What are the barriers to warfarin use in atrial fibrillation?:: Development of a questionnaire

Background: Despite evidence of their benefit and efforts to increase usage, anticoagulation for stroke prophylaxis in atrial fibrillation (AF) patients remains underutilized. Previous surveys have assessed reasons for underuse of anticoagulation but have limitations including non-structured approach for eliciting barriers and use of clinical vignettes and not patient-level data. The objectives of this study were to develop a questionnaire to assess barriers to anticoagulation use for stroke prophylaxis in AF patients at a patient- and physician-level and to conduct a preliminary field-test of the instrument. Methods: Barriers to warfarin use were identified from a literature review, input from clinical experts, and a physician focus group. A sample of US physicians who treat AF patients completed the questionnaire. Physicians ranked their reluctance on a 1-10 scale (10 = very reluctant) in general to prescribe warfarin if a specific barrier was present in a patient and then indicated critical barriers to prescribing warfarin in a sample of their own AF patients not receiving warfarin. Results: Forty-one barriers to warfarin use were identified and classified into 4 groups: patient medical characteristics (n = 17), health care system factors (n = 7), patient capability (n = 12), and patient preferenc (n = 5). Several new items were developed (e.g., difficulty in obtaining venous access), existing items were revised (e.g., timeframe for bleeding episodes subdivided into > or <= 3 months), and multi-factorial barriers (e.g., dementia, epilepsy) were explored. The factor that most strongly influenced physicians' (n = 30) decisions not to prescribe warfarin was severe bleeding < 3 months ago (mean +/- SD: 9.2 +/- 1.3) while the most prevalent critical barriers to prescribing warfarin in specific AF patients (n = 24) was patient unwilling to undergo repeat testing (29%). Conclusion: This questionnaire has the potential to assist in better understanding barriers to warfarin use with a view to addressing and then overcoming warfarin underutilization. Preliminary data suggest patient preference and capabilities are at least as important as medical characteristics as barriers to prescribing warfarin in AF patients.