J Acad Nutr Diet. 2018 Aug;118(8):1464-1473. doi: 10.1016/j.jand.2018.01.013. Epub 2018 Apr 12.
In individuals with bronchiectasis, fat-free mass depletion may be common despite a low prevalence of underweight and is considered a risk factor for increased morbidity and mortality. Techniques to adequately estimate fat-free mass and its changes over time are needed.
The purpose of this study was to assess agreement among values obtained with three different body composition techniques: skinfold thickness measurement (STM), bioelectrical impedance analysis (BIA), and dual-energy x-ray absorptiometry (DXA).
The study was a secondary analysis of data from a randomized controlled trial.
PARTICIPANTS/SETTING: A respiratory rehabilitation program was administered for 3 months to individuals with bronchiectasis from the bronchiectasis unit of the Regional University Hospital in Malaga, Spain, from September 2013 to September 2014. Individuals with a body mass index (calculated as kg/m) >18.5 who were aged 65 years or younger and those with a body mass index >20 who were older than 65 years were included.
At baseline and at 3 and 6 months, body composition was determined by DXA and STM.
Statistical concordance was assessed with the intraclass correlation coefficient (ICC), kappa coefficient, and the degree of agreement using the Bland Altman method. For comparison of the quantitative variables at baseline vs at 3 months and 6 months, the paired sample t test (or the Wilcoxon test) was used.
Thirty participants were included. Strong agreement was observed between body composition values determined by BIA and DXA in fat mass (ICC: 0.92) and fat-free mass (ICC: 0.87). Strong agreement was observed between STM and DXA in the values for fat-free mass (ICC: 0.91) and fat mass (ICC: 0.94), and lower agreement was observed for the longitudinal data and in the regional values. The mean difference between fat-free mass determined by BIA and DXA was + 4.7 with a standard deviation of 2.4 kg in favor of BIA. The mean difference between fat-free mass determined by STM and DXA was +2.3 with a standard deviation of 2.7 kg in favor of STM. Six individuals were classified as having a low fat-free mass index (20%) by DXA vs four by STM (13%; kappa: 0.76) and only two by BIA (6.6%; kappa: 0.44) compared with DXA.
Despite good statistical agreement among values obtained with DXA, STM, and BIA, the study findings indicate that STM and BIA, above all, tended to overestimate fat-free mass compared with DXA.
在支气管扩张症患者中，尽管体重不足的患病率较低，但仍普遍存在去脂体重消耗，且被认为是发病率和死亡率增加的危险因素。需要有技术来充分估计去脂体重及其随时间的变化。
本研究的目的是评估三种不同身体成分技术（皮褶厚度测量（STM）、生物电阻抗分析（BIA）和双能 X 射线吸收法（DXA））所获得的值之间的一致性。
该研究是一项随机对照试验的二次分析。
参与者/设置：2013 年 9 月至 2014 年 9 月，西班牙马拉加地区大学医院支气管扩张症科对支气管扩张症患者进行了为期 3 个月的呼吸康复计划。纳入的参与者包括 BMI（计算为 kg/m）>18.5 岁且年龄<65 岁的患者，以及 BMI>20 岁且年龄>65 岁的患者。
在基线时和 3 个月和 6 个月时，通过 DXA 和 STM 确定身体成分。
采用组内相关系数（ICC）、kappa 系数和 Bland-Altman 方法评估一致性，并对定量变量的基线值与 3 个月和 6 个月值进行比较，采用配对样本 t 检验（或 Wilcoxon 检验）。
共纳入 30 名参与者。BIA 和 DXA 检测的脂肪量（ICC：0.92）和去脂体重（ICC：0.87）之间存在较强的一致性。STM 和 DXA 检测的去脂体重（ICC：0.91）和脂肪量（ICC：0.94）之间存在较强的一致性，纵向数据和区域值的一致性较低。BIA 与 DXA 测定的去脂体重之间的平均差值为+4.7kg，标准差为 2.4kg，BIA 更优。STM 与 DXA 测定的去脂体重之间的平均差值为+2.3kg，标准差为 2.7kg，STM 更优。与 DXA 相比，6 名参与者（20%）被 DXA 归类为低去脂体重指数（20%），4 名参与者（13%）被 STM（13%）归类，6 名参与者（6.6%）被 BIA 归类（kappa：0.76），只有 2 名参与者（6.6%）被 BIA 归类（kappa：0.44）。
尽管 DXA、STM 和 BIA 所获得的值之间存在良好的统计学一致性，但研究结果表明，与 DXA 相比，STM 和 BIA 往往会高估去脂体重。
