A COMPARATIVE-STUDY ON THE QUALITY OF ORAL ANTICOAGULANT-THERAPY (WARFARIN VERSUS ACENOCOUMAROL)

In our Center for the Surveillance of Anticoagulant Treatment, most of the 1700 patients followed-up are traditionally treated with acenocou marol, while warfarin is administered nowadays to an increasing propor tion of patients. To assess if the difference in the pharmacokinetics of these two drugs may determine a different laboratory quality of tre atment, a retrospective study was performed on the computerized files of all 142 patients on treatment with warfarin for more than 100 days and on a control group of 142 patients treated with acenocoumarol, mat ched for age, sex, disease state and duration of oral anticoagulant th erapy (OAT). The study considered 7071 assays for a total of 432 patie nt years of treatment. The overall quality of treatment was significan tly better in patients treated with warfarin (72% of controls within t he therapeutic range versus 67% on acenocoumarol, p < 0.001). Also the individual quality of therapy, which was assessed as the percentage o f patients with 75% or more assays in range, was in favour of warfarin (50.7% vs 34.5%, p < 0.05). Warfarin therapy was more stable and fewe r assays were required for treatment monitoring. Confounding factors p ossibly influencing the treatment stability, such as interfering drugs , diagnostic or therapeutical procedures requiring withdrawal of antic oagulation, were evaluated and no significant difference between the t wo groups was found. The difference in the laboratory quality of OAT w as marked in patients treated for prevention of arterial thromboemboli sm, while it was negligible in patients with venous thromboembolic dis ease, whose mean duration of OAT was considerably shorter. Since there is no evidence that acenocoumarol is more efficacious or safer than w arfarin, the latter seems to be prefer able for patients who are candi date to very prolonged OAT.