Osteoporosis drug holidays tied to small rise in hip fracture risk
21 Jan 2022
Elderly patients with hip fractures better treated at smaller health facilities.The risk for hip fracture slightly increases following osteoporosis drug holidays after long-term therapy with risedronate compared with alendronate, a study has found, adding that future research must examine how best to lessen such risk.
This population-based, matched, cohort study was conducted to assess the comparative risks of drug holidays after long-term (≥3 years) risedronate versus alendronate therapy. The authors accessed province-wide healthcare administrative databases providing coverage to Ontario, Canada, residents aged ≥65 years between November 2000 and March 2020.
Older adults on long-term risedronate therapy and a drug holiday were matched 1:1 on propensity score to those who had long-term alendronate therapy and a drug holiday.
Hip fracture within 3 years after a 120-day ascertainment period was the primary outcome, while secondary ones included shorter follow-up and sex-specific estimates. The authors estimated hazard ratios (HRs) for fracture risk between groups using Cox proportional hazards models.
Overall, 25,077 propensity score-matched pairs (mean age 81 years, 81 percent women) met the eligibility criteria. Hip fractures occurred more frequently among risedronate than alendronate drug holidays (12.4 vs 10.6 events per 1,000 patient-years; HR, 1.18, 95 percent confidence interval [CI], 1.04‒1.34; 915 total hip fractures).
The association was offset by the inclusion of any fracture as the outcome (HR, 1.07, 95 percent CI, 1.00‒1.16) and by shorter drug holidays (1 year: HR, 1.03, 95 percent CI, 0.85‒1.24; 2 years: HR, 1.14, 95 percent CI, 0.96‒1.32).
This study was limited by potential unmeasured confounding due to use of healthcare administrative data only. In addition, some secondary analyses covered few events.
“An osteoporosis drug holiday is recommended for most patients after 3 to 5 years of therapy,” the authors said. “Risedronate has a shorter half-life than alendronate, and thus the residual length of fracture protection may be shorter.”