Body Adiposity Index as a Predictor of Body Fat in an Oldest Old and Independent Cohort of Brazilian Older Adults.

Background: Anthropometry and body mass index (BMI) do not assess body composition or its distribution in older adults; thus, individuals may have different fat percentages but similar BMI values. The body adiposity index (BAI) was recently proposed as a feasible and inexpensive method for estimating the percentage of body fat based on measurements of hip circumference and height. The present study evaluated whether BAI and BMI are useful alternatives to dual-energy X-ray absorptiometry (DXA), which is rarely used in clinical practice, for predicting body fat in independent long-lived older adults.

Methods: In this cross-sectional study, we used DXA to calculate the percentage of body fat, which was compared with BAI and BMI values. We performed Pearson correlation analyses and used Cronbach's alpha, described by Bland and Altman, to compare the reliability between the indexes.

Results: Among 157 evaluated individuals (73.2% women, mean age 87±3.57 years), men had a lower percentage of total fat, as assessed by DXA, and lower BAI indices than women. The correlation between BAI and DXA was moderate (r=0.59 for men and r=0.67 for women, p<0.001). We confirmed the reliability based on Cronbach's alpha coefficients of 0.67 in men and 0.77 in women. We also observed that the BAI was strongly positively correlated with BMI in both men and women.

Conclusion: The BAI, used in combination with BMI, can be an alternative to DXA for the assessment of body fat in the oldest old in clinical practice, mainly women, and can be used to add information to BMI.