4% (kappa=0.80) and was lower in males. The 10-year predicted risk of CHD by FRS was similar between the different definitions. IDF and AHA/NHLBI definitions resulted in a higher prevalence of MS than the NCEP-ATP III or WHO definition. Overall, however, good agreement was found between definitions, and the predicted 10-year of CHD risk was similar.