Abstract
Waist circumference (WC), an abdominal obesity index in the current metabolic syndrome (MetS) criteria, may not adequately reflect visceral fat accumulation. This brief review aims to examine the clinical significance of utilizing a body shape index (ABSI), a novel abdominal obesity index, to modify the MetS criteria, considering the predictive ability for vascular dysfunction indicated by the cardio-ankle vascular index (CAVI), as well as kidney function decline. First, the relationship of CAVI with kidney function is presented. Next, whether modification of the MetS diagnostic criteria by replacing the current high waist circumference (WC-MetS) with high ABSI (ABSI-MetS) improves the predictive ability for vascular and kidney dysfunction is discussed. Although limited to Asian populations, several cross-sectional and longitudinal studies support the relationship of CAVI with kidney function. Increased CAVI is associated with kidney function decline, and the CAVI cutoff for kidney outcomes is considered to be 8-9. In urban residents who underwent health screening, an increase in ABSI, but not body mass index (BMI) or WC, was associated with increased CAVI, suggesting that ABSI reflects vasoinjurious body composition. In several cross-sectional studies, ABSI-MetS was superior to WC-MetS in identifying individuals with increased CAVI. Furthermore, the predictive ability of ABSI-MetS in assessing kidney function decline was enhanced only in individuals with MetS, as determined in a longitudinal analysis. Using WC as a major criterion for MetS diagnosis may not adequately identify individuals at risk of vascular dysfunction and kidney function decline. This review shows that this problem may be solved by replacing WC with ABSI. Future research should explore whether ABSI-MetS also predicts cardiovascular events, and whether therapeutic intervention that reduces ABSI improves clinical outcomes.