Wan Ching S, Ward Leigh C, Halim Jocelyn, Gow Megan L, Ho Mandy, Briody Julie N, Leung Kelvin, Cowell Chris T, Garnett Sarah P
Institute of Endocrinology & Diabetes, The Children's Hospital at Westmead, Locked Bag 4001, Westmead NSW2145, Australia.
BMC Pediatr. 2014 Oct 3;14:249. doi: 10.1186/1471-2431-14-249.
There is a need for a practical, inexpensive method to assess body composition in obese adolescents. This study aimed to 1) compare body composition parameters estimated by a stand-on, multi-frequency bioelectrical impendence (BIA) device, using a) the manufacturers' equations, and b) published and derived equations with body composition measured by dual-energy x-ray absorptiometry (DXA) and 2) assess percentage body fat (%BF) change after a weight loss intervention.
Participants were 66 obese adolescents, mean age (SD) 12.9 (2.0) years. Body composition was measured by Tanita BIA MC-180MA (Tanita BIA8) and DXA (GE-Lunar Prodigy). BIA resistance and reactance data at frequencies of 5, 50, 250 and 500 kHz, were used in published equations, and to generate a new prediction equation for fat-free mass (FFM) using a split-sample method. Approximately half (n = 34) of the adolescents had their body composition measured by DXA and BIA on two occasions, three to nine months apart.
The correlations between FFM (kg), fat mass (kg) and %BF measured by BIA and DXA were 0.92, 0.93 and 0.78, respectively. The Tanita BIA8 manufacturers equations significantly (P < 0.001) overestimated FFM (4.3 kg [-5.3 to 13.9]) and underestimated %BF (-5.0% [-15 to 5.0]) compared to DXA. The mean differences between BIA derived equations and DXA measured body composition parameters were small (0.4 to 2.1%), not significant, but had large limits of agreements (~ ±15% for FFM). After the intervention mean %BF loss was similar by both methods (~1.5%), but with wide limits of agreement.
The Tanita BIA8 could be a valuable clinical tool to measure body composition at the group level, but is inaccurate for the individual obese adolescent.
需要一种实用且经济的方法来评估肥胖青少年的身体成分。本研究旨在：1）比较通过站立式多频生物电阻抗（BIA）设备使用以下两种方法估算的身体成分参数：a）制造商的公式，以及b）已发表和推导的公式与通过双能X线吸收法（DXA）测量的身体成分；2）评估体重减轻干预后体脂百分比（%BF）的变化。
参与者为66名肥胖青少年，平均年龄（标准差）12.9（2.0）岁。使用Tanita BIA MC - 180MA（Tanita BIA8）和DXA（GE - Lunar Prodigy）测量身体成分。在已发表的公式中使用了5、50、250和500 kHz频率下的BIA电阻和电抗数据，并使用拆分样本法生成了无脂肪质量（FFM）的新预测方程。大约一半（n = 34）的青少年在相隔三到九个月的时间里通过DXA和BIA进行了两次身体成分测量。
通过BIA和DXA测量的FFM（kg）、脂肪量（kg）和%BF之间的相关性分别为0.92、0.93和0.78。与DXA相比，Tanita BIA8制造商的公式显著（P < 0.001）高估了FFM（4.3 kg [-5.3至13.9]）并低估了%BF（-5.0% [-15至5.0]）。BIA推导公式与DXA测量的身体成分参数之间的平均差异较小（0.4至2.1%），无统计学意义，但一致性界限较大（FFM约为±15%）。干预后，两种方法的平均%BF损失相似（约1.5%），但一致性界限较宽。
Tanita BIA8在群体水平上可能是测量身体成分的有价值的临床工具，但对于个体肥胖青少年不准确。
