Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada.
Department of Behavioral Health and Nutrition, College of Health Sciences, University of Delaware, Newark, Delaware, USA.
Nutr Clin Pract. 2020 Dec;35(6):1029-1040. doi: 10.1002/ncp.10438. Epub 2019 Nov 25.
Bioelectrical impedance analysis (BIA) is commonly used to assess fat-free mass (FFM) and fat mass (FM) in breast cancer patients. However, because of the prevalence of overweight, obesity and variable hydration status in these patients, assumptions for existing prediction equations developed in healthy adults may be violated, resulting in inaccurate body composition assessment.
We measured whole-body FFM using single-frequency BIA (50 kHz) and dual-energy x-ray absorptiometry (DXA) in 48 patients undergoing treatment for breast cancer. We applied raw BIA data to 18 previously published FFM prediction equations (FFM ) and compared these estimates to DXA (FFM ; reference method).
On average, patients were 52 ± 10 (mean ± SD) years of age and overweight (body mass index: 27.5 ± 5.5 kg/m ; body fat by DXA: 40.1% ± 6.6%). Relative to DXA, BIA overestimated FFM by 4.1 ± 3.4 kg (FFM : 42.0 ± 5.9 kg; FFM : 46.1 ± 3.4 kg). Individual equation-generated predictions of FFM ranged from 39.6 ± 6.7 to 52.2 ± 5.6 kg, with 16 equations overestimating and 2 equations underestimating FFM compared with FFM . Based on equivalence testing, no equation-generated estimates were equivalent to DXA.
Compared with DXA, BIA overestimated FFM in breast cancer patients during treatment. Although several equations performed better than others, none produced values that aligned closely with DXA. Caution should be used when interpreting BIA measurements in this clinical population, and future studies should develop prediction equations specific to breast cancer patients.
生物电阻抗分析（BIA）常用于评估乳腺癌患者的去脂体重（FFM）和脂肪量（FM）。然而，由于这些患者超重、肥胖和体液状态变化的普遍性，对于在健康成年人中开发的现有预测方程的假设可能会被违反，从而导致身体成分评估不准确。
我们使用单频 BIA（50 kHz）和双能 X 射线吸收法（DXA）测量了 48 名正在接受乳腺癌治疗的患者的全身 FFM。我们将原始 BIA 数据应用于 18 个先前发表的 FFM 预测方程（FFM ），并将这些估计值与 DXA（FFM ；参考方法）进行比较。
平均而言，患者的年龄为 52 ± 10 岁（均值 ± 标准差），且超重（体重指数：27.5 ± 5.5 kg/m ；DXA 测量的体脂肪率：40.1% ± 6.6%）。与 DXA 相比，BIA 高估了 4.1 ± 3.4 kg 的 FFM（FFM ：42.0 ± 5.9 kg；FFM ：46.1 ± 3.4 kg）。个体方程生成的 FFM 预测值范围为 39.6 ± 6.7 至 52.2 ± 5.6 kg，其中 16 个方程高估了 FFM，2 个方程低估了 FFM ，与 FFM 相比。基于等效性检验，没有一个方程生成的估计值与 DXA 等效。
与 DXA 相比，BIA 在乳腺癌患者治疗期间高估了 FFM。尽管一些方程的表现优于其他方程，但没有一个方程生成的值与 DXA 紧密一致。在解释该临床人群的 BIA 测量值时应谨慎，未来的研究应针对乳腺癌患者开发特定的预测方程。
