Plenty of pills: polypharmacy prevails in patients of a Danish anticoagulant clinic.

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.