Warfarin Therapy and Risk of Hip Fracture Among Elderly Patients

STUDY OBJECTIVE: To ascertain the relationship between warfarin therapy and subsequent hip fracture in a large elderly population. DESIGN: Retrospective, population-based cohort study. SETTING: Population-based health care administrative databases for Ontario, Canada. PATIENTS: Elderly patients receiving warfarin (52,701 patients), thyroid replacement therapy (40,555), an oral corticosteroid (43,915), or a proton pump inhibitor (60,383). The proton pump inhibitor group served as controls. MEASUREMENTS AND MAIN RESULTS: The association between warfarin therapy and subsequent hospitalization for hip fracture in elderly patients was examined by researching administrative data from January 1, 1994-March 31, 1999, for the elderly population of Ontario. Relative to patients receiving proton pump inhibitors, patients receiving warfarin (adjusted risk ratio [aRR] 0.94, 95% confidence interval [CI] 0.81-1.09) or thyroid replacement therapy (aRR 1.02, 95% Cl 0.89-1.18) incurred similar risks of hip fracture. As expected, patients receiving oral corticosteroids incurred an increased risk (aRR 1.44, 95% CI 1.21-1.70) relative to patients receiving proton pump inhibitors. CONCLUSION: Warfarin was not associated with increased risk of hip fracture.