Waist and hip circumferences and all-cause mortality: usefulness of the waist-to-hip ratio?

OBJECTIVE

To investigate whether waist and hip circumferences, in addition to body mass index (BMI), are related to all-cause mortality. We studied these associations and tested the usefulness of the waist-to-hip ratio for mortality prediction.

DESIGN

A Danish prospective cohort study with data collected between 1993 and 1997.

SUBJECTS

A total of 27 179 men and 29 875 women born in Denmark and aged 50-64 years were followed for a median of 6.8 years.

MEASUREMENTS

BMI, waist and hip circumferences at baseline.

RESULTS

The associations between hip circumference and all-cause mortality were inverse for both men and women, but only after adjustment for waist circumference, or BMI, or both. The mortality rate ratios of mutually adjusted waist and hip circumferences were 0.63 (95% CI: 0.56, 0.71), and 0.70 (95% CI: 0.63, 0.79) times higher per 10% larger hip circumference in men and women, respectively, and 1.45 (95% CI: 1.34, 1.57) and 1.22 (95% CI: 1.14, 1.31) times higher per 10% larger waist circumference. The adequacy of the waist-to-hip ratio as a substitute for separate measurements of waist and hip circumferences depended on which other variables the analysis was adjusted for, indicating that the waist-to-hip ratio should be used with precaution.

CONCLUSION

When mutually adjusted, waist and hip circumferences show opposite associations with all-cause mortality, probably due to different effects of adipose tissue in the abdominal and gluteofemoral regions. The waist-to-hip ratio cannot always capture these relations adequately.