Treatment holidays in patients with postmenopausal osteoporosis: whom and when?

The controversy about the ideal duration of treatment with bisphosphonates is not new. As early as in 2005, some experts suggested that treatment with alendronate for patients with postmenopausal osteoporosis could be discontinued after five years, provided no fractures had occurred during this period and bone mass had improved as compared to baseline. This recommendation was based on the lack of data showing an additional fracture rate reduction when treatment was continued beyond five years, and on the fact that remodeling markers continued to be suppressed despite treatment discontinuation, which suggested a residual effect. The final data of the FLEX study were reported in 2006. In this study, 1099 women from the Fracture Intervention Trial (conducted to assess the anti-fracture efficacy of alendronate) were randomized again to three treatment arms: placebo, alendronate 5 mg/day, and alendronate 10 mg/day, for five years. In the placebo group, a decrease in bone mineral density (BMD) associated with increased remodeling was seen, but values prior to the start of treatment were not reached. The patients who continued to receive alendronate had a lower risk of clinical vertebral fractures as compared to the placebo patients, but no differences