Time to Onset of Efficacy in Fracture Reduction with Current Anti-osteoporosis Treatments

Early prevention of future fracture is an important goal in those at risk. A similar 3-year fracture efficacy is reported for most osteoporosis agents. Onset of fracture efficacy may be useful to help tailor treatment based on risk. We reviewed the peer-reviewed literature for onset of fracture efficacy data on the commonly prescribed osteoporosis treatments. All papers were reviewed independently by at least two reviewers for onset of efficacy for morphometric vertebral fracture (MVF), clinical vertebral fracture (CVF), nonvertebral fracture (NVF), hip fracture, and any clinical fracture (ACF). Alendronate is reported to reduce multiple CVF by 6 months; all CVF, NVF, and multiple ACF by 12 months; and all ACF and hip fracture by 18 months. Ibandronate is reported to reduce MVF by 12 months and NVF by 36 months. Raloxifene is reported to reduce CVF by 3-6 months and NVF by 36 months. Risedronate is reported to reduce CVF and NVF by 6 months, and hip fracture by 12 months. Strontium ranelate is reported to reduce MVF, CVF, NVF, and ACF by 12 months, and hip fracture by 36 months. Zoledronic acid is reported to reduce MVF, CVF, and ACF by 12 months, NVF by 24 months, and hip fracture by 36 months. Although direct comparisons are limited, based on the available literature, risedronate, followed by alendronate, have the earliest onset of benefit across the range of fracture types. Onset of efficacy may be an important consideration in the selection of treatment for some patients.