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.