Faculty of Medicine, University of Manitoba, Winnipeg, Canada.
Department of Medicine, University of Manitoba, Winnipeg, Canada.
J Clin Densitom. 2014 Jan-Mar;17(1):54-9. doi: 10.1016/j.jocd.2013.01.007. Epub 2013 Mar 1.
Low body mass index is considered to be an important risk factor for fractures in postmenopausal women, in part reflecting its association with lower bone mineral density (BMD). In contrast, obesity is thought to be protective against fracture because of higher BMD and reduced transmitted force of falls as a result of soft tissue padding. Dual-energy X-ray absorptiometry (DXA) is most widely used for the assessment of osteoporosis. We hypothesized that trochanteric soft tissue thickness, as measured directly on whole-body DXA scans, could be estimated using the regional measures of anteroposterior tissue thickness from hip and spine DXA. We identified 376 adult patients who underwent DXA evaluation of the lumbar spine, hip, and whole body at the same visit. The population was randomly divided into 2 equal-sized subgroups, one used to derive prediction equations for trochanteric soft tissue thickness and the other for independent validation. Compared with the actual measurement from the whole-body scans in the validation cohort, the DXA-based estimate gave an unbiased prediction of trochanteric soft tissue thickness (adjusted R² was 0.60 with a standard error of the estimate of 1.35cm), which was significantly better than estimation obtained without DXA information (p < 0.001). Area under the curve discrimination for trochanteric soft tissue thickness in the lowest and highest tertiles was 0.901 (95% confidence interval: 0.849-0.953) and 0.859 (95% confidence interval: 0.805-0.915), respectively. Model-based prediction of trochanteric soft tissue thickness in the lowest and highest tertiles had sensitivities of 78.5% and 91.9% and specificities of 64.4% and 86.8%, respectively. We conclude that regional DXA scans of the spine and hip can be used to estimate the trochanteric soft tissue thickness.
低体重指数被认为是绝经后妇女骨折的一个重要危险因素，部分原因是其与较低的骨密度（BMD）有关。相比之下，肥胖被认为是对骨折有保护作用的，因为它的 BMD 较高，而且由于软组织缓冲，跌倒时传递的力减小。双能 X 射线吸收法（DXA）是最常用于评估骨质疏松症的方法。我们假设，通过全身 DXA 扫描直接测量的转子间软组织厚度，可以通过髋关节和脊柱 DXA 的前后组织厚度的区域测量来估计。我们确定了 376 名在同一就诊时接受腰椎、髋关节和全身 DXA 评估的成年患者。该人群被随机分为两组，一组用于推导转子间软组织厚度的预测方程，另一组用于独立验证。与验证队列中全身扫描的实际测量值相比，DXA 估计值对转子间软组织厚度进行了无偏预测（调整后的 R²为 0.60，估计的标准误差为 1.35cm），明显优于不使用 DXA 信息的估计值（p<0.001）。在最低和最高三分位的转子间软组织厚度的曲线下面积鉴别值分别为 0.901（95%置信区间：0.849-0.953）和 0.859（95%置信区间：0.805-0.915）。在最低和最高三分位的基于模型的转子间软组织厚度预测的敏感性分别为 78.5%和 91.9%，特异性分别为 64.4%和 86.8%。我们的结论是，脊柱和髋关节的区域 DXA 扫描可以用于估计转子间软组织厚度。
