Waist-Hip-Ratio as a Predictor of All-Cause Mortality in High-Functioning Older Adults

Purpose

The relationship between obesity and mortality in older adults is debated, with concern that body mass index (BMI) may be an imperfect measure of obesity in this age group. We assessed the relationship between three measures of obesity and all-cause mortality in a group of healthy older adults.

Methods

We analyzed data from the MacArthur Successful Aging Study, a longitudinal study of high-functioning men and women, ages 70–79 years at baseline. We examined 12-year, all-cause mortality risk by BMI, waist circumference, and waist-to-hip circumference ratio (WHR). Proportional hazards regression was used to adjust for gender, race, baseline age, and smoking status. We tested for obesity interactions with gender, race, and smoking status and conducted stratified analyses based on the results of interaction testing.

Results

There was no association between all-cause mortality and BMI or waist circumference in either unadjusted or adjusted analyses. In contrast, all-cause mortality increased with WHR. There was an interaction with sex, so that there was a graded relationship between WHR and mortality in women (relative hazard, 1.28 per 0.1 increase in WHR; 95% confidence interval, 1.05–1.55) and a threshold relationship in men (relative hazard 1.75 for WHR>1.0 compared to WHR≤1.0; 95% confidence interval, 1.06–2.91).

Conclusion

WHR rather than BMI appears to be the more appropriate yardstick for risk stratification of high-functioning older adults.

Key words: Geriatric Assessment, Health Status Indicators, Mortality, Obesity, Waist-Hip Ratio

Selected Abbreviations and Acronyms: BMI, body mass index, WC, waist circumference, WHR, waist-to-hip circumference ratio, NDI, National Death Index