The Study on global AGEing and adult health (SAGE): Body Composition Measures among Ageing Populations

Abstract

As the global obesity epidemic continues to affect high-income countries, low- and middle-income countries have also begun to experience increases in overweight and obesity prevalence. Both overweight and obesity are major risk factors for many chronic diseases such as diabetes, cancer, and cardiovascular disease. Body mass index (BMI) is one common measure used to predict obesity-related health risks. However, because it estimates general adiposity instead of abdominal obesity, and does not distinguish between fat and lean mass, BMI is not a completely reliable predictor of cardiovascular and metabolic risk. Previous studies have generally found that measures of central obesity, including waist circumference (WC), to be better predictors of cardiovascular and metabolic risk than BMI, but no conclusion has been reached regarding the optimal measure of body composition. Furthermore, few studies have examined how body composition measures differ across various populations in older adults (≥50 years). The current study uses data from the World Health Organization Study on global AGEing and adult health (SAGE), a longitudinal study of nationally representative samples from older adults in six middle income countries (China, Ghana, India, Mexico, Russian Federation, and South Africa). This study examines associations among body composition measures (BMI, WC, and body adiposity index [BAI]) across age category, sex, and country. Furthermore, this study investigates associations between body composition measures and hypertension. Results indicate variability in body composition trends across age category, sex, and country. In general, both mean BMI and overweight and obesity prevalence were greater in 80+ age categories compared to younger age categories while mean BAI, mean WC, and increased risk (for obesity-related health diseases) prevalence were relatively similar across age categories. Logistic regression analyses were used to evaluate BMI, WC, and BAI as predictors of hypertension while controlling for covariates such as age, sex, smoking, drinking, and physical activity. All three body composition measures were fairly similar in their ability to predict hypertension. These findings suggest that BMI could be underestimating obesity-related health risks in population studies of older adults with the greatest underestimation in adults 80 years and older.