Calcitonin versus etidronate for the treatment of postmenopausal osteoporosis: a meta-analysis of published clinical trials.

This review examines the evidence on the efficacy of calcitonin and etidronate in the prevention of osteoporosis and osteoporotic fractures. MEDLINE was searched for clinical trials calcitonin or etidronate and reviews of the treatment of postmenopausal osteoporosis. The reference sections of the papers retrieved were again searched for trials on the treatments of interest. Two people independently collected data from the trials that met the inclusion criteria of the study. Weighted means in the change in bone mineral density (BMD) and differences in vertebral fracture rates were computed for calcitonin and etidronate separately. The existence of publication bias was investigated by funnel plots of effect size against sample size. Eighteen clinical trials and calcitonin and six with etidronate were included in the meta-analysis. The pooled change in vertebral BMD at the end of the studies was 1.97 (95% CI 1.77 to 2.17) with calcitonin and 3.20 (95% CI 2.92 to 3.48) with etidronate. Pooled change in proximal femur BMD was 0.32 (95% CI -0.27 to 0.91) with calcitonin and 2.42 (95% CI 2.16 to 2.68) with etidronate. The aggregated number of vertebral fractures prevented by the treatment was 59.2 per 1000 patient-years (95% CI 55.1 to 63.3) for calcitonin and 28.3 (95% CI 26.2 to 30.4) for etidronate. With the available evidence we cannot establish the superiority of either of the two drugs for the treatment of postmenopausal osteoporosis. The clinical trials are particularly lacking in data on hip fracture, the most important consequence of osteoporosis. In this situation consideration of the relative costs of the drugs is prominent.