双能X射线吸收法(DXA)和空气置换体积描记术(ADP)是两种广泛使用的身体成分分析(BCA)方法。然而,对两种方法在中国人群中获得的BCA结果差异知之甚少。本研究旨在比较中国中青年成年人DXA和ADP的测量差异。并探讨这种差异的影响因素。
共纳入186名健康志愿者(51.1%为男性),年龄在18-56岁,体重指数(BMI)为15.9-35.9kg/m2。脂肪质量(FM),脂肪质量百分比(FMP),在1小时内通过DXA和ADP分析无脂质量(FFM)。
一般来说,DXA和ADP的所有BCA测量值高度相关(组内相关系数ICC>0.80,P<0.001),而两种方法之间存在差异(均P<0.001)。在人口层面,更高的体脂估计值(FM:男性1.8±3.1kg,女性2.2±2.4kg;FMP:男性2.4±4.2%,女性3.1±3.5%),DXA的FFM低于ADP(男性为-0.2±3.1kg,女性为-0.9±2.4kg)。此外,与ADP有关的FM和FMP的平均差异从体重不足组的阳性变为肥胖组的阴性,FFM反之亦然。在个人层面,在体重不足的受试者中,±15%以内的FM和FMP的相对误差比例小于10%,在肥胖受试者中超过75%.ForFFM,所有体重不足的受试者的相对误差在15%以内,肥胖男性占90.5%,肥胖女性占85.0%。
DXA和ADP的BCA结果高度相关,但两种方法之间的差异受到人群和个体BMI状况的强烈影响.在体重过轻和肥胖受试者中交换通过两种方法测量的体脂结果时应特别谨慎。
Dual-energy X-ray absorptiometry (DXA) and air displacement
plethysmography (ADP) are two widely used methods for body composition analysis (BCA). However, little is known about the discrepancies in the results of BCA obtained from the two methods in Chinese population. This study aimed to compare the measurement differences between DXA and ADP in young and middle-aged Chinese adults, and to explore the influential factors of this difference.
A total of 186 healthy volunteers (51.1% males) who aged 18-56 years old with body mass index (BMI) of 15.9-35.9 kg/m2 were enrolled. Fat mass (FM), fat mass percentage (FMP), and fat-free mass (FFM) were analyzed by both DXA and ADP within 1 h.
In general, all the BCA measures of DXA and ADP were highly correlated (intraclass correlation coefficient ICC>0.80, P < 0.001), while differences were found between the two methods (all P < 0.001). At the population level, greater body fat estimates (FM: 1.8 ± 3.1 kg in males and 2.2 ± 2.4 kg in females; FMP: 2.4 ± 4.2% in males and 3.1 ± 3.5% in females), whereas lower FFM (-0.2 ± 3.1 kg in males and -0.9 ± 2.4 kg in females) were found for DXA than ADP. Moreover, the average difference in FM and FMP as referred to ADP changed from positive in underweight group to negative in obesity group, and vice versa for FFM. At the individual level, the proportion of relative errors for FM and FMP within ±15% was less than 10% in underweight subjects and over 75% in those with obesity. For FFM, all underweight subjects had a relative error within 15%, and the proportion was 90.5% for obese males and 85.0% for obese females.
BCA results by DXA and ADP were highly correlated, but the differences between the two methods were strongly influenced by BMI status at both population and individual levels. Caution should be especially taken when interchanging body fat results measured by the two methods in underweight and obese subjects.