Comparison of bioelectrical impedance analysis, body mass index and waist circumference in evaluating growth and development of children

Abstract

Objective To compare body mass index(BMI), bioelectrical impedance analysis(BIA) and waist circumference(WC) for the assessment of the growth and development of the children, and to explore the accuracy of BIA and WC for the assessment of the growth and development of the children. Methods Children were surveyed in Department of Child Health Care of Nanjing Children's Hospital from Aug.2011 to Aug.2012.BIA was used to measure body fat, skeletal muscles and bone minerals of these children, and WC was measured by meterstick.According to BMI and body fat parameters, the study subjects were classified into lower weight, normal weight, overweight and obese groups.According to the WC, the subjects were divided into the normal group and the abnormal group. Results There were 2313 children in this survey, 1528 boys of them, median age 7.7 years old(ranged from 3.0 to 16.8 years old), and 785 girls of all the children, median age 7.2 years old(ranged from 3.0 to 17.5 years old). Bone mineral content of skeletal muscles increased with age in boys and girls(P<0.001). According to BMI, there were 484(20.9%) obese children and 266(11.5%) lower weight children; according to the BIA, there were 663(28.7%) obese children and 481(20.8%) lower weight children; according to the WC, there were 597(25.8%)abnormal children.The sensitivity and specificity of WC and BIA were both higher in the evaluation of overweight and obesity status.When overweight and obesity were analyzed by BIA as well as WC, girls showed a higher specificity, while the boys showed a higher sensitivity.The sensitivity of BMI was higher than BIA in evaluating weight loss. Conclusions BIA as a commonly used indicator is reliable for population census, and it is more desirable if the measurement of WC is done at the same time.The high sensitivity of BIA makes it more suitable for screening overweight and obesity of children. Key words: Bioelectrical impedance analysis; Body mass index; Waist circumference; Child