Associations of general and abdominal obesity with multiple health outcomes in older women - The Iowa women's health study

Background: Recent clinical guidelines on the health risks of obesity use b ody mass index (BMI; calculated as weight in kilograms divided by the squar e of height in meters) and waist circumference, but the waist-hip ratio may provide independent information. Methods: To assess the joint and relative associations of BMI, waist circum ference, and waist-hip ratio with multiple disease end points, we conducted a prospective cohort study of 31 702 Iowa women, aged 55 to 69 years and f ree of cancer, heart disease, and diabetes, assembled by random sampling an d mail survey in 1986. Study end points were total and cause-specific morta lity and incidence of site-specific cancers and self-reported diabetes, hyp ertension,and hip fracture over 11 to 12 years. Results: The waist-hip ratio was the best anthropometric predictor of total mortality, with the multivariable-adjusted relative risk for quintile 5 vs 1 of 1.2 (95% confidence interval, 1.1-1.4), compared with 0.91 (95% confi dence interval, 0.8-1.0) for BMI and 1.1 (95% confidence interval, 1.0-1.3) for waist circumference. The waist-hip ratio was also associated positivel y with mortality from coronary heart disease, other cardiovascular diseases , cancer, and other causes. The waist-hip ratio was associated less consist ently than BMI or waist circumference with cancer incidence. All anthropome tric indexes were associated with incidence of diabetes and hypertension. F or example, women simultaneously in the highest quintiles of BMI and waist- hip ratio had a relative risk of diabetes of 29 (95% confidence interval, 1 8-46) vs women in the lowest combined quintiles. Conclusion: The waist-hip ratio offers additional prognostic information be yond BMI and waist circumference.