Comparison Between Bioelectrical Impedance Analysis and Dual Energy X-ray Absorptiometry in Obese Children's Body Composition Measurements

Objective To compare Bioelectrical Impedance Analysis(BIA) and Dual Energy X-ray Absorptiometry(DEXA) measurement in body composition of normal-weight children aged 7-15 years old,and to provide bases for the research of children' s body composition.Methods For each gender and age group from 7 to 15 years old,about 10 normal-weight children (180 totally) were selected to receive body composition measurement by both BIA and DEXA.Correlation and agreement of the two methods were analyzed.Results Most correlation coefficients of BIA and DEXA measurement in muscle,bone mineral content,fat and body fat percentage were statistically significant(P0.05).The correlation coefficients for female fat tissue and body fat percentage were higher than those of male.The difference in fat percentage between BIA and DEXA decreased with age,but the standard deviation of boy's increased with age while the girl's was comparatively stable.BlandAltman plot analysis showed that the agreement limit for body fat percentage between BIA and DEXA was from-7.6% to 12.6% and from-3.2% to 10.4% respectively.Fat-free mass indices obtained by BIA were higher than DEXA for both boys and girls and the differences were less than 2.0.Boy's differences in body fat percentage tended to increase with age and the difference of 20%-30% fat percentage group was the least for girl.Conclusion The correlation between BIA and DEXA in body composition measurement is good for children aged 7-15 years old.BIA will underestimate the fat mass and body fat percentage and overestimate muscle mass and bone mineral content.