Summary of meta-analyses of therapies for postmenopausal osteoporosis and the relationship between bone density and fractures.

We review the methodologic quality of the individual randomized trials and summarize the impact of different treatments on the risk of fractures and bone density. We present an estimate of the expected impact of anti-osteoporosis interventions on fracture incidence in prevention and treatment populations using numbers needed to treat. We also examine the relationship between changes in bone density and the relative risk reduction for vertebral and nonvertebral fractures using regression analyses drawn from the results of the systematic reviews.