Blake G M, Fogelman I
Department of Nuclear Medicine, Guy's Hospital, St. Thomas Street, London SE1 9RT, United Kingdom.
J Clin Densitom. 2001 Summer;4(2):83-96. doi: 10.1385/jcd:4:2:083.
Over the past decade, bone density scans have assumed an essential role in the diagnosis of osteoporosis. Although dual X-ray absorptiometry (DXA) scans of the central skeleton remain widely used, a variety of different types of equipment for measuring peripheral sites is now available. However, the poor correlation between different types of measurement and a lack of consensus on how results from peripheral sites should be interpreted have proved a barrier to the more widespread use of these devices. These issues prompt the following questions: Which technique best identifies patients at risk of fracture? What approaches to scan interpretation ensure the closest agreement among different methods? Does it matter if different patients are selected for treatment on the basis of different techniques? The relative risk (RR)of fracture derived from prospective studies is a key parameter for comparing the clinical value of different techniques. Recent reports confirm the advantages of hip bone mineral density compared with peripheral measurements for predicting hip fracture risk, although for fractures at other sites the differences are inconclusive. Using receiver operating characteristic curves, we show that the guidelines adopted for scan interpretation are of crucial importance for ensuring that the information provided is used effectively. The closest agreement among different techniques is achieved by setting thresholds for peripheral devices that target either the same percentage of the population or the same percentage of future fracture cases as femur DXA. Different methods select different groups of individuals from the total pool of patients who will later sustain a fracture, with the most successful technique being the one with the largest RR value. The emphasis placed by many studies on validating new techniques by studying their correlation with DXA may lead to the clinical value of peripheral devices being underestimated when the key datum is the RR value inferred from prospective fracture studies.
在过去十年中，骨密度扫描在骨质疏松症的诊断中发挥了重要作用。虽然中央骨骼的双能X线吸收法（DXA）扫描仍被广泛使用，但现在有各种不同类型的设备可用于测量外周部位。然而，不同类型测量之间的相关性较差，以及对外周部位测量结果应如何解释缺乏共识，已证明是这些设备更广泛应用的障碍。这些问题引发了以下疑问：哪种技术能最好地识别骨折风险患者？扫描解读的哪些方法能确保不同方法之间的最大程度一致？基于不同技术选择不同患者进行治疗是否重要？前瞻性研究得出的骨折相对风险（RR）是比较不同技术临床价值的关键参数。近期报告证实，与外周测量相比，髋部骨密度在预测髋部骨折风险方面具有优势，尽管对于其他部位的骨折，差异尚无定论。通过绘制受试者工作特征曲线，我们表明采用的扫描解读指南对于确保有效利用所提供的信息至关重要。通过为外周设备设定阈值来实现不同技术之间的最大程度一致，这些阈值针对的是与股骨DXA相同比例的人群或相同比例的未来骨折病例。不同方法从最终会发生骨折的患者总群体中选择不同的个体组，最成功的技术是RR值最大的技术。许多研究通过研究新技术与DXA的相关性来验证新技术，这种做法可能导致在外周设备的关键数据是前瞻性骨折研究推断出的RR值时，其临床价值被低估。
