The association between long-term bisphosphonate use and the risk of fracture among women aged 50 or older with osteoporosis

Background: Osteoporosis is a prevalent disease, and bisphosphonates can effectively reduce the risk of osteoporotic fractures. However, the association between the length of the medication treatment and the risk of fractures remains unclear. The purpose of this study was to evaluate the association between long-term bisphosphonate use (treatment duration ≥5 years) and the risk of fractures among women with osteoporosis aged 50 or older. Materials and Methods: We conducted a retrospective cohort study by using the 2001-2011 National Health Insurance Research Database in Taiwan. We included women who were 50 years or older, who had a diagnosis of osteoporosis, and who were newly initiating oral bisphosphonates between January 1, 2002 and December 31, 2003. The index date was the date of the first dispensing of oral bisphosphonate during the enrollment period. Women were considered to be using bisphosphonates until they had a gap in supply of more than 3 months. We classified bisphosphonate use as long term (≥5 years) and regular (<5 years) based on its length of use. The dependent variable was the time to the first observed clinical fracture. Cox-proportional hazard regression models were used to evaluate the association between long-term bisphosphonate use and the risk of fractures. Results: The study included 1342 women with a mean age of 71 years. Of them, 83 (6.2%) were long-term bisphosphonate users. A total of 185 (13.8%) had a fracture. After adjustments, long-term bisphosphonate use was not associated with a lower risk of fractures than was regular bisphosphonate use (adjusted hazard ratio: 1.49, 95% CI: 0.91-2.45). Conclusion: This study found no evidence of a lower risk of fractures to be associated with long-term bisphosphonate use among women aged 50 or older with osteoporosis in Taiwan. Orthopedists as well as other healthcare providers should be aware of the limited benefits of long-term bisphosphonate use.