Antiresorptive treatment of postmenopausal osteoporosis: review of randomized clinical studies and rationale for the Evista alendronate comparison (EVA) trial.

Standard pharmacological antiresorptive therapy for the prevention and/or treatment of postmenopausal osteoporosis now consists of four categories of drugs: estrogens, a selective estrogen receptor modulator (SERM), bisphosponates, and calcitonin. All of these drugs have been studied in randomized controlled trials, but meaningful comparisons of the efficacy of drugs have been difficult due to differences in baseline risks for fracture and differences in study design, including calcium and vitamin D supplementation, definition of fracture, and discontinuation rates. The current paper reviews results from pivotal studies of antiresorptive therapies with fracture as a primary endpoint, as well as head-to-head trials comparing these therapies using surrogate markers of fracture risk, and introduces the first head-to-head trial with fracture as a primary endpoint.