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CADTH Report / Project in Briefs [Internet]. Ottawa (ON): Canadian Agency for Drugs and Technologies in Health; 2011-.

CADTH Report / Project in Briefs [Internet].

Optimal Warfarin Management for Prevention of Thromboembolic Events in Patients with Atrial Fibrillation

Created: December 2011.

Key Messages

Warfarin has been used for more than 60 years and is safe and effective in preventing stroke and other complications in patients with atrial fibrillation — but there’s still room for improvement in how it’s managed:

  • Managing warfarin therapy should follow a structured plan, whether it is taking place in a specialized anticoagulation clinic, a family doctor’s or specialist’s office, or other care setting.
  • A structured approach to managing warfarin therapy in any care setting should:
    • ensure ongoing patient education and follow-up
    • make use of dosing tools
    • involve caregivers and other health professionals.
  • Patient self-testing and self-management of warfarin may be an option for some patients, but is not recommended for most.


Atrial fibrillation, also called A-Fib or AF, is the most common abnormal heart rhythm. It affects an estimated 350,000 Canadians. Although patients with A-Fib often have no symptoms, it can lead to serious medical complications — such as stroke or other blood clots.


Warfarin is a drug that has been used for more than 60 years to prevent strokes and other complications in patients with A-Fib. It does not treat the abnormal heart rhythm. Warfarin works by making the blood less likely to form clots.


Warfarin is effective in preventing strokes and other blood clots in patients with A-Fib. But there are some challenges with warfarin therapy. Warfarin interacts with some foods and several other drugs. Too much warfarin can put a patient at risk for bleeding. Too little warfarin can result in a stroke or other blood clot. Finding the perfect warfarin balance can be tricky, and requires different dosing strategies for different patients. Frequent blood tests to monitor warfarin therapy are required. Most patients with A-Fib taking warfarin are followed by their family doctor (usual care), but some are seen in specialized anticoagulation clinics, while others may manage their own warfarin therapy. But how is warfarin therapy best managed to get the greatest possible benefit from the drug?


An expert panel made optimal use recommendations on managing warfarin therapy, based on a systematic review of the clinical evidence and a review of the economic evidence.

An analysis of current practice helped to identify gaps in knowledge and practice and will inform knowledge mobilization activities.

Research Results

It’s unclear from the available evidence whether specialized anticoagulation clinics result in improved clinical outcomes compared with usual care. The evidence on patient self-testing and self-management was mixed, but they may lead to improvements in some patient outcomes. The costs and cost-effectiveness of these alternatives to usual care are uncertain.

For complete reports and intervention tools on this topic, please visit www.cadth.ca.

DISCLAIMER: The information in this Project in Brief is intended to help health care decision‐makers, patients, health care professionals, health systems leaders, and policy‐makers make well‐informed decisions and thereby improve the quality of health care services. The information in this Project in Brief should not be used as a substitute for the application of clinical judgment in respect of the care of a particular patient or other professional judgment in any decision‐making process nor is it intended to replace professional medical advice. While CADTH has taken care in the preparation of the Project in Brief to ensure that its contents are accurate, complete, and up‐to‐date, CADTH does not make any guarantee to that effect. CADTH is not responsible for any errors or omissions or injury, loss, or damage arising from or as a result of the use (or misuse) of any information contained in or implied by the information in this Project in Brief.

CADTH takes sole responsibility for the final form and content of this Project in Brief. The statements, conclusions, and views expressed herein do not necessarily represent the view of Health Canada or any provincial or territorial government. Production of this Project in Brief is made possible through a financial contribution from Health Canada.

Copyright © 2011- CADTH.

Except where otherwise noted, this work is distributed under the terms of a Creative Commons Attribution-NonCommercial- NoDerivatives 4.0 International licence (CC BY-NC-ND), a copy of which is available at http://creativecommons.org/licenses/by-nc-nd/4.0/

PMID: 27170983

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