It has been shown that in subjects who were treatment-naïve or previously treated with alendronate, transitioning to denosumab treatment was associated with greater gains in BMD and decreases in bone turnover markers when compared with subjects continuing on alendronate treatment [9] and [10]. It is not known whether this observation would be similar with other bisphosphonates, which is an important consideration for women or their physicians who are considering a change in therapy due to unsatisfactory treatment effect. The purpose of this randomized, open-label trial was to compare the safety and efficacy of transitioning to denosumab or the bisphosphonate risedronate

for 12 months, in postmenopausal women who were previously treated with daily or weekly alendronate and were considered to be suboptimally see more adherent to their current therapy. This 12-month, multicenter, international (82 centers in Europe, Australia, and Canada), randomized, open-label, parallel-group study was conducted in postmenopausal women who had previously been prescribed alendronate therapy, but had either stopped taking alendronate or were currently taking alendronate, but demonstrated suboptimal adherence to treatment. Subjects were randomized 1:1 to receive either denosumab 60 mg subcutaneously (SC) every selleck chemicals 6 months (Q6M) or risedronate orally (PO) 150 mg once

monthly (QM, one 75 mg tablet on each of 2 consecutive days) for 12 months. The protocol specified that all subjects were required to take daily supplements of second ≥ 1000 mg elemental calcium and ≥ 800 IU vitamin D during the study. Ambulatory, postmenopausal women aged ≥ 55 years were eligible if they had been previously prescribed alendronate therapy, with the first daily or weekly alendronate prescription ≥ 1 month prior to screening, without limitation of alendronate treatment duration. All subjects provided signed informed consent prior to initiation of any study procedure. With a 1:1 randomization ratio, a sample size of 362 evaluable subjects in each treatment group would give > 90% power to detect a difference

> 1% at the total hip BMD at 12 months using a two-sided t-test at the 5% significance level, assuming a common standard deviation (SD) of 2.65%. Assuming a dropout rate of 10% in 12 months, the planned enrollment was 400 subjects in each treatment group, with a total sample size for the study of approximately 800 subjects. To be eligible to participate in this study, the subject must have either stopped oral alendronate therapy before the screening visit, or was still taking oral alendronate therapy (no washout period) with low adherence, which was assessed by a score of < 6 on the Osteoporosis Specific Morisky Medication Adherence Scale (OS-MMAS). The OS-MMAS is an osteoporosis-specific version of the MMAS, an 8-item questionnaire that has been evaluated for reliability and validity [11]. Each of the 8 items captures a specific medication-taking behavior.