Kolta S, Ravaud P, Fechtenbaum J, Dougados M, Roux C
Centre d'Evaluation des Maladies Osseuses, Cochin Hospital, René Descartes University, Paris, France.
Osteoporos Int. 1999;10(1):14-9. doi: 10.1007/s001980050188.
Dual-energy absorptiometry (DXA) is widely used for bone mineral density measurements. Different types of devices are available. Differences between devices from either the same manufacturer or different manufacturers can lead to difficulties in clinical practice when patients are followed on different machines. We calculated the accuracy and precision of 62 DXA devices from two manufacturers (51 Hologic, 11 Lunar) using a European Spine Phantom (ESP, semi-anthropomorphic). The ESP was measured 5 times on each device without repositioning. Accuracy was assessed by comparing bone mineral density (BMD, g/cm(2)) values measured on each device with the actual value of the phantom. Precision was assessed by the coefficient of variation (CVsd), using the root mean square average. The limits of agreement were estimated from the differences between each replicate measurement of BMD and the estimated true value for a particular manufacturer, according to Bland and Altman. The results confirm the difference between devices from different manufacturers (18.5%). Mean CVsd values were 0.57% and 0.64% for Hologic and Lunar respectively. The limits of agreement among devices from the same manufacturer were 0.026 g/cm(2) and 0.025 g/cm(2) for Hologic and Lunar respectively. Differences in extreme results between devices from the same manufacturer were on average 5.4% and 3.6% for Hologic and Lunar respectively. Results of different devices from the same manufacturer are highly comparable, although unpredictable differences exist that may be clinically relevant.
双能X线吸收法（DXA）广泛用于骨密度测量。有不同类型的设备可供使用。当在不同机器上对患者进行随访时，同一制造商或不同制造商的设备之间的差异可能会给临床实践带来困难。我们使用欧洲脊柱体模（ESP，半人体模型）计算了来自两家制造商的62台DXA设备（51台Hologic，11台Lunar）的准确性和精密度。在每台设备上对ESP进行5次测量，无需重新定位。通过将每台设备测量的骨密度（BMD，g/cm²）值与体模的实际值进行比较来评估准确性。使用均方根平均值，通过变异系数（CVsd）评估精密度。根据Bland和Altman方法，从BMD的每次重复测量值与特定制造商的估计真实值之间的差异估计一致性界限。结果证实了不同制造商设备之间的差异（18.5%）。Hologic和Lunar设备的平均CVsd值分别为0.57%和0.64%。同一制造商设备之间的一致性界限，Hologic和Lunar分别为0.026 g/cm²和0.025 g/cm²。同一制造商不同设备的极端结果差异，Hologic和Lunar平均分别为5.4%和3.6%。同一制造商不同设备的结果具有高度可比性，尽管存在可能具有临床相关性的不可预测差异。
