Ann Intern Med

Does stratifying BMI by waist circumference better predict mortality risks?

July 23, 2025

Using waist circumference to stratify BMI categories modestly improved mortality risk assessment—with higher waist circumference conferring higher risk—according to this large prospective cohort study of postmenopausal women. Risk prediction was improved in two validation cohorts—but risk discrimination was improved in only one cohort.

Study details. This prospective cohort study (N=139,213 postmenopausal women; age, 50-79 years) included patients from the U.S. population-based, multi-center Women’s Health Initiative multicenter study as well as two additional cohorts used for validation; one of these cohorts had a higher prevalence of overweight/obese patients, the other drew patients from geographically diverse centers. BMI categories were: Normal (18.5 to <25 kg/m2), overweight (25 to <30), obesity-1 (30 to <35), obesity-2 (35 to <40), and obesity-3 (≥40). Prespecified waist circumference thresholds in centimeters were equal or greater than: 80, 90, 105, 115, 115 cm. Mortality prediction models with a BMI component were compared with and without BMI stratification by waist circumference. Median follow-up: 24 years.

Results: Multivariable-adjusted mortality risk using waist-circumference BMI stratification revealed that risks were consistently greater for larger vs. normal waist circumference. Women with normal/overweight BMI who had a large waist circumference had mortality risks similar to obesity-1 patients with normal waist circumferences. Women with obesity-1 and large waist circumferences had risks similar to obesity-3 patients with normal waist circumferences. Prediction models that incorporated waist circumference were used on data from the 2 validation groups. Risk stratification was improved in both validation groups; however, in the geographically diverse validation group, risk discrimination wasn’t improved.

Source:

Aragaki AK, et al. (2025, July 8). Ann Intern Med. Development and Validation of Body Mass Index-Specific Waist Circumference Thresholds in Postmenopausal Women : A Prospective Cohort Study. https://pubmed.ncbi.nlm.nih.gov/40623313/