Waist Circumference for the Clinical Diagnosis of Metabolic Syndrome in the Japanese Population: Optimal Cut-Point to Predict Early Arteriosclerosis

Abstract

Metabolic syndrome (MetS) has been proposed as a syndrome in an individual with clustered metabolic dysfunction including increased abdominal adiposity, raised blood pressure, raised triglyceride and/or reduced HDL cholesterol and raised fasting plasma glucose. At the time of writing, several definitions for clinical diagnosis of MetS have been proposed by different organizations. Clinical methods to evaluate visceral adiposity include abdominal computed tomography, body mass index, and waist and hip circumference; in which waist circumference is the most available, but is highly dependent on the ethnicity. Current MetS definitions include waist circumference as a surrogate marker for visceral adiposity and adapt cut-points of waist circumference for each ethnic group to optimize their predictive values. For Asians, the International Diabetes Federation (IDF), the American Heart Association and the National Heart, Lung and Blood Institute have provided the waist cut-points as 90 cm for men and 80 cm for women as recommended by the World Health Organization. By contrast, the previous IDF definition and the Japanese Committee for the Diagnostic Criteria of Metabolic Syndrome adopted waist cut-points of 85 cm for Japanese men and 90 cm for Japanese women which were derived from the cut-points of visceral fat area by computed tomography to identify clustered risk factors. After the MetS definitions were published, waist cut-points for the Japanese population have been re-evaluated in several studies. Our recent studies obtained optimal waist cut-points (87 cm for men and 80 cm for women) from the relation between waist circumference and risk factor clustering in a Japanese population. It showed superior sensitivity and specificity to the conventional IDF (90 cm), which is also the cut-points for Japanese women (90 cm), to predict intima-media thickening; it also agreed with the revised IDF definition (80 cm) for women. These studies suggest that the waist cut-points of 90 cm for men and 80 cm for women are relevant for Japanese population to define MetS with a short-term risk of development of atherosclerosis. Further studies with larger population and longer follow-up period may validate these waist cut-points for the clinical diagnosis of MetS with a substantial risk of cardiovascular events and/or onset of type 2 diabetes.