Measurement of body composition in 8-10-year-old African-American girls: a comparison of dual-energy X-ray absorptiometry and foot-to-foot bioimpedance methods.
OBJECTIVE
The purpose of this study was to evaluate body composition outcomes of foot-to-foot (FF) bioelectrical impedance (BIA) and dual-energy x-ray (DEXA) in 8 to 10-year-old African-American girls and, if different, to develop and cross-validate specific BIA prediction equations for this at-risk group.


METHODS
DEXA and FF-BIA body composition outcomes were analyzed in 183, 8-10-year-old African-American girls from the Memphis site of the Girls health Enrichment Multi-site Study (GEMS).


RESULTS
Mean body composition outcomes by FF-BIA and DEXA were significantly different (p<0.0001); therefore, population-specific equations were developed and cross-validated using split-sample, cross-validation methods. When equations were used, BIA and DEXA outcomes were significantly correlated (percent body fat [r=0.931], fat mass [r=0.985], and fat-free mass [r=0.944]). Mean predicted BIA measurements for body fat, fat mass, and fat-free mass were essentially equal to their counterpart DEXA measurements (t[182]=- 0.013, p = 0.897, t[182]=- 0.06, p=0.956, and t[182]=- 0.26, p=0.792, respectively). The Bland-Altman analysis revealed a significant slope for percent fat (p=0.009) and slopes approaching significance for fat mass (p=0.07) and fat-free mass (p=0.06).


CONCLUSIONS
Although FF-BIA and DEXA are not directly interchangeable in young African-American girls, these equations accurately estimated average percent fat, fat mass, and fat-free mass of the cross-validation sample of African-American girls. However, the application of this equation may result in potential underestimation or overestimation of fat with respect to DEXA measures in some populations.
McClanahan
Barbara S
BS
Department of Health and Sport Sciences, University of Memphis, Memphis, TN 38152, USA. bmcclnhn@memphis.edu
Stockton
Michelle B
MB
Lanctot
Jennifer Q
JQ
Relyea
George
G
Klesges
Robert C
RC
Slawson
Deborah L
DL
Schilling
Leslie P
LP
D015502:Absorptiometry, Photon; D050154:Adiposity / Q000208:ethnology; D044383:Black People; D001823:Body Composition; D015992:Body Mass Index; D002648:Child; D017097:Electric Impedance; D005260:Female; D005528:Foot; D006801:Humans; D009765:Obesity / Q000175:diagnosis* / Q000208:ethnology* / Q000503:physiopathology; D011237:Predictive Value of Tests; D012044:Regression Analysis; D015203:Reproducibility of Results; D013714:Tennessee; D001741:Black or African American