Jason Andrade
Atrial fibrillation, the most common type of abnormal heart rhythm, affects 5 per cent of Canadians over 65. For decades, warfarin has been the drug of choice to prevent strokes related to this condition.
In the past five years, a new class of drugs has emerged for atrial fibrillation: “non-vitamin K oral anticoagulants.” These NOACs are as effective, or more effective, than warfarin in stopping the formation of blood clots, while avoiding some of warfarin’s drawbacks, including being rendered less effective by consuming foods rich in vitamin K.
Although medical guidelines now favour these newer NOACs, Jason Andrade, an assistant professor in the UBC Division of Cardiology and a cardiologist at Vancouver General Hospital, has found that physicians still reach primarily for warfarin. And, as he reported in an article in the Canadian Journal of Cardiology, he has detected a disturbing disconnect between doctors and patients in choosing the best medication for the patient.
How did you come up with these findings?
With funding from a drug company that makes one of the NOACs, we conducted a survey of 178 physicians and 266 patients throughout Canada. We asked them what traits they value in these anticoagulant drugs, and what drugs they actually prescribed or were using. We found that warfarin was still the most widely prescribed oral anticoagulant, even though it doesn’t have the attributes that patients and physicians said they most value. There was a difference between the preferred attributes, and the medication that was ultimately prescribed.
Why do physicians still gravitate to warfarin?
In a small number of cases, such as those which involve valvular atrial fibrillation, warfarin is still the more appropriate treatment. Also, its effects can be more easily reversed, if needed, than the NOACs. But there are also some non-medical factors at play. Some provinces in Canada, including British Columbia, as well as private insurers, will not cover the more expensive NOACs unless warfarin has been tried first. Also, physicians might not be as familiar with NOACs, some of which have only been available for a couple of years, and none of which were even in use 10 years ago.
So should more doctors be prescribing NOACs?
Patients and physicians should be made aware that some of these newer drugs may have the attributes that they most value, according to our survey. However, our survey also highlighted that the increased frequency of dosing for two of the NOACs may be a potential problem. Specifically, in our survey nearly one-third of patients taking drugs that required two daily doses were taking them only once a day. That was a disturbing finding – you have to take the medication as indicated to get the benefit.
As a result, given the breadth of options available, doctors need to have more detailed conversations with their patients – not only when prescribing the treatment but also during follow-up visits. When deciding to use one drug over another, they should consider the patient’s capacity to take multiple daily doses. Likewise, during follow-up visits, physicians should ask whether patients are following the recommended dosage, and if not, why not. If it appears that the patient is likely to continue to miss doses, the physician should prescribe another medication.