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Purpose: This study evaluated the benefits of and possible contraindications to warfarin treatment in patients with atrial fibrillation (AF) prior to the introduction of new oral anticoagulants using health registry data from inpatient care, specialist ambulatory care, and primary care. Methods: This is a cohort study including all patients in the region of Stockholm, Sweden (2.1 million inhabitants) with a diagnosis of non-valvular AF ( n = 41 810) recorded during 2005-2009. The risks of suffering ischemic stroke, bleeding, or death with warfarin, aspirin, or no antithrombotic treatment during 2010 were related to CHADSVASc scores, age, and complicating co-morbidities. Results: One-year risks for ischemic stroke were 1.0-1.2 % with aspirin, 0-0.3 % with warfarin, and 0.1-0.2 % without treatment at CHADSVASc scores 0-1. Among the aspirin-treated patients with CHADSVASc scores ≥2, half had possible contraindications and high risks for ischemic stroke (5.2 %), bleeding (5.0 %), and death (19.3 %). The other half of the patients with no identified contraindications had a high risk for ischemic stroke (4.0 %) but a low bleeding risk (1.8 %) and a moderate mortality rate (8.4 %). Conclusions: The present observations confirm earlier findings of undertreatment with warfarin and half of the high-risk patients treated with aspirin were obvious candidates for anticoagulant treatment. However, the other half of the patients had complicating co-morbidities, high bleeding risk, and poor prognosis. This and possible overtreatment of low-risk patients should be taken into account when considering more aggressive use of anticoagulant treatment. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]