Is a single definition of the metabolic syndrome appropriate? - A comparative study of the USA and Asia

The metabolic syndrome has been identified as an increasingly important precursor to cardiovascular diseases in many Asian populations. Our objective was to compare the contribution of component risk factors to the diagnosis of the metabolic syndrome, as defined by the Third report of the National Cholesterol Education Program Expert Panel Adult Treatment Panel (NCEP-ATPIII), in the US and selected Asian populations. Nationally representative survey data from Hong Kong, Taiwan, Thailand and the US were used. Analyses were restricted to men and women aged ≥35 years. The age-standardized prevalence of the NCEP-ATPIII defined metabolic syndrome was highest in the US (31% in men, 35% in women), and lowest in Taiwan (11% in men, 12% in women). The component risk factors that defined the presence of the metabolic syndrome varied between countries. As expected, abnormal waist circumference was considerably more prevalent among individuals with the metabolic syndrome in the US (72% in men, 94% in women) compared with their Asian counterparts, but substantial variation was also observed between the Asian populations (13-22% in men, 38-63% in women). Furthermore, the relative contribution of other risk factors to the metabolic syndrome was also substantially different between countries. The NCEP-ATPIII definition identifies a heterogeneous group of individuals with the metabolic syndrome in different populations.