Lundin Hans, Torabi Faramarz, Sääf Maria, Strender Lars-Erik, Nyren Sven, Johansson Sven-Erik, Salminen Helena
Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden.
Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden.
PLoS One. 2015 Sep 28;10(9):e0137535. doi: 10.1371/journal.pone.0137535. eCollection 2015.
Dual X-ray and Laser (DXL) adds a measure of the external thickness of the heel, measured by laser, to a conventional measurement of bone mineral density (BMD) of the calcaneus, using Dual energy X-ray Absorptiometry (DXA). The addition of heel thickness aims at a better separation of fatty tissue from bone than the standard method of DXA, which may mistake fatty tissue for bone and vice versa. The primary aim of this study was to evaluate whether DXL of the calcaneus can be used to assess the 10-year risk of fractures. Secondary aims were to compare the predictive ability of DXL with the two most established methods, Dual energy X-ray Absorptiometry (DXA) of the hip and spine and the WHO fracture risk assessment tool, FRAX. In 1999 a cohort of 388 elderly Swedish women (mean age 73.2 years) was examined with all three methods. Prospective fracture data was collected in 2010 from health care registers. One SD decrease in BMD of the heel resulted in an age-adjusted Hazard Ratio (HR) of 1.47 for a hip fracture (95% CI 1.09-1.98). Harrell's C is the Cox regression counterpart of the Area Under Curve (AUC) of the Receiver Operating Characteristic (ROC) as a measure of predictive accuracy. Harrell's C for BMD of the calcaneus was 0.65 for prediction of hip fractures. These results were not significantly different from those for BMD of the femoral neck or for FRAX. The HR for a hip fracture, for one SD decrease in BMD at the femoral neck, was 1.72 (95% CI 1.21-2.44. Harrell's C was 0.67 for BMD at the femoral neck and 0.59 for FRAX. We conclude that DXL of the calcaneus could be a useful tool for fracture risk assessments.
双能X线与激光（DXL）技术在使用双能X线吸收法（DXA）对跟骨骨密度（BMD）进行传统测量的基础上，增加了一项通过激光测量足跟外部厚度的指标。增加足跟厚度的目的是为了比DXA标准方法更好地将脂肪组织与骨骼区分开来，因为DXA标准方法可能会将脂肪组织误判为骨骼，反之亦然。本研究的主要目的是评估跟骨的DXL技术是否可用于评估10年骨折风险。次要目的是将DXL的预测能力与两种最成熟的方法进行比较，即髋部和脊柱的双能X线吸收法（DXA）以及世界卫生组织骨折风险评估工具FRAX。1999年，对388名瑞典老年女性（平均年龄73.2岁）使用这三种方法进行了检查。2010年从医疗保健登记处收集了前瞻性骨折数据。足跟骨密度每降低1个标准差，髋部骨折的年龄调整风险比（HR）为1.47（95%置信区间1.09 - 1.98）。哈雷尔C统计量是作为预测准确性度量的接受者操作特征（ROC）曲线下面积（AUC）的Cox回归对应指标。跟骨骨密度预测髋部骨折的哈雷尔C统计量为0.65。这些结果与股骨颈骨密度或FRAX的结果无显著差异。股骨颈骨密度每降低1个标准差，髋部骨折的HR为1.72（95%置信区间1.21 - 2.44）。股骨颈骨密度的哈雷尔C统计量为0.67，FRAX为0.59。我们得出结论，跟骨的DXL技术可能是一种用于骨折风险评估的有用工具。
