Relations between waist circumference at four sites and metabolic risk factors.

The location of waist circumference (WC) measurement differs among diagnostic guidelines for the metabolic syndrome. The present study examined which of four WC measurements was associated most strongly with the clustering of metabolic risk factors in cross-sectional study. The subjects comprised 1,140 Japanese employees, aged 20-70 years, who underwent health examinations in 2007 and 2008. WC was measured at (i) the narrowest part of the waist, (ii) midway between the lowest rib and the iliac crest, (iii) the umbilical level, and (iv) immediately above the iliac crest. A receiver operator characteristic (ROC) curve was used to assess the ability of each WC measurement to predict the presence of two or more other components of the metabolic syndrome, as defined by the National Cholesterol Education Program's Adult Treatment Panel III (NCEP-ATP III) in 2005. Multiple risk factors were seen in 43.0% of the men and 12.9% of the women. The minimum and maximum WC measurements differed by 3.9 cm among the men and 12.6 cm among the women. The areas under the curve examining the ability of the four WC measurements to predict the clustering of multiple risk factors were similar. If the same WC cutoff value was applied, the prevalence of the metabolic syndrome changed considerably according to the site of WC measurement. The four WC measurements had similar screening abilities. Given the differences in the WC values according to the site of measurement, WC must be measured at the site specified by each diagnostic guideline.