Defer BMD testing intervals for older women, study suggests

Baseline T score is the most useful way to determine how often to test bone mineral density (BMD) in older postmenopausal women with normal BMD or osteopenia at initial assessment, according to a study published in the New England Journal of Medicine (2012;366[3]:225-233).

To investigate the relationship between interval of BMD testing and timing of transition from normal BMD or osteopenia to osteoporosis, researchers studied 4,957 women, 67 years of age or older, with normal BMD (T score at femoral neck and total hip −1.00 or higher) or osteopenia (T score −1.01 to −2.49) and no history of hip or clinical vertebral fracture or treatment for osteoporosis. They followed the women prospectively for up to 15 years. BMD testing interval was defined as the estimated time for 10% of women to develop osteoporosis before suffering a hip or clinical vertebral fracture (adjusted for estrogen use and clinical risk factors).

The study found that fewer than 10% of women with normal bone density or mild osteopenia would develop osteoporosis during rescreening intervals of approximately 15 years. Rescreening intervals were 5 years for women with moderate osteopenia and 1 year for women with advanced osteopenia.

 “If BMD testing is deferred for 15 years among women with T scores greater than −1.50, there is a low likelihood of a transition to osteoporosis during that period,” the authors write. Estimated time to osteoporosis decreased significantly with advancing age, supporting shorter testing intervals as women grow older-perhaps an interval of 3 years rather than 5 for women 85 years or older with moderate osteopenia, for example.

Although the estimated testing intervals remained “robust” after adjusting for major clinical risk factors for fracture, the authors write that “clinicians may choose to reevaluate patients before our estimated screening intervals if there is evidence of decreased activity or mobility, weight loss, or other factors not considered in our analyses.” Body mass index wouldn’t have changed the recommended intervals for each T-score range if the maximum testing interval for any woman was considered to be 10 years, they observe.

Current estrogen use was significantly associated with higher BMD and longer testing interval. Nevertheless, the authors recommend against altering the testing interval based on estrogen use because of the transient effect of estrogen on BMD.

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