Warfarin Therapy and Risk of Hip Fracture Among Elderly Patients

Authors

  • Muhammad Mamdani Pharm.D., M.A., M.P.H.,

    Corresponding author
    1. Institute for Clinical Evaluative Sciences, University of Toronto
    2. Faculty of Pharmacy, University of Toronto
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  • Ross E. G. Upshur M.D., M.Sc., M.A.,

    1. Department of Family and Community Medicine, University of Toronto
    2. Department of Public Health Sciences, University of Toronto
    3. Department of Family and Community Medicine, Sunnybrook and Women's College Health Sciences Centre, Toronto, Ontario, Canada
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  • Geoff Anderson M.D., Ph.D.,

    1. Institute for Clinical Evaluative Sciences, University of Toronto
    2. Department of Public Health Sciences, University of Toronto
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  • Bill R. Bartle Pharm.D.,

    1. Faculty of Pharmacy, University of Toronto
    2. Department of Pharmacy, Sunnybrook and Women's College Health Sciences Centre, Toronto, Ontario, Canada
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  • Andreas Laupacis M.D., M.Sc.

    1. Institute for Clinical Evaluative Sciences, University of Toronto
    2. Department of Health Administration of the Faculty of Medicine, University of Toronto
    3. Department of General Internal Medicine, Sunnybrook and Women's College Health Sciences Centre, Toronto, Ontario, Canada
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Institute for Clinical Evaluative Sciences, 2075 Bayview Avenue—G215, Toronto, ON, Canada M4N 3M5; e-mail: muhammad.mamdani@ices.on.ca.

Abstract

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% CI 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.

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