Department of Environmental and Life Sciences, University of Cagliari, Cagliari, Italy.
PLoS One. 2013;8(3):e58533. doi: 10.1371/journal.pone.0058533. Epub 2013 Mar 6.
Bioelectrical impedance vector analysis (BIVA) is a technique for the assessment of hydration and nutritional status, used in the clinical practice. Specific BIVA is an analytical variant, recently proposed for the Italian elderly population, that adjusts bioelectrical values for body geometry.
Evaluating the accuracy of specific BIVA in the adult U.S. population, compared to the 'classic' BIVA procedure, using DXA as the reference technique, in order to obtain an interpretative model of body composition.
A cross-sectional sample of 1590 adult individuals (836 men and 754 women, 21-49 years old) derived from the NHANES 2003-2004 was considered. Classic and specific BIVA were applied. The sensitivity and specificity in recognizing individuals below the 5(th) and above the 95(th) percentiles of percent fat (FMDXA%) and extracellular/intracellular water (ECW/ICW) ratio were evaluated by receiver operating characteristic (ROC) curves. Classic and specific BIVA results were compared by a probit multiple-regression.
Specific BIVA was significantly more accurate than classic BIVA in evaluating FMDXA% (ROC areas: 0.84-0.92 and 0.49-0.61 respectively; p = 0.002). The evaluation of ECW/ICW was accurate (ROC areas between 0.83 and 0.96) and similarly performed by the two procedures (p = 0.829). The accuracy of specific BIVA was similar in the two sexes (p = 0.144) and in FMDXA% and ECW/ICW (p = 0.869).
Specific BIVA showed to be an accurate technique. The tolerance ellipses of specific BIVA can be used for evaluating FM% and ECW/ICW in the U.S. adult population.
生物电阻抗向量分析（BIVA）是一种评估水合和营养状况的技术，已在临床实践中得到应用。特定 BIVA 是一种分析变体，最近针对意大利老年人群提出，用于调整身体几何形状的生物电阻抗值。
使用 DXA 作为参考技术，评估特定 BIVA 在成年美国人群中的准确性，与“经典”BIVA 程序进行比较，以获得身体成分的解释模型。
本研究为一项横断面样本研究，共纳入 1590 名成年人（836 名男性和 754 名女性，年龄 21-49 岁），来自 2003-2004 年 NHANES 研究。应用经典和特定 BIVA。通过接受者操作特征（ROC）曲线评估脂肪百分比（FMDXA%）和细胞外/细胞内水（ECW/ICW）比值低于第 5 百分位数和高于第 95 百分位数的个体的敏感性和特异性。通过概率单位多重回归比较经典和特定 BIVA 的结果。
特定 BIVA 在评估 FMDXA%方面明显比经典 BIVA 更准确（ROC 曲线下面积分别为 0.84-0.92 和 0.49-0.61；p = 0.002）。ECW/ICW 的评估是准确的（ROC 曲线下面积在 0.83 到 0.96 之间），并且两种方法的表现相似（p = 0.829）。特定 BIVA 在两性之间（p = 0.144）和 FMDXA%和 ECW/ICW 方面的准确性相似（p = 0.869）。
特定 BIVA 是一种准确的技术。特定 BIVA 的耐受椭圆可用于评估美国成年人群的 FM%和 ECW/ICW。
