Risedronate prevents new vertebral fractures in postmenopausal women at high risk.

Independent risk factors for fracture include advanced age, preexisting fractures, and low bone mineral density. Rised-ronate has been shown in several large trials to be safe and effective for patients with osteoporosis, but its effects in populations at high risk are not well characterized. To determine the effect of risedronate on vertebral fracture in high-risk subjects, we pooled data from two randomized, double-blind studies [Vertebral Efficacy with Risedronate Therapy (VERT) Multinational (VERT-MN) and VERT-North America (VERT-NA)] in 3684 postmenopausal osteoporotic women treated with placebo or risedronate 2.5 or 5 mg/d and analyzed fracture risk in subgroups of subjects at high risk for fracture due to greater age or more prevalent fractures (vs. median for overall study population), or lower bone mineral density (T-score, -2.5 or less). Fractures were diagnosed by quantitative and semiquantitative assessment of radiographs at baseline and 1 yr. In the overall population, treatment for 1 yr with risedronate 5 mg/d reduced the risk of new vertebral fractures by 62% vs. control (relative risk, 0.38; 95% confidence interval, 0.25, 0.56; P < 0.001) and of multiple new vertebral fractures by 90% vs. control (relative risk, 0.10; 95% confidence interval, 0.04, 0.26; P < 0.001). Consistent risk reductions were observed at 1 yr in the risedronate-treated high-risk subgroups. Significant reduction in fracture risk after 1 yr is an important benefit in patients at high risk for fracture because, without treatment, these patients are likely to sustain new fractures in the near term.