Prolongation of the Interval Between Monitoring of Warfarin in Stable Patients

• Status: Completed
• Trial end date: 2010-02-01
• Target enrollment: 0
• Participant gender: All

Summary

Patients with mechanical heart valve prosthesis or with irregular beat (atrial fibrillation) have a high risk of blood clot formation. Such clots can result in a stroke. The patients are treated with warfarin - a "blood thinner" - to prevent these complications. The treatment has to be monitored with a blood test called Prothrombin time (PT) every 1-4 weeks. The dose of warfarin has to be changed whenever the PT result is outside of the treatment range. If the result is too low there is an increased risk of blood clots. If, instead, the result is too high there is a risk of bleeding. One third of the patients have very stable PT results and hardly ever have to change the dose.

The investigators hypothesis is that these patients can go less often, e.g. every 12 weeks, for the blood tests.

• Phase: Phase 2
• Accepts Healthy Volunteers?: No

Details

• Lead Sponsor: Hamilton Health Sciences Corporation
• Collaborator: The Physicians' Services Incorporated Foundation
• Treatments: Warfarin

Criteria

Inclusion Criteria:

• Patients on long-term warfarin (for prophylaxis of arterial embolism in patients with atrial fibrillation or mechanical heart valve replacement, or secondary prophylaxis after VTE) with a target INR of 2.0-3.0 or 2.5-3.5,

• Anticoagulant therapy managed by the clinic (HHS - General Hospital) for at least 6 months prior to enrolment, and

• Maintenance dose of warfarin unchanged for the previous 6 months or longer.

Exclusion Criteria:

• Age <18 years,

• Life expectancy of less than 1 year,

• Attending physician believes the patient is not suitable for the study (e.g. psychiatric disorder, history of non-compliance),

• Geographic inaccessibility or

• Failure to obtain written consent.