Validity of the body adiposity index in adults with Down syndrome

Abstract

The purpose of this investigation was to determine the agreement between the body adiposity index (BAI) and dual energy X-ray absorptiometry (DXA) for measuring BF% in adults with Down syndrome (DS). Twenty adults (male: n=10; female: n=10) with Down syndrome volunteered to participate in this study. Criterion BF% was determined by DXA and predicted BF% was estimated by the BAI method. There was a significant mean difference (p<0.001) between DXA BF% (39.94±10.80%) and the BAI BF% (42.60±8.19%). The correlation between the two BF% variables was large and significant (r=0.73, p<0.001). However, the standard error of the estimate and total error was 7.79% and 7.86%, respectively. Additionally, the 95% limits of agreement ranged from 12.21% below to 17.52% above the constant error of 2.65%. Our findings suggest that on average, the BAI significantly overestimated BF% when compared to DXA values. Though there was a strong correlation between both methods, the wide limits of agreement suggest there is large amount of individual error when estimating BF% via the BAI. Therefore, the use of the BAI for individuals with DS does not appear to be accurate for estimating BF%.

Keywords: Adiposity; Body composition; Developmental disabilities; Physical fitness; Trisomy 21.