Assessment of patients’ warfarin knowledge and anticoagulation control at a joint physician- and pharmacist-managed clinic in China

PURPOSE: Warfarin is a widely used anticoagulant with a narrow therapeutic index, and it requires close monitoring and adequate patient education. We aimed to assess the knowledge level regarding warfarin therapy among its users and to identify the factors that significantly influence anticoagulation control. PATIENTS AND METHODS: Patients attending the Warfarin Clinic at the Beijing Tiantan Hospital were enrolled in this study. Patients’ knowledge on warfarin was assessed using a validated Anticoagulation Knowledge Assessment (AKA) questionnaire. Patients’ responses to each question were analyzed to identify areas of improvement in current warfarin education. International normalized ratio (INR) control was defined by the time in therapeutic range (TTR) calculated using the Rosendaal method. Spearman correlation analysis was used to investigate the association between TTR and the independent variables. RESULTS: A total of 65 patients were enrolled in this study. Eleven questions were answered correctly by <50% of the patients. A total of 858 INR results were recorded; 432 INR values (50.3%) reached the predefined goals, and the mean TTR was 49.8%±24.8%. There were significant associations between TTR and patients’ AKA scores (R=0.356, P=0.004) and between TTR and patients’ educational levels (R=0.339, P=0.006). No significant association was observed between other factors (age and duration of anticoagulation) and TTR. The INR outcome measure was positively associated with patients’ knowledge on warfarin and their educational levels. CONCLUSION: Areas for improvement in patient education have been identified, and processes for educational modification are currently in development.