Safety and effectiveness of once-yearly zoledronic acid in Japanese osteoporosis patients: three-year post-marketing surveillance

INTRODUCTION: Zoledronic acid (5 mg; ZOL), a once-yearly bisphosphonate, reduces osteoporotic fractures and increases bone mineral density (BMD). This 3-year post-marketing surveillance examined its real-world safety and effectiveness. MATERIALS AND METHODS: This prospective, observational study included patients who started ZOL for osteoporosis. Data were assessed at baseline, 12, 24, and 36 months for safety and effectiveness. Treatment persistence, potentially related factors, and persistence before and after the COVID-19 pandemic started were also investigated. RESULTS: The safety analysis and effectiveness analysis sets included 1406 and 1387 patients, respectively, with mean age of 76.5 years. Adverse reactions (ARs) occurred in 19.35% of patients, with an acute-phase reaction in 10.31, 1.01, and 0.55% after the first, second, and third ZOL infusions. Renal function-related ARs, hypocalcaemia, jaw osteonecrosis, and atypical femoral fracture occurred in 1.71, 0.43, 0.43, and 0.07% of patients, respectively. Three-year cumulative fracture incidences were 4.44% for vertebral, 5.64% for non-vertebral, and 9.56% for clinical fractures. BMD increased by 6.79, 3.14, and 1.78% at the lumbar spine, femoral neck, and total hip, respectively, after 3-year treatment. Bone turnover markers remained within reference ranges. Treatment persistence was 70.34% over 2 years and 51.71% over 3 years. Male, age ≥ 75 years, no previous medicines for osteoporosis, no concomitant medicines for osteoporosis, and inpatient at the first infusion were related to discontinuation. There was no significant difference in the persistence rate between before and after the COVID-19 pandemic (74.7% vs. 69.9%; p = 0.141). CONCLUSION: This 3-year post-marketing surveillance confirmed the real-world safety and effectiveness of ZOL. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00774-023-01410-5.