Common Questions
What is the evidence that bisphosphonates can prevent fractures in osteopenic women without prior fracture?
There is some evidence that alendronate can reduce the risk of vertebral fractures in women with T scores of the femoral neck between -1.5 and -2.5 who have not had a previous fracture. In a subgroup analysis of the Fracture Intervention Trial, alendronate (5 mg a day that was increased to 10 mg/day after one year) decreased both clinical and radiographic vertebral fractures as compared to placebo by 54% and 36%, respectively over a 4-5 year period (1). However, it should be emphasized that the overall radiographic vertebral fracture rate was very small, 0.4%/yr in the alendronate group and 0.6%/yr in the placebo group. Thus the number of fractures prevented with alendronate would be very low and not worth the cost or potential side effects of the medication.
A recent meta-analyses of randomized controlled trials evaluating the effect of alendronate and risedronate on vertebral and nonvertebral fractures in prevention and treatment of osteoporosis have found that the number of fractures in the prevention trials was so small that the impact of bisphosphonates on fracture rates could not be reliably determined (2). It was estimated that the NNT to prevent a vertebral or nonvertebral fracture over a two-year period would be 1790 in a low risk population (0.12% risk of a vertebral fracture over 2 years as defined by BMD) with alendronate and 2315 with risedronate.
A recent study has found that treating osteopenic postmenopausal women without a history of fracture or other BMD dependent risk factor for fracture is not cost effective (3).
FDA approval of a 5 mg dose to "prevent osteoporosis" is based on studies showing increases in bone density in osteopenic women.
- Quandt SA, Thompson DE, Schneider DL, Nevitt MC, Black DM, for The Fracture Intervention Trial Research Group.. Effect of alendronate on vertebral fracture risk in women with bone mineral density T scores of -1.6 to -2.5 at the femoral neck: The Fracture Intervention Trial. Mayo Clin Proc 2005; 80: 343-349.
- Cranney A, Guyatt G, Griffith L, Wells G, Tugwell P, Rosen C, The Osteoporosis Methodology Group and the Osteoporosis Research Advisory Group. IX: Summary of meta-analyses of therapies for postmenopausal osteoporosis. Endocr Rev 2002; 23: 570-578.
- Schousboe JT, Nyman JA, Kane RL, Ensrud KE.. Cost-effectiveness of alendronate therapy for osteopenic postmenopausal women.. Ann Intern Med 2005; 142: 734-41.