Risedronate associated with slightly higher risk of hip fracture during drug holiday compared with alendronate

Risedronate and alendronate are common oral bisphosphonates prescribed to patients with osteoporosis. These bisphosphonates bind to bone and continue to affect bone turnover for extended periods, even after therapy discontinuation. Current guidelines recommend stopping these medications after 3 to 5 years due to both the strength of these bisphosphonate bonds and possible adverse events.

Researchers from Brown University School of Public Health and the University of Toronto studied administrative health record data from patients in Ontario, Canada who had taken alendronate or risedronate for at least 3 years and then had a drug holiday to examine the comparative risk of hip fracture during drug holidays. Researchers excluded people who had a fracture or entered a nursing home very shortly after treatment was stopped (within 120 days) to avoid including people who were stopping therapy due to declining health rather than a drug holiday. After conducting a propensity score–matched cohort analysis, the authors found that the risk for hip fracture was very low overall but slightly higher among risedronate users than alendronate users during the drug holiday (12.4 fractures per 1,000 patient-years for risedronate vs. 10.6 per 1,000 patient-years for alendronate). The difference in hip fracture also did not appear until 2 years after the drug holiday period started. The authors say that further research should examine when to start or restart therapy based on length and type of treatment, patient characteristics, and relative risk of hip fracture.