Post-Bisphosphonate DXA Monitoring Unrelated to Fracture Risk

Among women with osteoporosis randomized to discontinue bisphosphonates, results of bone mass testing in subsequent years were unrelated to future fracture risk. This undercuts guidelines and even a law.

Margaret L. Gourlay ML and Ensrud KE. Commentary: Bone Density and Bone Turnover Marker Monitoring After Discontinuation of Alendronate Therapy: An Evidence-Based Decision to Do Less. JAMA Intern Med. (2014) Published online May 5, 2014. doi:10.1001/jamainternmed.2014.162

Bauer DC, Schwartz A, Palermo L, et al.Fracture Prediction After Discontinuation of 4 to 5 Years of Alendronate Therapy: The FLEX Study. JAMA Intern Med. (2014). Published online May 05, 2014. doi:10.1001/jamainternmed.2014.1232

For women who discontinue alendronate therapy after taking it for four or five years, dual-energy x-ray absorptiometry (DXA) scans and bone turnover markers taken in subsequent years have no predictive value for fractures, and should not be used for monitoring, according to these authors.

However, lower hip DXA measured at time of discontinuation and older age were significantly related to increased fracture risk during the next five years.

This contradicts clinical practice guidelines, and the “Bone Mass Measurement Act,” which endorse more frequent testing.

Patients in the study are from FLEX, the long-term extension of the Fracture Intervention Trial (FIT) which randomized postmenopausal women with low femoral neck body mass density (BMD), with or without vertebral fracture, to alendronate or placebo, for up to 4.5 years. FLEX followed 1,099 participants for another five years with another randomized trial, which again divided participants into a placebo or alendronate group.

This present study follows up the 437 participants of FLEX who were assigned to placebo, 22% of whom experienced symptomatic fractures. The study found that, the years after discontinuation, DXA or bone turnover markers couldn’t predict who those 22% would be. However, older patients and those in the lowest third rank of hip DXA measures taken at the time of discontinuation were significantly more likely than others to have fractures.

How should these high-risk patients be managed? These authors have no evidence-based answer. Perhaps bisphosphonate tapering or intermittent dosing “can minimize immediate post-treatment fracture events,” the editorial suggests, but this is a question for future randomized trials.