Comparitive study of the stability of oral anticoagulant therapy using phenprocoumon or warfarin.

Introduction:

Worldwide there are different coumarins available for oral anticoagulant treatment.

Warfarin, acenocoumarol and phenprocoumon are the coumarins most used and they differ mainly in their halflife.

A comparison between acenocoumarol and warfarin showed that warfarin was superior to the shortacting acenocoumarol. Another comparison between acenocoumarol and the long-acting phenprocoumon concluded that phenprocoumon should be prefered over acenocoumarol.



Methods:

We set up a randomised controlled trial in which an oral anticoagulant treatment with warfarin is compared to a treatment with phenprocoumon.

Patients are recruted at three different hospitals in the Netherlands at the departments of Cardiology, Internal Medicin or Orthopaedics.

Patients between 18 and 85 years with an indication for the use of oral anticoagulants for at least 3 months are invited to participate.

Inclusion started in March 2004 and is ongoing. Treatment is coordinated at the Leiden Anticoagulation Clinic. Patients are followed untill end of treatment or, for patients with an indication for prolonged treatment, during their first six months.



Endpoints:

Primary endpoints are the time spent in therapeutic range calculated according to the method of Rosendaal, the time untill an INR in the therapeutic range is reached after starting the treatment and the reaction of the INR to interruption of coumarin or vitamin K administration.

Longacting coumarin derivatives can reach a more stable anticoagulant effect. Shortacting coumarins are more easy to adjust. The halflife of warfarin lies between the halflife of acenocoumarol and phenprocoumon and can thereby possibly have the advantage of longacting coumarins as well as the advantage of shortacting coumarins.

N/A

Treatment group: oral anticoagulant treatment with warfarin.

Control group: oral anticoagulant treatment with phenprocoumon.