Based on available evidence, osteoporosis screening should take place at 15-year intervals for postmenopausal women who have normal bone density or mild osteopenia at their first assessment, at 5-year intervals for those who have moderate osteopenia, and at 1-year intervals for those who have advanced osteopenia, according to a report in the Jan. 19 New England Journal of Medicine.

Screening at shorter intervals is unlikely to improve prediction of the transition to osteoporosis, and thus won’t help clinicians judge when to start osteoporosis therapy so as to avert hip or vertebral fractures, said Dr. Margaret L. Gourlay of the department of family medicine, University of North Carolina, Chapel Hill, and her associates in the Study of Osteoporotic Fractures research group.

Current guidelines do not specify how long to wait between bone mineral density screening with dual-energy x-ray absorptiometry (DEXA), and no U.S. study to date "has addressed this clinical uncertainty," they noted.

"To determine how the BMD testing interval relates to the timing of the transition from normal [bone mineral density] or osteopenia to the development of osteoporosis before a hip or clinical vertebral fracture occurs, we conducted competing-risk analyses of data from 4,957 women, 67 years of age or older, who did not have osteoporosis at baseline and who were followed longitudinally for up to 15 years in the [Study of Osteoporotic Fractures]," the investigators said.

The appropriate screening interval was defined as the estimated time for 10% of the study subjects in each category of osteopenia severity to make the transition from normal BMD or osteopenia to osteoporosis before fractures occurred and before treatment for osteoporosis was initiated. The three categories of severity were normal BMD/mild osteopenia (T score of greater than -1.50) at the initial assessment, moderate osteopenia (T score of -1.50 to -1.99), and advanced osteopenia (T score of -2.00 to -2.49).

This interval was found to be 15 years for normal BMD/mild osteopenia, 5 years for moderate osteopenia, and 1 year for advanced osteopenia, Dr. Gourlay and her colleagues said (N. Engl. J. Med. 2012;366:225-33).

"Recent controversy over the harms of excessive screening for other chronic diseases reinforces the importance of developing a rational screening program for osteoporosis that is based on the best available evidence rather than on health care marketing, advocacy, and public beliefs that have encouraged overtesting and overtreatment in the U.S.," they noted.

"Our estimates for BMD testing proved to be robust after adjustment for major clinical risk factors" such as fracture history, smoking status, use of estrogen, and use of glucocorticoids. "However, clinicians may choose to reevaluate patients before our estimated screening intervals if there is evidence of decreased activity or mobility, weight loss, or other risk factors not considered in our analyses," they said.