Efficacy and Safety of a Once-Yearly Intravenous Zoledronic Acid 5 mg for Fracture Prevention in Elderly Postmenopausal Women with Osteoporosis Aged 75 and Older

OBJECTIVES: To determine the efficacy of once‐yearly intravenous zoledronic acid (ZOL) 5 mg in reducing risk of clinical vertebral, nonvertebral, and any clinical fractures in elderly osteoporotic postmenopausal women. DESIGN: A post hoc subgroup analysis of pooled data from the Health Outcome and Reduced Incidence with Zoledronic Acid One Yearly (HORIZON) Pivotal Fracture Trial and the HORIZON Recurrent Fracture Trial. SETTING: Multicenter, randomized, double‐blind, placebo‐controlled trials. PARTICIPANTS: Postmenopausal women (aged ≥75) with documented osteoporosis (T‐score ≤−2.5 at femoral neck or ≥1 prevalent vertebral or hip fracture) or a recent hip fracture. INTERVENTION: Patients were randomized to receive an intravenous infusion of ZOL 5 mg (n=1,961) or placebo (n=1,926) at baseline and 12 and 24 months. MEASUREMENTS: Primary endpoints were incidence of clinical vertebral and nonvertebral and any clinical fracture after treatment. RESULTS: At 3 years, incidence of any clinical, clinical vertebral, and nonvertebral fracture were significantly lower in the ZOL group than in the placebo group (10.8% vs 16.6%, 1.1% vs 3.7%, and 9.9% vs 13.7%, respectively) (hazard ratio (HR)=0.65, 95% confidence interval (CI)=0.54–0.78, P