ABSTRACT
BACKGROUND
Polypharmacy, defined as the concomitant use of multiple medications, is very common in the elderly and may trigger drug-drug interactions and increase the risk of falls in patients receiving vitamin K antagonists.
OBJECTIVE
To examine whether polypharmacy increases the risk of bleeding in elderly patients who receive vitamin K antagonists for acute venous thromboembolism (VTE).
DESIGN
We used a prospective cohort study.
PARTICIPANTS
In a multicenter Swiss cohort, we studied 830 patients aged ≥ 65 years with VTE.
MAIN MEASURES
We defined polypharmacy as the prescription of more than four different drugs. We assessed the association between polypharmacy and the time to a first major and clinically relevant non-major bleeding, accounting for the competing risk of death. We adjusted for known bleeding risk factors (age, gender, pulmonary embolism, active cancer, arterial hypertension, cardiac disease, cerebrovascular disease, chronic liver and renal disease, diabetes mellitus, history of major bleeding, recent surgery, anemia, thrombocytopenia) and periods of vitamin K antagonist treatment as a time-varying covariate.
KEY RESULTS
Overall, 413 (49.8 %) patients had polypharmacy. The mean follow-up duration was 17.8 months. Patients with polypharmacy had a significantly higher incidence of major (9.0 vs. 4.1 events/100 patient-years; incidence rate ratio [IRR] 2.18, 95 % confidence interval [CI] 1.32–3.68) and clinically relevant non-major bleeding (14.8 vs. 8.0 events/100 patient-years; IRR 1.85, 95 % CI 1.27–2.71) than patients without polypharmacy. After adjustment, polypharmacy was significantly associated with major (sub-hazard ratio [SHR] 1.83, 95 % CI 1.03–3.25) and clinically relevant non-major bleeding (SHR 1.60, 95 % CI 1.06–2.42).
CONCLUSIONS
Polypharmacy is associated with an increased risk of both major and clinically relevant non-major bleeding in elderly patients receiving vitamin K antagonists for VTE.
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Acknowledgements
This work was supported by a grant of the Swiss National Science Foundation (no. 33CSCO-122659/139 470). We would like to thank all collaborators of the SWITCO65+ study.
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The authors declare that they do not have a conflict of interest.
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Leiss, W., Méan, M., Limacher, A. et al. Polypharmacy is Associated with an Increased Risk of Bleeding in Elderly Patients with Venous Thromboembolism. J GEN INTERN MED 30, 17–24 (2015). https://doi.org/10.1007/s11606-014-2993-8
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DOI: https://doi.org/10.1007/s11606-014-2993-8