Indices of changes in adiposity in American Indian children

Background. Pathways, a randomized trial, evaluated the effectiveness of a school-based obesity prevention program on body composition changes in American Indian children. Several body composition methods were compared in intervention and control schools for assessing body composition changes. Methods. Body composition methods, including skinfolds, bioelectric impedance analysis (BIA), body mass index (BMI), and using a combination of body composition methods were selected to assess 3-year changes in PBF in 705 children within 21 intervention schools and 663 children within 20 control schools. The study equation using skinfolds, BIA, and BMI was developed on a previous sample of American Indian children using deuterium oxide dilution as the criterion method. Results. Body fat changes among methods for the intervention sample ranged from 5.4% (BMI method) to 7.1% (combination of methods) and for the control sample, from 5.8% (BMI method) to 7.3% (combination of methods). The study equation estimates were significantly higher than the other methods and the BMI equation estimates were significantly lower than the other methods except by BIA. The BIA equation showed a significantly larger standard deviation of the difference over the 3-year intervention than each of the other methods indicating less reliability for detecting body composition changes. Conclusions. Within the Pathways large scale intervention trial with American Indian children, we found comparable yet significantly different mean PBF changes among methods. However, BIA was not as reliable as skinfolds and the combination of BIA, skinfolds, and body weight in assessing PBF changes.