Fracture risk reduction with alendronate in women with osteoporosis: The Fracture Intervention Trial

We examined the effect of alendronate treatment for 3-4 yr on risk of new f racture among 3658 women with osteoporosis enrolled in the Fracture Interve ntion Trial. This cohort included women with existing vertebral fracture an d those with osteoporosis as defined by T score of less than -2.5 at the fe moral neck but without vertebral fracture. All analyses were prespecified i n the data analysis plan. The magnitudes of reduction of fracture incidence with alendronate were sim ilar in both groups. The two groups were, therefore, pooled to obtain a mor e precise estimate of the effect of alendronate on relative risk of fractur e (relative risk, 95% confidence interval): hip (0.47, 0.26-0.79), radiogra phic vertebral (0.52, 0.42-0.66), clinical vertebral (0.55, 0.36-0.82), and all clinical fractures (0.70, 0.59-0.82). Reductions in risk of clinical f racture were statistically significant by 12 months into the trial. We conclude that reductions in fracture risk during treatment with alendron ate are consistent in women with existing vertebral fractures and those wit hout such fractures but with bone mineral density in the osteoporotic range . Furthermore, reduction in risk is evident early in the course of treatmen t. This pooled analysis provides a more precise estimate of the antifractur e efficacy of alendronate in women with osteoporosis than that in prior rep orts.