Estimating body composition in children with Duchenne muscular dystrophy: comparison of bioelectrical impedance analysis and skinfold-thickness measurement

Background: Duchenne muscular dystrophy (DMD) is often associated with obesity, which worsens the handicap early in the course ofthedisease.Nutritionalassessment,however,canbedifficultand often misleading in DMD. Objective: Two methods of estimating body composition in DMD, skinfold-thickness (ST) measurement and bioelectrical impedance analysis (BIA), were compared with a reference method, labeled water dilution (WD). Design: Body composition was estimated by using ST measurements and BIA (50 kHz, 800 mAmp), as well as the WD method (1 mL H2 18 O/kg) in 11 DMD patients with a mean (SD) age of 10.0 2.5 y. Results: When compared with the WD method, ST measurement significantly(P0.01)overestimatedfat-freemass(FFM)(x SD ST: 24.5 5.9 kg; x SD WD: 18.2 2.5 kg), which led to an underestimation of the percentage of fat mass (%FM) (ST: 23.3 10.4%; WD: 40.1 17.1%; P 0.05). In contrast, estimates obtainedwithBIA(FFM:21.54.5kg;%FM:31.313.9%)didnot differ from those obtained with WD. The difference from the reference method was less for BIA (x: 3.3 kg; 95% CI: 0.8, 4.9 kg) than for ST (6.3 kg; 2.2, 8.6 kg). WD and BIA defined 73% and 55%, respectively, of the children as obese (%FM associated with body mass index cutoffs for obesity), whereas ST measurements defined 9% as obese (P 0.01). Conclusions: Body-composition estimates by BIA are closer to those by WD than are those by ST measurement. Early detection of fat accumulation and longitudinal monitoring of nutritional care are 2 relevant applications of BIA to prevent obesity and hence lessen the burden of DMD. Am J Clin Nutr 2006;83:65–9.