School of Dietetics and Human Nutrition, McGill University, Ste-Anne-de-Bellevue, Quebec, Canada.
Department of Pediatrics, McGill University, Montreal, Quebec, Canada; The Montreal Children's Hospital, Montreal, Quebec, Canada.
J Clin Densitom. 2013 Jul-Sep;16(3):302-307. doi: 10.1016/j.jocd.2012.07.005. Epub 2012 Aug 14.
Dual-energy X-ray absorptiometry (DXA) measures of bone mineral density (BMD) are generally not feasible in fieldwork. The present study determined the agreement between BMD measured by DXA and portable peripheral DXA in preschool aged children. Fifty-seven children (4.2 ± 1.0 yr) had their nondominant distal forearm scanned using a peripheral DXA scanner (PIXI; GE Medical Systems Lunar, Madison, WI) at their daycare and a DXA (4500A Discovery Series; Hologic Inc., Bedford, MA) at our research clinic. Correlation analysis, one-way analysis of variance, and Bland-Altman plots were performed to examine the agreement between measurements. Data were also divided into tertiles for cross-classification analysis and calculation of kappa coefficients. Distal forearm BMD measured by PIXI was significantly correlated with DXA measures of total forearm BMD (r > 0.51; p < 0.001), proximal 1/3 BMD (r > 0.41; p < 0.001), mid-BMD (r > 0.37; p < 0.001), and ultradistal (UD) BMD (r > 0.57; p < 0.001). Cross-classification in the same or adjacent tertile between measures (UD forearm: 96.5%; UD radius: 94.4%; total forearm: 87.7%; total radius: 84.2%) resulted in weighted kappa coefficients of 0.46, 0.58, 0.42, and 0.43, respectively. Bland-Altman plots further clarified these agreements as all had low bias (UD forearm: bias = 0.003 ± 0.002; UD radius: -0.015 ± 0.021; total forearm: -0.062 ± 0.027; total radius: -0.077 ± 0.026). These results demonstrate that portable DXA measures of forearm BMD agree moderately with DXA.
双能 X 射线吸收法（DXA）测量的骨密度（BMD）通常不适用于现场工作。本研究旨在确定在学龄前儿童中，DXA 与便携式外周 DXA 测量的 BMD 之间的一致性。57 名儿童（4.2±1.0 岁）在日托中心使用外周 DXA 扫描仪（PIXI；GE 医疗系统 Lunar，麦迪逊，威斯康星州）扫描其非优势的远端前臂，在我们的研究诊所使用 DXA（4500A Discovery 系列；Hologic Inc.，贝德福德，马萨诸塞州）。进行相关性分析、单向方差分析和 Bland-Altman 图，以检查测量值之间的一致性。还将数据分为三分位进行交叉分类分析和kappa 系数计算。PIXI 测量的远端前臂 BMD 与 DXA 测量的整个前臂 BMD（r>0.51;p<0.001）、近端 1/3 BMD（r>0.41;p<0.001）、中段 BMD（r>0.37;p<0.001）和超远端（UD）BMD（r>0.57;p<0.001）显著相关。测量值在同一或相邻三分位内的交叉分类（UD 前臂：96.5%；UD 桡骨：94.4%；整个前臂：87.7%；整个桡骨：84.2%）导致加权 kappa 系数分别为 0.46、0.58、0.42 和 0.43。Bland-Altman 图进一步阐明了这些一致性，因为所有图的偏差都很低（UD 前臂：偏差=0.003±0.002；UD 桡骨：-0.015±0.021；整个前臂：-0.062±0.027；整个桡骨：-0.077±0.026）。这些结果表明，便携式 DXA 测量的前臂 BMD 与 DXA 有中度的一致性。
