Primary Care Research

Clinicians may need to balance recommendations with patient preferences for anticoagulant medication to treat atrial fibrillation

Atrial fibrillation (AF) is the most common type of cardiac arrhythmia. People with AF have a risk of stroke that ranges from less than 1 percent to over 15 percent per year depending on their age and clinical factors. The drug warfarin is more effective in preventing stroke in AF patients than aspirin, but it is more costly, inconvenient (patients need regular blood monitoring), and dangerous (with 1 to 3 percent per year risk of major bleeding). Given the advantages and disadvantages of these therapies, personal preferences may play an important role in determining the optimal antithrombotic therapy for individuals with AF, suggest researchers who performed a systematic review of studies on the topic.

The researchers, supported in part by the Agency for Healthcare Research and Quality (HS10133), found that patients with AF were less inclined to go on warfarin therapy than treatment recommendations suggest. They compared the thresholds for antithrombotic treatment of 890 patients from 8 studies that determined or modeled the treatment preferences of patients with AF. All eight studies found highly variable individual thresholds above which warfarin was preferred over aspirin.

In five of eight studies, patient preferences indicated that fewer patients would prefer warfarin compared with the recommendations of the guidelines. In general, at a stroke rate of 1 percent with aspirin, half of the participants would prefer warfarin, and at a stroke rate of 2 percent with aspirin, two-thirds would prefer warfarin. In three studies, warfarin had to provide at least a 0.9 to 3 percent per year absolute reduction in stroke risk for patients to be willing to take it, corresponding to a stroke rate of 2 to 6 percent on aspirin. The researchers conclude that practicing physicians may need to balance patient preferences with treatment recommendations from clinical practice guidelines.

See "Preference-based antithrombotic therapy in atrial fibrillation: Implications for clinical decision making," by Malcolm Man-Son-Hing, M.D., Brian F. Gage, M.D., Alan A. Montgomery, Ph.D., and others, in the September 2005 Medical Decision Making 25, pp. 548-559.

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