Issue 123 Item 8 Waist Girth Predicts Cardiovascular Risk Better Than BMI

Waist circumference is a better indicator of cardiovascular (CV) risk than is body mass index (BMI). that, according to results from the National Health and Nutrition Examination Survey (NHANES) III published in the September issue of the American Journal of Clinical Nutrition. "Body fat distribution is a more powerful predictor than is BMI for risk factors, diseases, and mortality," write ShanKuan Zhu, from Columbia University in New York, N.Y., and colleagues. "Measurements that are more sensitive to individual differences in abdominal fat might be more useful than BMI for identifying obesity-associated risk factors."

Subjects from NHANES III, which surveyed the non-institutionalized US population from 1988 to 1994, included 4,388 white men with an average age of 44 years and 4,631 white women, average age 47 years. Average BMI was 26, within the overweight category, and average waist circumference was 96.4 cm for the men and 88.2 cm for the women.

Subjects were divided into two groups based on whether they had at least one of the following risk factors for CV disease: low high-density lipoprotein (HDL) cholesterol; high low-density lipoprotein (LDL) cholesterol; high blood pressure, and high glucose. Overall, 48.5% of men and 50.2% of women had at least one of these risk factors.

Waist circumference correlated more directly than did BMI with overall CV risk. Using receiver operating characteristic curves, the authors identified "cutoffs" of 90 cm (35 inches) for men and 83 cm (33 inches) for women. To minimize CV risk, they recommend advising patients with waist circumference at least as large as the cutoff value to lose weight.

"Waist circumference is more closely linked to CV disease risk factors than is BMI [so] it is inappropriate to base waist circumference thresholds on their association with BMI thresholds," the authors write. "Rather, thresholds for each should be based on their relation to risk factors."

In an accompanying editorial, Michael J. Lean and Thang S. Han discuss practical problems involved in clinical measurement of waist circumference. They recommend that future studies develop similar correlations for subjects of other races and for those who have other chronic diseases. Am J Clin Nutr. 2002; 76:743-9; 699-700