In this study, in a subgroup analysis of osteoporotic women (37% of the total population who fulfilled the definition of osteoporosis given above) a significant difference was seen in the incidence of hip fractures (alendronate 1.0% versus placebo 2.2%, a reduction of 56%) and in the incidence of ≥ 1 vertebral fracture (2.9% versus 5.8%, a reduction of 50%).