Position Development Conference. (Special Article).

Bone densitometry is routinely used to assess the skeleton in patients who have diseases or conditions that can cause low bone mass. However, there are some areas of controversy related to the interpretation of bone densitometry results. To address these issues, the international Society for Clinical Densitometry (ISCD) convened a Position Development Conference in Denver, CO, July 20 through 22, 2001. The ISCD is a not-for-profit multidisciplinary society whose main mission is to promote quality in the performance and interpretation of bone densitometry examinations.

Methods

The Position Development Conference used an expert panel of physicians, researchers, and technologists, representing a wide array of specialty areas. (1) The purpose of the conference was to provide clinical recommendations based on scientific data and, if data were lacking, on expert opinion. Four general questions were selected for consideration by the panel on the basis of clinical importance and likelihood of reaching agreement:

1. Which central dual x-ray absorptiometry (DXA) skeletal sites and regions of interest should be used to determine the diagnosis of osteoporosis?

2. What are the criteria by which a densitometric diagnosis of osteoporosis can be made in men and non-Caucasian women?

3. What is the role of serial bone mineral density (BMD) measurements in patient management?

4. Can measurements of peripheral skeletal sites be used for diagnosis of osteoporosis?

Conference Conclusions

Diagnosis of Osteoporosis by Central DXA Skeletal Sites

When making a diagnosis of osteoporosis using DXA, BMD of both the PA spine and hip should be measured, and the site with lowest T score should be used to make the diagnosis. (2) BMD of the first four lumbar vertebrae should be measured whenever possible. Individual vertebrae should be excluded only if they are affected by localized structural change or artifact (eg, compression fracture, degenerative change). All manufacturers should use L1-L4 as the default region of interest (ROI) for their printouts. BMD of either hip may be measured. The lowest T score of four sites--PA spine, total hip, femoral neck, or trochanter--should be used for the diagnosis of osteoporosis. Ward's region and lateral spine should not be used. BMD of the forearm should be measured if the hip or spine BMD cannot be accurately measured.

Osteoporosis Diagnosis in Males and Non-Caucasians

At this time, there are insufficient data to definitively conclude that men and women fracture at the same DXA-measured BMD. (3) Therefore, a male normative database should continue to be used for central DXA diagnosis of osteoporosis in men. If, in the future, a female reference database becomes standard for osteoporosis diagnosis using T scores, the Z score should still be adjusted by sex. At this time, it is unclear if fractures occur at the same DXA-measured BMD in Caucasians and non-Caucasians. A uniform database (ie, that for Caucasians) should be used to calculate T scores for osteoporosis diagnosis in non-Caucasians. No consensus was reached on the use of ethnically adjusted Z scores. These recommendations are limited to the United States population.

Serial BMD Measurements in Patient Management

When monitoring patients using bone densitometry, the difference in BMD over time must exceed the least significant change (LSC) as determined by an in vivo precision study. (4) An in vivo precision study should be performed on individuals of similar age to the patient population using the method recommended by Bonnick et al, (5) 30 subjects measured twice or 15 subjects three times. The least significant change should be determined using a 95% confidence interval (LSC = precision error X 2.77). Subjects not on treatment can be monitored to determine if and when significant bone loss occurs. For patients undergoing therapy, the main objective of serial BMD measurements is to detect patients with significant loss of BMD despite treatment. When compared with the LSC, if the BMD increases or stays the same, no change in therapy is indicated. When there is a decrease in BMD (greater than the LSC), the clinician may consider changing therapy and/or evaluating for secondary causes of bone loss. Using DXA, the PA sp ine is the preferred site for monitoring. The total hip should be used when the PA spine is technically invalid. Except for patients with expected rapid bone loss (eg, glucocorticoid therapy), there is rarely an indication for repeating bone mass measurement in less than one year.

Peripheral Skeletal Site Measurements in Osteoporosis Diagnosis

The World Health Organization T score criteria for defining normal, osteopenia, and osteoporosis should not be used for peripheral devices. (6) No alternative to the use of WHO criteria has been established or accepted at this time. 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 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 wou ld be needed. There is no role for peripheral devices in the monitoring of patients on therapy.

Summary

In a series of three published articles, (1,4,6) the International Society for Clinical Densitometry has recorded the findings reached by an expert panel at the ISCD Position Development Conference held in July 2001. The key elements of those papers have been reviewed in this executive summary. It should be emphasized that the ISCD recommendations are not meant to serve as rigid guidelines or to replace clinical judgment. The recommendations will be reviewed and updated periodically as more data become available. A second Position Development Conference will be held in July 2003 in Cincinnati, OH. For information, visit the ISCD web site: http://www.iscd.org/

References

(1.) Leib ES, Lenchik L, Bilezikian JP, Maricic MJ, Watts NB. Position statements of the International Society for Clinical Densitometry: Methodology. J Clin Densitom 2002;5(Suppl):S5-S10.

(2.) Hamdy RC, Petak SM, Lenchik L; International Society for Clinical Densitometry Position Development Panel and Scientific Advisory Committee. Which central dual X-ray absorptiometry skeletal sites and regions of interest should be used to determine the diagnosis of osteoporosis? J Clin Densitom 2002;5(Suppl):S11-S18.

(3.) Binkley NC, Schmeer P, Wasnich RD, Lenchik L; International Society for Clinical Densitometry Position Development Panel and Scientific Advisory Committee, what are the criteria by which a densitometric diagnosis of osteoporosis can be made in males and non-Caucasians? J Clin Densitom 2002;5(Suppl):S19-S27.

(4.) Lenchik L, Kiebzak GM, Blunt BA; International Society for Clinical Densitometry Position Development Panel and Scientific Advisory Committee. What is the role of serial bone mineral density measurements in patient management? J Clin Densitom 2002;5(Suppl):S29-S38.

(5.) Bonnick SL, Johnston CC Jr, Kleerekoper M, Lindsay R, Miller P, Sherwood L, et al. Importance of precision in bone density measurements. J Clin Densitom 2001;4:105-110.

(6.) Miller PD, Njeh CF, Jankowski LG, Lenchik L; International Society for Clinical Densitometry Position Development Panel and Scientific Advisory Committee. What are the standards by which bone mass measurement at peripheral skeletal sites should be used in the diagnosis of osteoporosis? J Clin Densitom 2002;5(Suppl):S39-S45.

From the Division of Radiologic Sciences, Wake Forest University School of Medicine, Winston-Salem, NC, the Osteoporosis Center, Fletcher Allen Health Care, University of Vermont, Burlington, VT, the James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, the University of Wisconsin Hospital and Clinics, Madison, WI, the Colorado Center for Bone Research, Lakewood, CO, and the University of Cincinnati Osteoporosis Center, Cincinnati, OH.

This article is the position statement of the International Society for Clinical Densitometry Position Development Panel and Scientific Advisory Committee, It was originally presented at the International Society for Clinical Densitometry Position Development Conference, Denver, CO, July 20- 22, 2001.

Reprint requests to International Society for Clinical Densitometry, 342 N. Main Street, W. Hartford, CT 06117.

Copyright [C] 2003 by The Southern Medical Association

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