Background: In clinical practice, warfarin is underused for the prevention of stroke in individuals with atrial fibrillation despite unequivocal evidence of benefit and acceptable safety.
Objective: To ascertain, from primary care physicians, their beliefs and preferences regarding the use of warfarin in patients with atrial fibrillation.
Materials and methods: A questionnaire was mailed to a random sample of 1000 primary care physicians in Ontario. Physician prescribing preferences from among treatment options available (warfarin, acetylsalicylic acid, ticlopidine, no therapy and other) were recorded for four separate scenarios of atrial fibrillation with varying degrees of risk for stroke. Physician perception of the risks associated with warfarin use and their awareness of the evidence of benefit were assessed.
Results: Three hundred twenty-four physicians returned completed questionnaires. Among the four scenarios, physicians choosing not to use warfarin were three to six times more likely than physicians choosing to use warfarin to believe that there was inadequate evidence of benefit of warfarin for stroke prophylaxis, and they were four to six times more likely to be concerned about the risks of hemorrhage. These beliefs did not change significantly with scenarios describing patients with a high risk of stroke.
Conclusions: Physician reluctance to use warfarin is associated with a false understanding of the benefit to risk ratio, which arises from a low appreciation of therapeutic benefits and a high concern regarding hemorrhage.