Effects of long-term strontium ranelate treatment on the risk of nonvertebral and vertebral fractures in postmenopausal osteoporosis - Results of a five-year, randomized, placebo-controlled trial

Objective. This study was undertaken to assess the effect of strontium ranelate on nonvertebral and vertebral fractures in postmenopausal women with osteoporosis in a 5-year, double-blind, placebo-controlled trial. Methods. A total of 5,091 postmenopausal women with osteoporosis were randomized to receive either strontium ranelate at 2 gm/day or placebo for 5 years. The main efficacy criterion was the incidence of nonvertebral fractures. In addition, incidence of hip fractures was assessed, by post hoc analysis, in the subset of 1,128 patients who were at high risk of fractures (age 74 years or older with lumbar spine and femoral neck bone mineral density T scores -2.4 or less). The incidence of new vertebral fractures was assessed, using the semi-quantitative method described by Genant, in the 3,646 patients in whom spinal radiography (a nonmandatory procedure) was performed during the course of the study. Fracture data were analyzed using the Kaplan-Meier survival method. Results. Of the 5,091 patients, 2,714 (53%) completed the study up to 5 years. The risk of nonvertebral fracture was reduced by 15% in the strontium ranelate group compared with the placebo group (relative risk 0.85 [95% confidence interval 0.73-0.99]). The risk of hip fracture was decreased by 43% (relative risk 0.57 [95% confidence interval 0.33-0.97]), and the risk of vertebral fracture was decreased by 24% (relative risk 0.76 [95% CI 0.65-0.88]) in the strontium ranelate group. After 5 years, the safety profile of strontium ranelate remained unchanged compared with the 3-year findings. Conclusion. Our findings indicate that treatment of postmenopausal osteoporosis with strontium ranelate results in a sustained reduction in the incidence of osteoporotic nonvertebral fractures, including hip fractures, and vertebral fractures over 5 years.