Abstract：
OBJECTIVE: Equations estimating fat-free mass (FFM) in people living with the human immunodeficiency virus (HIV) show differences in the validation process. The current study aimed to verify the validity of FFM estimation equations derived from bioelectrical impedance (BIA) in people living with HIV aged 40 years and older.
METHODS: A cross-sectional study was conducted with 68 participants evaluated using dual-energy X-ray absorptiometry (DXA) and by two BIA devices (Analyzer and Biodynamics). The study aimed to determine the validity of six different FFM equations from four different studies by Lukaski and Bolonchuk (1987), Kotler et al. (1996), Beraldo et al. (2015) and Hegelund et al. (2017). Comparisons were made using the t-test or Wilcoxon test. To verify the validity between DXA and two BIA devices, the following statistical analyses were performed: Lin\'s concordance correlation coefficient, intraclass correlation coefficient, coefficient of determination, standard error of the estimate, differences in the limits of agreement by Bland and Altman analysis, correlation between the average and the differences of the methods by Pearson or Spearman correlation.
RESULTS: Only equation 2 of Kotler et al. (1996) for males by Biodynamics BIA showed no difference in FFM. The Lin\'s concordance correlation coefficient was excellent (0.96), irrespective of sex, for Equation 2 of Kotler et al. (1996) by BIA Analyzer. All equations were reproducible (>0.85). The coefficient of determination ranged from 68% to 92%, and the standard error of the estimates ranged from 1.8 kg to 5.0 kg. The differences between the limits of agreement ranged from 7.2 kg to 14.9 kg, and the correlations between the average and the differences of the methods showed differences in FFM for three equations (p < 0.01).
CONCLUSIONS: The choice of equations must consider the equipment used and the sex of the sample investigated. Only Equation 2 of Kotler et al. (1996) was considered valid, irrespective of sex, to estimate the FFM by BIA Analyzer.
METHODS: A cross-sectional study was conducted with 68 participants evaluated using dual-energy X-ray absorptiometry (DXA) and by two BIA devices (Analyzer and Biodynamics). The study aimed to determine the validity of six different FFM equations from four different studies by Lukaski and Bolonchuk (1987), Kotler et al. (1996), Beraldo et al. (2015) and Hegelund et al. (2017). Comparisons were made using the t-test or Wilcoxon test. To verify the validity between DXA and two BIA devices, the following statistical analyses were performed: Lin\'s concordance correlation coefficient, intraclass correlation coefficient, coefficient of determination, standard error of the estimate, differences in the limits of agreement by Bland and Altman analysis, correlation between the average and the differences of the methods by Pearson or Spearman correlation.
RESULTS: Only equation 2 of Kotler et al. (1996) for males by Biodynamics BIA showed no difference in FFM. The Lin\'s concordance correlation coefficient was excellent (0.96), irrespective of sex, for Equation 2 of Kotler et al. (1996) by BIA Analyzer. All equations were reproducible (>0.85). The coefficient of determination ranged from 68% to 92%, and the standard error of the estimates ranged from 1.8 kg to 5.0 kg. The differences between the limits of agreement ranged from 7.2 kg to 14.9 kg, and the correlations between the average and the differences of the methods showed differences in FFM for three equations (p < 0.01).
CONCLUSIONS: The choice of equations must consider the equipment used and the sex of the sample investigated. Only Equation 2 of Kotler et al. (1996) was considered valid, irrespective of sex, to estimate the FFM by BIA Analyzer.
摘要：
目的：估计患有人类免疫缺陷病毒（HIV）的人的无脂质量（FFM）的方程式显示验证过程中的差异。目前的研究旨在验证从生物电阻抗（BIA）得出的FFM估计方程在40岁及以上艾滋病毒感染者中的有效性。
方法：对68名参与者进行了横断面研究，这些参与者使用双能X射线吸收法（DXA）和两种BIA设备（分析仪和生物动力学）进行了评估。该研究旨在从Lukaski和Bolonchuk（1987）的四个不同研究中确定六个不同的FFM方程的有效性，Kotler等人。(1996),Beraldoetal.(2015)和Hegelund等人。(2017)。使用t检验或Wilcoxon检验进行比较。要验证DXA和两个BIA设备之间的有效性，进行了以下统计分析：Lin的一致性相关系数，组内相关系数，决定系数，估计的标准误差，通过Bland和Altman分析得出协议界限的差异，通过皮尔逊或斯皮尔曼相关方法的平均值和差异之间的相关性。
结果：只有Kotler等人的等式2。(1996)通过生物动力学BIA对男性显示FFM没有差异。林氏一致性相关系数为优(0.96)，不论性别,对于Kotler等人的方程2。(1996)BIAAnalyzer。所有方程都是可重现的(>0.85)。决定系数从68%到92%不等,估计值的标准误差范围为1.8kg至5.0kg。协议限值之间的差异范围从7.2公斤到14.9公斤，方法的平均值和差异之间的相关性显示三个方程的FFM差异（p<0.01）。
结论：方程式的选择必须考虑所使用的设备和所研究样品的性别。只有Kotler等人的方程式2。(1996)被认为是有效的，不论性别,通过BIA分析仪估算FFM。
方法：对68名参与者进行了横断面研究，这些参与者使用双能X射线吸收法（DXA）和两种BIA设备（分析仪和生物动力学）进行了评估。该研究旨在从Lukaski和Bolonchuk（1987）的四个不同研究中确定六个不同的FFM方程的有效性，Kotler等人。(1996),Beraldoetal.(2015)和Hegelund等人。(2017)。使用t检验或Wilcoxon检验进行比较。要验证DXA和两个BIA设备之间的有效性，进行了以下统计分析：Lin的一致性相关系数，组内相关系数，决定系数，估计的标准误差，通过Bland和Altman分析得出协议界限的差异，通过皮尔逊或斯皮尔曼相关方法的平均值和差异之间的相关性。
结果：只有Kotler等人的等式2。(1996)通过生物动力学BIA对男性显示FFM没有差异。林氏一致性相关系数为优(0.96)，不论性别,对于Kotler等人的方程2。(1996)BIAAnalyzer。所有方程都是可重现的(>0.85)。决定系数从68%到92%不等,估计值的标准误差范围为1.8kg至5.0kg。协议限值之间的差异范围从7.2公斤到14.9公斤，方法的平均值和差异之间的相关性显示三个方程的FFM差异（p<0.01）。
结论：方程式的选择必须考虑所使用的设备和所研究样品的性别。只有Kotler等人的方程式2。(1996)被认为是有效的，不论性别,通过BIA分析仪估算FFM。
