Alendronate Once Weekly for the Prevention and Treatment of Bone Loss in Canadian Adult Cystic Fibrosis Patients (CFOS Trial)

Background Patients with cystic fibrosis (CF) are at risk for early bone loss, and demonstrate increased risks for vertebral fractures and kyphosis. A multicenter, randomized, controlled trial was conducted to assess the efficacy, tolerability, and safety of therapy with oral alendronate (FOSAMAX; Merck; Whitehouse Station, NJ) in adults with CF and low bone mass. Methods Participants received placebo or alendronate, 70 mg once weekly, for 12 months. All participants received 800 IU of vitamin D and 1,000 mg of calcium daily. Adults with confirmed CF with a bone mineral density (BMD) T score of < − 1.0 were eligible for inclusion. Participants who had undergone organ transplantation or had other reported contraindications were excluded from the study. The primary outcome measure was the mean (± SD) percentage change in lumbar spine BMD after 12 months. Secondary measures included the percentage change in total hip BMD, the number of new vertebral fractures (grade 1 or 2), and changes in quality of life. Results A total of 56 participants were enrolled in the study (mean age, 29.1 ± 8.78 years; 61% male). The absolute percentage changes in lumbar spine and total hip BMDs at follow-up were significantly higher in the alendronate therapy group (5.20 ± 3.67% and 2.14 ± 3.32%, respectively) than those in the control group (− 0.08 ± 3.93% and − 1.3 ± 2.70%, respectively; p < 0.001). At follow-up, two participants (both in the control group) had a new vertebral fracture (not significant), and there were no differences in quality of life or the number of adverse events (including serious and GI-related events). Conclusion Alendronate therapy was well tolerated and produced a significantly greater increase in BMD over 12 months compared with placebo. Trial registration ClinicalTrials.gov Identifier: NCT00157690