Phase angle and its determinants in healthy subjects: influence of body composition
Phase angle and its determinants in healthy subjects: influence of body composition
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DOI：
10.3945/ajcn.115.116772
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发表时间：
2016-03-01
影响因子：
7.1
通讯作者：
Heymsfield, Steven B.
中科院分区：
文献类型：
--
作者：
Gonzalez, Maria Cristina;Barbosa-Silva, Thiago G.;Heymsfield, Steven B.
背景：相位角（PA）已被用作几种临床情况下的预后指标。然而，它的生物学意义是不完全understood.Objective：我们验证了如何身体组成成分可以解释PA.Design：该试验是一项横断面研究，涉及1442名参与者（女性：58.5%;高加索人：40.2%）从身体组成的研究。氚标记稀释和全身钾分别用于估计全身水（TBW）和细胞内水（ICW）。细胞外水（ECW）和ECW：ICW比估计从这些值的差异和比率。采用双能X线吸收法、水下称重法和总体重法测定去脂体重（FFM）和脂肪量（FM）。使用单频生物电阻抗分析系统估计PA。PA和所有身体成分变量之间的相关性进行了评价。进行多元线性回归分析以调整身体成分变量对PA变异性的影响。所有的分析分别按性别进行。结果：与男性相比，女性表现出显着更大的ECW：ICW的比例和FM。最高的正相关性之间的PA和实况调查团获得使用UWW（男女）。两性的PA与ECW：ICW比率之间的负相关性最高。在多元线性回归模型中，年龄、种族、身高、ECW：ICW和UWW的FFM是PA的重要决定因素。即使调整了所有显著的协变量，解释的PA方差也很低（男性和女性的调整后R-2分别为0.539和0.421）。在男性和女性的总PA预测的影响最大的是年龄，FFM，和height.Conclusions：年龄是最重要的PA预测男性和女性其次是FFM和身高。ECW：ICW的贡献可以解释在临床环境中和肥胖人群中观察到的PA的相关性。
Background: The phase angle (PA) has been used as a prognostic marker in several clinical situations. Nevertheless, its biological meaning is not completely understood.Objective: We verified how body-composition components could explain the PA.Design: The trial was a cross-sectional study involving 1442 participants (women: 58.5%; Caucasian: 40.2%) from body-composition studies. Labeled tritium dilution and total-body potassium were used to estimate total-body water (TBW) and intracellular water (ICW), respectively. Extracellular water (ECW) and the ECW:ICW ratio were estimated from the difference and the ratio of these values. Fat-free mass (FFM) and fat mass (FM) were estimated with the use of dual-energy X-ray absorptiometry, underwater weighing (UWW), and TBW. The PA was estimated with the use of a single-frequency bioelectrical impedance analysis system. Correlations between the PA and all body-composition variables were evaluated. A multivariate linear regression analysis was performed to adjust for the effects of body-composition variables on the PA variability. All analyses were performed separately by sex.Results: Compared with men, women exhibited significantly larger ECW:ICW ratios and FM. The highest positive correlation was shown between the PA and FFM obtained with the use of UWW (both sexes). The highest negative correlation was shown between the PA and ECW: ICW ratios for both sexes. Age, race, height, ECW:ICW, and FFM from UWW were significant PA determinants in a multivariate linear regression model. Even after adjustment for all significant covariates, the explained PA variance was low (adjusted R-2 = 0.539 and 0.421 in men and women, respectively). The greatest impact on the total PA prediction in both men and women were age, FFM, and height.Conclusions: Age is the most significant PA predictor in men and women followed by FFM and height. The ECW:ICW contribution may explain the association of the PA observed in the clinical setting and in people who are obese.