Abstract
Purpose
Vitamin K antagonist (VKA) treatment can successfully prevent thromboembolic complications, but the modality has a narrow therapeutic window and numerous interactions with other pharmaceuticals. The aim of the study reported here was to describe the use of co-medications and the prevalence of polypharmacy among patients treated with VKA.
Methods
In a cross-sectional study, 250 consecutive patients (65% male, median age 68 years, most common indication for VKA treatment: atrial fibrillation) in the maintenance phase of VKA treatment were interviewed about their use of prescription medications, over-the-counter drugs and alternative medicines during the last 7 days.
Results
The interviewed patients used a median of five medications (range 1–13), including VKA. Approximately 50% of the patients also took alternative medicines. A wide range of conventional and alternative medicines were used, several of which harbour possible interactions with VKA. Polypharmacy was defined as the use of five or more medications, excluding alternative medicines. The group of polypharmacy patients included 53% of the study population. The use of amiodarone, age >50 years, the indication for VKA treatment being atrial fibrillation or mechanical heart valves and diabetes were independent predictors of polypharmacy.
Conclusions
The results of this study highlight that polypharmacy is a common phenomenon among patients on anticoagulant medication, particularly among elderly patients or those suffering from cardiovascular disease or diabetes.
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Acknowledgements
The authors would like to thank Gunhild Andreasen, Anders Vestergaard Fournaise, Tanja Graff, Anette Larsen, Bodil Leed, Pernille Tandrup Nielsen, Asta Nørregård and Kathrine Overgaard for technical assistance and Jørgen Gram for helpful comments on an early draft of the manuscript.
Financial support
This project was supported by Grant number 09–063088 from The Danish Council for Strategic Research.
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The authors have no conflicts of interest.
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Skov, J., Bladbjerg, EM., Sidelmann, J. et al. Plenty of pills: polypharmacy prevails in patients of a Danish anticoagulant clinic. Eur J Clin Pharmacol 67, 1169–1174 (2011). https://doi.org/10.1007/s00228-011-1045-0
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DOI: https://doi.org/10.1007/s00228-011-1045-0