Wabitsch M, Braun U, Heinze E, Muche R, Mayer H, Teller W, Fusch C
Department of Pediatrics I, University of Ulm, Germany.
Am J Clin Nutr. 1996 Jul;64(1):1-6. doi: 10.1093/ajcn/64.1.1.
The aim of the present study was to develop an equation for the prediction of total body water (TBW) from bioelectrical impedance analysis (BIA) in obese children and adolescents before and after weight reduction. In 146 obese subjects with a mean age of 12.7 +/- 3.0 y (5.5-17.8 y), TBW was measured by using deuterium dilution as well as the resistance index (RI; ht2/resistance) using BIA before and after weight loss. Initially, the RI correlated well with measured TBW (r2 = 0.92, P < 0.001). A multiple-regression analysis using forward stepwise selection of the variables RI, sex, age, weight, height, and waist-hip ratio revealed that the equation TBW = 0.35 x RI + 0.27 x age + 0.14 x weight - 0.12 predicts most accurately individual values of TBW before weight loss (adjusted r2 = 0.96, SEE = 1.9 L) with a mean error of predicted TBW of 1.40 +/- 1.38 L. This equation was validated in 1000 random samples (bootstrap-sampling method), giving a mean r2 of 0.95. During the weight-reduction program, which included an energy-restricted diet and an extensive exercise program, the patients lost 7.7 +/- 3.2 kg, leading to a small decrease in TBW of 0.4 +/- 1.5 L. When the developed prediction equation was applied to the data after weight loss, an r2 value of 0.94 between measured and calculated TBW and a mean error of 2.18 +/- 1.89 L was obtained. Validation of the equation in 1000 random samples after weight loss again gave a mean r2 value of 0.95. Individual changes in predicted TBW correlated only weakly with those of measured TBW (r = 0.21, P < 0.05). Thus, individual TBW values before and after weight loss can be predicted by BIA with acceptable accuracy by using the developed equation. However, prediction of small individual changes in TBW during weight loss is not possible by BIA.
本研究的目的是建立一个方程，用于通过生物电阻抗分析（BIA）预测肥胖儿童和青少年在减肥前后的全身水含量（TBW）。在146名平均年龄为12.7±3.0岁（5.5 - 17.8岁）的肥胖受试者中，在减肥前后使用氘稀释法以及通过BIA测量电阻抗指数（RI；身高的平方/电阻）来测量TBW。最初，RI与测量的TBW相关性良好（r² = 0.92，P < 0.001）。使用变量RI、性别、年龄、体重、身高和腰臀比的向前逐步选择进行多元回归分析表明，方程TBW = 0.35×RI + 0.27×年龄 + 0.14×体重 - 0.12能够最准确地预测减肥前TBW的个体值（调整后r² = 0.96，标准估计误差SEE = 1.9 L），预测的TBW平均误差为1.40±1.38 L。该方程在1000个随机样本中（自助抽样法）得到验证，平均r²为0.95。在包括能量限制饮食和广泛运动计划的减肥计划期间，患者体重减轻了7.7±3.2 kg，导致TBW略有下降，为0.4±1.5 L。当将建立的预测方程应用于减肥后的数据时，测量的TBW与计算的TBW之间的r²值为0.94，平均误差为2.18±1.89 L。该方程在减肥后的1000个随机样本中再次得到验证，平均r²值为0.95。预测的TBW个体变化与测量的TBW个体变化仅具有较弱相关性（r = 0.21，P < 0.05）。因此，使用建立的方程通过BIA可以以可接受的准确性预测减肥前后的个体TBW值。然而，通过BIA无法预测减肥期间TBW的微小个体变化。
