Validity of the body adiposity index in adults with Down syndrome.
BAI gives unreliable fat readings in adults with Down syndrome, so use DXA or validated limb measures instead.
01Research in Context
What this study did
The team compared the Body Adiposity Index (BAI) against a full-body DXA scan in adults with Down syndrome.
BAI uses hip and height numbers to guess body-fat percent. DXA shows real fat, so it acts as the gold ruler.
Researchers wanted to know if BAI is close enough for everyday clinic use.
What they found
BAI missed the mark. It overestimated body-fat for most adults with Down syndrome.
The error band was wide, so one person’s reading could be way too high or too low.
Because the mistakes were large and random, the authors label BAI “poor” for this group.
How this fits with other research
Johnson et al. (2009) already showed skinfold calipers flop in adults with severe ID, while tape measures around the limbs stay reliable. The new data say BAI, another hip-based shortcut, also flops, so simple tapes beat fancy formulas again.
Castañe et al. (1993) saw ACSM cardio equations over-predict VO2max by 84 % in Down syndrome. Nickerson et al. (2015) now show BAI over-predicts fat by a wide margin. Both papers send the same warning: standard equations built on typical adults break when used on adults with Down syndrome.
Mount et al. (2011) urged routine DXA screening for bone health in this population. Using DXA here to expose BAI’s weakness strengthens that call: if you already need the scan for bones, use it for fat rather than trusting a quick formula.
Why it matters
When you write a health plan, you need true body-fat numbers to set weight goals, check metabolic risk, and justify insurance requests. BAI can mislabel someone as obese or as healthy, derailing reinforcement menus and diet contracts. Stick with DXA, or at least BMI paired with tibia length, until tools built and tested for Down syndrome arrive.
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02At a glance
03Original 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%.
Research in developmental disabilities, 2015 · doi:10.1016/j.ridd.2014.12.010