We read with great interest the article by van Staa and coworkers on the bone mineral density (BMD) threshold for prediction of vertebral fractures in patients receiving oral glucocorticoid therapy (1). Compared with non–glucocorticoid users, glucocorticoid users appear to develop fractures at a higher BMD. The American College of Rheumatology recommends therapeutic intervention if the T score for BMD is below −1 in a patient who has had long-term treatment with glucocorticoids (2). The UK National Osteoporosis Society advocates intervention at a T score threshold of −1.5 (3). With the increasing use of bone density testing for diagnosing osteoporosis and establishing fracture risk, inconsistencies have arisen in the way in which bone densitometry is performed and the results interpreted. As an example, T score diagnostic thresholds for postmenopausal Caucasian women not exposed to glucocorticoids may not apply to patients who are receiving glucocorticoid therapy. A similar analogy could be made in applying World Health Organization T score criteria to men and premenopausal women.
To reduce these inconsistencies and improve interpretation and reporting of BMD, the International Society for Clinical Densitometry (ISCD) periodically convenes Position Development Conferences (PDCs). The most recent PDC was held in Cincinnati, Ohio, in July 2003. The ISCD is a not-for-profit multidisciplinary professional society with a mission to enhance knowledge and quality of bone densitometry among health care professionals. In addition, it provides continuing education courses for clinicians and technicians, and it supports clinical and scientific advances in the field.
The decision on whether to initiate therapeutic intervention must be made on the basis of knowledge of the individual patient and his/her associated risk factors, not on the basis of a numerical score. However, one of the goals of a professional society is to standardize the understanding of the field as much as possible based on evidence, as exemplified in the report by van Staa et al.
The ISCD recommends BMD testing in the following individuals: 1) women age 65 and older; 2) postmenopausal women under age 65 with risk factors; 3) men age 70 and older; 4) adults with a fragility fracture; 5) adults with a disease or condition associated with low bone mass or bone loss; 6) adults taking medications associated with low bone mass or bone loss; 7) anyone being considered for pharmacologic therapy; 8) anyone being treated, to monitor treatment effect; and 9) anyone not receiving therapy in whom evidence of bone loss would lead to treatment.
A complete review of all ISCD official positions is published in the Journal of Clinical Densitometry (4). A summary of the ISCD official positions is available online at the ISCD Web site (www.iscd.org), where there is also a viewable and downloadable slide presentation of the positions.