Effect of the site of measurement of waist circumference on the prevalence of the metabolic syndrome.

Waist circumference (WC) is widely advocated as a marker of health risk and is a key diagnostic criterion for metabolic syndrome (MS); yet, there remains no uniformly accepted measurement protocol. The purpose of this study was to determine whether WC is differentially associated with cardiometabolic risk factors according to its anatomic measurement site and to quantify the impact of measurement site on prevalence of MS. The sample included 520 community-dwelling adults (208 men, 312 women). WC was measured at 4 common sites: the superior border of the iliac crest, midpoint between the iliac crest and the lowest rib, the umbilicus, and minimal waist. Blood pressure at rest was measured, and fasting blood samples were analyzed for concentrations of high-density lipoprotein cholesterol, triglycerides, and glucose. MS was diagnosed according to criteria of the American Heart Association/National Heart, Lung, and Blood Institute. Overall, patterns of association between WC and cardiometabolic risk factors were similar across anatomic locations of measurement. In men, prevalence of MS was the same when WC was measured at the iliac crest, the midpoint, or the umbilicus (21.2%), but was lower (18.3%) using the minimal waist. In women, prevalences of MS were 15.1%, 14.4%, 14.1%, and 13.1% using the umbilicus, iliac crest, midpoint, and minimal waist, respectively. In conclusion, prevalence of MS is modestly influenced by anatomic site of WC measurement. Efforts should be made to standardize the protocol for measurement of WC given its potential to influence research findings and clinical decision-making.