Accuracy of skinfold and bioelectrical impedance assessments of body fat percentage in ambulatory individuals with cerebral palsy

Aim This study assessed the accuracy of measurements of body fat percentage in ambulatory individuals with cerebral palsy (CP) from bioelectrical impedance analysis (BIA) and skinfold equations. Method One hundred and twenty‐eight individuals (65 males, 63 females; mean age 12y, SD 3, range 6–18y) with CP (Gross Motor Function Classification System [GMFCS] levels I (n=6), II (n=46), and III (n=19) participated. Body fat percentage was estimated from (1) BIA using standing height and estimated heights (knee height and tibial length) and (2) triceps and subscapular skinfolds using standard and CP‐specific equations. All estimates of body fat percentage were compared with body fat percentage from dual‐energy X‐ray absorptiometry (DXA) scans. Differences between DXA, BIA, and skinfold body fat percentage were analyzed by comparing mean differences. Agreement was assessed by Bland–Altman plots and concordance correlation coefficients (CCC). Results BMI was moderately correlated with DXA (Pearson's r=0.53). BIA body fat percentage was significantly different from DXA when using estimated heights (95% confidence intervals [CIs] do not contain 0) but not standing height (95% CI −1.9 to 0.4). CCCs for all BIA comparisons indicated good to excellent agreement (0.75–0.82) with DXA. Body fat percentage from skinfold measurements and CP‐specific equations was not significantly different from DXA (mean 0.8%; SD 5.3%; 95% CI −0.2 to 1.7) and demonstrated strong agreement with DXA (CCC 0.86). Interpretation Accurate measures of body fat percentage can be obtained using BIA and two skinfold measurements (CP‐specific equations) in ambulatory individuals with CP. These findings should encourage assessments of body fat in clinical and research practices. What this paper adds BIA is an accurate assessment of body fat in ambulatory individuals with CP. Use of estimated heights in BIA analysis only slightly reduces the accuracy. CP‐specific skinfold equations are validated. CP‐specific equations have improved accuracy over the traditional Slaughter equations. Body fat can be accurately assessed using relatively inexpensive portable equipment. This article is commented on by Samson‐Fang on page 416 of this issue.