[Thrice-weekly warfarin administration: results in 12 hemodialysis patients]

Abstract

We report our experience of thrice-weekly warfarin administration, at the end of the dialysis session, in 12 patients (average age: 79 ± 5 years). In 10 cases, indication for anticoagulation therapy was atrial fibrillation, in one case a mechanical heart valve, in another case axillo femoral bypass. The International Normalized Ratio (INR) therapeutic goal was between 2 and 3, except for the patient with a mechanical aortic heart valve, whose goal was between 2.5 and 3.5. The INR was determined during the first dialysis session of the week. The thrice-weekly warfarin dose was based on this result. INR stability was assessed for each patient over an uninterrupted period of treatment of at least 6 months. The average duration of warfarin treatment was 20 ± 5 months. One in two patients had hypertensive nephropathy. The average Charlson co-morbidity score was 9 ± 1. Four patients were also taking aspirin or clopidogrel. The 10 patients with atrial fibrillation had an average CHA(2)DS(2)-VASc score of 4.4 ± 0.8. The average haemorrage risk HAS-BLED score was 3.3 ± 0.6. The average weekly warfarin dose was 23 ± 5 mg. No thrombotic events were observed. The side effects of warfarin were minor in most cases: (1) INR more than 6 in two cases without associated bleeding; (2) minor bleeding (nose, bladder) in three cases. One case of skin necrosis was observed. No cases of major bleeding (requiring blood transfusion) were observed. Only one patient was admitted into hospital as a result of warfarin treatment (the case of skin necrosis). Five hundred and forty-seven INR results were analyzed: 65% of these results were within the therapeutic goal, only 3% were either beneath 1.5 or over 4. To conclude, warfarin administration at the end of the dialysis session is efficient and associated with remarkable INR stability in the goal. It enables precise dose adaptation and optimum therapeutic observance, which in turn reduces the risk of bleeding.

Keywords: Atrial fibrillation; Chronic haemodialysis; Fibrillation auriculaire; Hémodialyse chronique; Warfarin; Warfarine.