Epidemiology of osteoporosis: predicting who is at risk.

A number of risk factors have been associated with osteoporosis, but few of them are particularly strong predictors of low bone mass or increased fracture incidence and the "best" set of variables changes from study to study. This does not provide adequate precision for classifying individual patients, and the focus of risk assessment, especially in perimenopausal women, has been on in vivo bone mass measurements. Prospective studies show that these values correspond to subsequent fracture incidence, and there is currently no alternative to bone mass measurements for stratifying patients by fracture risk. However, the level of risk at which treatment should be initiated for fracture prevention has not been agreed upon. Additional research is needed to refine risk factors for low bone mass and for falls and to design interventions to reduce the impact of osteoporosis in the population.