Rangel Peniche Diana Beatriz, Raya Giorguli Graciela, Alemán-Mateo Heliodoro
Universidad Autónoma de Querétaro, Facultad de Ciencias Naturales, Licenciatura y Maestría en Nutrición, Campus Juriquilla, Boulevard de las Ciencias S/N, CP 76230 Querétaro, Mexico.
Universidad Autónoma de Querétaro, Facultad de Ciencias Naturales, Licenciatura y Maestría en Nutrición, Campus Juriquilla, Boulevard de las Ciencias S/N, CP 76230 Querétaro, Mexico.
Arch Gerontol Geriatr. 2015 Jul-Aug;61(1):39-43. doi: 10.1016/j.archger.2015.03.007. Epub 2015 Apr 1.
To design and validate a predictive BIA equation to estimate ASM in a sample of non-Caucasian older people and to explore the accuracy of two previous single-frequency BIA published equations.
This is a cross-sectional study in 213 physically-independent and apparently healthy older men and women subjects from a central region of Mexico. Dual-energy X-ray absorptiometry, anthropometry, resistance, reactance, and other independent predictive variables were assessed. The total sample was randomized and split into two sub-samples: one group for the development of the predictive single-frequency BIA equation and the other for its validation. The equation was derived by step-wise regression, the goodness of fit was assessed by the highest determination coefficient (R(2)) and precision by the lowest root mean square error. In the validation sample, the accuracy of the new and the published BIA equations was tested by pure error. In addition, Bland and Altman analysis tested the bias.
The selected model had a R(2) of 0.91 and a RMSE of 1.01 kg and fulfilled every regression assumption. The predictive variables included were: Ht(2)/R, sex, and body weight. The new BIA equation showed a PE close to RMSE of the estimate with no significant bias. The published BIA equations proved to be inaccurate and had significant bias.
This new single-frequency BIA-derived equation was precise, accurate and free of bias. Published BIA equations to estimate ASM should not be used indistinctly in other ethnic groups without validation.
设计并验证一个预测性生物电阻抗分析（BIA）方程，以估计非白种老年人群样本中的去脂体重（ASM），并探讨之前发表的两个单频BIA方程的准确性。
这是一项针对来自墨西哥中部地区213名身体独立且明显健康的老年男性和女性受试者的横断面研究。评估了双能X线吸收法、人体测量学、电阻、电抗及其他独立预测变量。将总样本随机分为两个子样本：一组用于建立预测性单频BIA方程，另一组用于验证该方程。通过逐步回归推导方程，用最高决定系数（R²）评估拟合优度，用最低均方根误差评估精度。在验证样本中，通过纯误差检验新的和已发表的BIA方程的准确性。此外，采用Bland和Altman分析检验偏差。
所选模型的R²为0.91，均方根误差为1.01 kg，满足所有回归假设。纳入的预测变量包括：身高²/电阻、性别和体重。新的BIA方程显示预测误差接近估计值的均方根误差，且无显著偏差。已发表的BIA方程被证明不准确且存在显著偏差。
这个新的单频BIA衍生方程精确、准确且无偏差。在未经验证的情况下，已发表的用于估计ASM的BIA方程不应在其他种族群体中随意使用。
