The Official Positions of the International Society for Clinical Densitometry: acquisition of dual-energy X-ray absorptiometry body composition and considerations regarding analysis and repeatability of measures.

In preparation for the International Society for Clinical Densitometry Position Development Conference of 2013 in Tampa, Florida, Task Force 2 was created as 1 of 3 task forces in the area of body composition assessment by dual-energy X-ray absorptiometry (DXA). The assignment was to review the literature, summarize the relevant findings, and formulate positions covering (1) accuracy and precision assessment, (2) acquisition of DXA body composition measures in patients, and (3) considerations regarding analysis and repeatability of measures. There were 6 primary questions proposed to the task force by the International Society for Clinical Densitometry board and expert panel. Based on a series of systematic reviews, 14 new positions were developed, which are intended to augment and define good clinical practice in quantitative assessment of body composition by DXA.

What are the standards by which bone mass measurement at peripheral skeletal sites should be used in the diagnosis of osteoporosis?

Measurement of bone mineral density (BMD) at central skeletal sites with dual X-ray absorptiometry is the "gold standard" both for the diagnosis of osteoporosis using the criteria of the World Health Organization (WHO) and for monitoring individuals receiving antiresorptive treatment for osteoporosis. Measurement of BMD at peripheral sites (peripheral BMD) can be used to assess fracture risk, but application of the WHO criteria gives different prevalence values for "osteoporosis" with peripheral devices, and different risks for fracture at the same cut points. The International Society for Clinical Densitometry Position Development Conference panelists reached the following conclusions about peripheral BMD testing: First, WHO T-score criteria should not be used with peripheral devices. Second, for the identification of a level for peripheral BMD measurements above which osteoporosis is unlikely, device-specific cut points for peripheral BMD should be identified that have 90% sensitivity for identifying patients who have osteoporosis (T-score of -2.5 or below) based on measurements of the spine and hip. If central BMD testing is available, patients who have peripheral BMD below the 90% sensitivity level should have a central BMD measurement. If central BMD testing is not available, peripheral BMD might be used for identification of patients who are likely to have osteoporosis. Risk-based cut points were preferred to prevalence based cut points, and, again, device-specific cut points are needed. For patients tested only with a peripheral BMD device whose result is intermediate, clinical judgment would be needed. Third, peripheral BMD testing should not be used for monitoring patients who are taking antiresorptive therapy for osteoporosis. Fourth, peripheral BMD testing performs best when used for postmenopausal women. Further research on all these issues is needed.