Validation study of the body adiposity index as a predictor of percent body fat in older individuals: findings from the BLSA.

A new body adiposity index (BAI = (hip circumference)/((height)(1.5)) - 18) has been developed and validated in adult populations. We aimed to assess the validity of BAI in an older population. We compared the concordance correlation coefficient between BAI, body mass index (BMI), and percent body fat (fat%; by dual-energy X-ray absorptiometry) in an older population (n = 954) participating in the Baltimore Longitudinal Study of Aging. BAI was more strongly correlated with fat% than BMI (r of .7 vs .6 for BAI vs BMI and fat%, respectively, p < .01) and exhibited a smaller mean difference from fat% (-5.2 vs -7.6 for BAI vs BMI and fat%, respectively, p < .01) indicating better agreement. In men, however, BMI was in better agreement with fat% (r of .6 vs .7 for BAI vs BMI and fat%, respectively, p < .01) with a smaller mean difference from fat% (-3.0 vs -2.2 for BAI vs BMI and fat%, respectively, p < .01). Finally, BAI did not accurately predict fat% in people with a fat% below 15%. BAI provides valid estimation of body adiposity in an older adult population; however, BMI may be a better index for older men. Finally, BAI is not accurate in people with extremely low or high body fat percentages.