The Danish Warfarin-Dialysis Study - Safety and Efficacy of Warfarin in Patients With Atrial Fibrillation on Dialysis

Inclusion Criteria: * Patients ≥18 years on chronic dialysis due to end-stage renal disease * Non-valvular paroxysmal, persistent, or permanent atrial fibrillation OR non-treated (for \>2 months) prevalent paroxysmal, persistent or permanent atrial fibrillation as documented by an electrocardiogram or an episode of ≥30 seconds on Holter monitor, or episodes ≥ 6 minutes on event recorders or any other recording device. * Competence to understand the study rationale, including potential risks and benefits associated with treatment, necessary for written informed consent. Exclusion Criteria: * CHA2DS2-VASc Score ≤1 * Other indications for oral anticoagulation treatment (pulmonary embolism \< 6 months, deep vein thrombosis \<3 months, mechanical heart valve prosthesis) irrespective of whether treatment is implemented * Ongoing dual antiplatelet treatment * Malignancy (with exception of non-melanoma skin cancer) with recent \< 1 year, ongoing, or planned curative, or palliative chemo- , radiation-, and/or scheduled surgical therapy * Endoscopy with gastrointestinal ulcer \<1 month * Esophageal varices * Autoimmune og genetic coagulation disorders * Congenital alactasia, Lapp Lactase deficiency or glucose-galactose malabsorption * Pending spinal tap * Cerebrovascular malformations * Arterial aneurysms * Ulcers or wounds (Wagner grad \>1) * Bacterial endocarditis \< 3 months * Active bleeding contraindicating anticoagulation * Any non-elective and/or non-ambulant surgery \<7 days * Cerebral hemorrhage \<4 weeks * Thrombocytopenia (platelet count \<100 × 109/L) \<30 days. * Severe liver insufficiency (spontaneous international normalized ratio \>1.5) \<30 days. * Known intolerance to warfarin * Use of hypericum perforatum / St. John's Wort * Uncontrolled hypertension (repeat blood pressure \>180/110 mmhg) \< 30 days * Uncontrolled hyperthyroidism (thyroid-stimulating hormone \<0.1μIU/mL) \<30 days * Pregnancy or lactation * Participation in other ongoing intervention trials adjudged to influence study outcomes