Fracture rates in patients discontinuing alendronate treatment in real life: a population-based cohort study

• Published in: Osteoporosis international 2021-06, Vol.32 (6), p.1103-1115
• Main Authors: Sølling, A.S., Christensen, D.H., Darvalics, B., Harsløf, T., Thomsen, R.W., Langdahl, B.
• Format: Article
• Language: English
• Subjects: Alendronic acid; Bisphosphonates; Cohort analysis; Endocrinology; Fractures; Medicine; Medicine & Public Health; Original Article; Orthopedics; Osteoporosis; Population studies; Population-based studies; Rheumatology; Vertebrae
• ISSN: 0937-941X; 1433-2965
• DOI: 10.1007/s00198-020-05745-x

Summary In this nationwide register-based cohort study, we found no difference in the risk of fractures in patients discontinuing versus continuing alendronate (ALN) treatment after 5 years. Introduction Information on fracture risk in patients discontinuing ALN in a real-life setting is sparse. We aimed to examine ALN discontinuation patterns, compare fracture rates in patients discontinuing versus continuing ALN after 5 years of treatment, and define determinants of fractures in ALN discontinuers. Methods A nationwide population-based cohort study using Danish health registry data. Our source population was individuals who had redeemed ≥ 2 ALN prescriptions between January 1, 1995, and September 1, 2017. Results We found that 25% of all ALN initiators used ALN for less than 1 year and 43% continued treatment for at least 5 years. We classified n = 1865 as ALN discontinuers and n = 29,619 as ALN continuers. Using Cox proportional hazards regression analysis and an “as-treated” approach, we observed no increased risk of any fracture (incidence rate ratio (IRR) 1.06, 95% CI 0.92–1.23), vertebral fracture (IRR 0.59, 95% CI 0.33–1.05), hip fracture (IRR 1.04, 95% CI 0.75–1.45), or major osteoporotic fracture (IRR 1.05, 95% CI 0.88–1.25) in the ALN discontinuers compared to continuers during a follow-up time of 1.84 ± 1.56 years (mean ± SD) and 2.51 ± 1.60 years, respectively. ALN re-initiation was a major determinant of follow-up among the discontinuers. Old age (> 80 vs. 50–60 years, unadjusted IRR 2.92, 95% CI 1.18–7.24) was the strongest determinant for fractures following ALN discontinuation. Conclusion In a real-world setting, less than 50% continued ALN treatment for 5 years. We found no difference in the risk of fractures in patients discontinuing versus continuing ALN after 5 years.