Department of Chemical and Biological Sciences, University of Sonora, Hermosillo, Sonora, Mexico.
Coordinación de Nutrición, Centro de Investigación en Alimentación y Desarrollo, A.C. Hermosillo, Sonora, Mexico.
J Nutr. 2023 Feb;153(2):443-450. doi: 10.1016/j.tjnut.2022.12.011. Epub 2022 Dec 28.
The medical body composition analyzer (mBCA) incorporates advances in multifrequency technology and has been validated using a 4-compartment (4C) model in adults but not in youths aged <18 y.
This study aimed to formulate a 4C model based on 3 reference methods and develop and validate a body composition prediction equation for the mBCA in youths aged 10‒17 y.
The body density of 60 female and male youths was measured by air displacement plethysmography, total body water by deuterium oxide dilution, and BMC by DXA. Data from the equation group (n = 30) were used to formulate a 4C model. The all-possible-regressions method was used to select variables. The model was validated in a second cohort (n = 30) in a random split design. The accuracy, precision, and potential bias were evaluated by the Bland and Altman procedure.
Mean age, weight (W), height (H), waist circumference, and z-score of BMI were 13.6 ± 2.3 y, 54.5 ± 15.5 kg, 156 ± 11.9 cm, 75.5 ± 10.9 cm, and 0.70 ± 1.32 z, respectively. The prediction equation was as follows: FFM in kg (FFM) = ([0.2081] ∗ [W] + [0.8814] ∗ [H/R] + [0.2055 ∗ Xc])-15.343; R = 0.96; standardized root-mean-square error (SRMSE) = 2.18 kg. FFM did not differ between the 4C method (38.9 ± 12.0 kg) and the mBCA (38.4 ± 11.4 kg) (P > 0.05). The relationship between these 2 variables did not deviate from the identity line, was not significantly different from 0, and the slope was not significantly different from 1.0. In the precision prediction model of mBCA, the R value was 0.98 and SRMSE was 2.1. No significant bias was found when regressing differences between methods and their means (P = 0.08).
The equation for the mBCA was accurate, precise, had no significant bias, had substantial strength of agreement and could be used in this age group when subjects were preferentially within the constraints of a specified body size.
医学体成分分析仪（mBCA）结合了多频技术的进步，并已通过 4 compartment（4C）模型在成年人中得到验证，但尚未在<18 岁的青少年中进行验证。
本研究旨在基于 3 种参考方法制定 4C 模型，并开发和验证适用于 10-17 岁青少年 mBCA 的体成分预测方程。
通过空气置换体描记法测量 60 名女性和男性青少年的体密度，通过重水稀释法测量全身水，通过 DXA 测量 BMC。从方程组（n=30）的数据中制定 4C 模型。采用全可能回归法选择变量。该模型在随机分组设计的第二队列（n=30）中进行验证。通过 Bland 和 Altman 程序评估准确性、精密度和潜在偏差。
平均年龄、体重（W）、身高（H）、腰围和 BMI 的 z 分数分别为 13.6±2.3 岁、54.5±15.5kg、156±11.9cm、75.5±10.9cm 和 0.70±1.32z。预测方程如下：kg 瘦体重（FFM）=（[0.2081]×[W]+[0.8814]×[H/R]+[0.2055×Xc]）-15.343；R=0.96；标准化均方根误差（SRMSE）=2.18kg。4C 方法（38.9±12.0kg）和 mBCA（38.4±11.4kg）之间的 FFM 无差异（P＞0.05）。这两个变量之间的关系没有偏离身份线，与 0 没有显著差异，斜率与 1.0 没有显著差异。在 mBCA 的精度预测模型中，R 值为 0.98，SRMSE 为 2.1。当回归方法之间的差异及其平均值时，没有发现显著的偏差（P=0.08）。
mBCA 方程准确、精确、无显著偏差，具有较强的一致性，当受试者优先在特定的体型范围内时，可用于该年龄组。
