Relationship between bone mineral density changes and fracture risk reduction in patients treated with strontium ranelate

Objective: Our objective was to analyze the relationship between bone mineral density (BMD) changes and fracture incidence during 3-yr treatment with strontium ranelate. Patients: Women from the strontium ranelate arm of the Spinal Osteoporosis Therapeutic Intervention study and the TReatment Of Peripheral OSteoporosis study were evaluated. Outcome Measures: The outcome measures included BMD at the lumbar spine, femoral neck, and total proximal femur assessed at baseline and after a follow-up of 1 and 3 yr; semiquantitative visual assessment of vertebral fractures; and nonvertebral fractures based on written documentation. Results: After 3 yr of strontium ranelate treatment, each percentage point increase in femoral neck and total proximal femur BMD was associated with a 3%(95% adjusted confidence interval, 1-5%) and2% (1-4%) reduction in risk of a new vertebral fracture, respectively. The 3- yr changes in femoral neck and total proximal femur BMD explained 76% and 74%, respectively, of the reduction in vertebral fractures observed during the treatment. Three-year changes in spine BMD were not statistically associated with the incidence of new vertebral fracture (P = 0.10). No significant associations were found between 3- yr changes in BMD and incidence of new nonvertebral fractures, but a trend was found for femoral neck BMD (P = 0.09) and for total proximal femur BMD (P = 0.07). An increase in femoral neck BMD after 1 yr was significantly associated with the reduction in incidence of new vertebral fractures observed after 3 yr (P = 0.04). Conclusion: During 3-yr strontium ranelate treatment, an increase in femoral neck BMD was associated with a proportional reduction in vertebral fracture incidence.