Evaluation of patients' knowledge on warfarin in outpatient pharmacy of a tertiary care cardiac center.

BACKGROUND: Warfarin is widely used for the prevention and treatment of cardiac, thromboembolic and hypercoagulable diseases. Since warfarin is a narrow therapeutic index medicine, it requires close monitoring when used in the outpatient setting and on long term basis. Warfarin has been found to be associated with a number of complications especially bleeding. Patients' knowledge on warfarin can improve anticoagulation control with decrease in adverse drug reaction and other associated complications. The objective was to assess knowledge level of warfarin therapy among its users and to provide adequate education and counseling to the patients.

METHODS: In the present cross sectional study, 34 patients on warfarin were interviewed. Patients' knowledge on warfarin was assessed using a validated Anticoagulation Knowledge Assessment (AKA) questionnaire comprising 29 questions. Each correct answer scored 3.45 points whereas an incorrect answer scored zero point. Patient who answered at least 21 questions correctly or scored (21 × 3.45 = 72.4%) was considered to have adequate level of knowledge or have obtained a passing score. Association between independent variables and AKA score was assessed using Pearson Chi square test or Fisher's exact test for categorical variables. Patients were counseled regarding proper warfarin use by the researcher pharmacists at the end of each data collection schedule.

RESULTS: Of the 34 patients, only 5.8% (n = 2) achieved a passing score whereas 94.1% (n = 32) failed to achieve the passing score. 67.6% of the patients (n = 23) achieved a score below 50%. More than 50% of the patients incorrectly answered 15 questions in the questionnaire. None of the patients scored 100%. No significant association was found between age, gender of patients and total warfarin score. A significant association (p < 0.05) was found between duration of warfarin therapy and total warfarin score.

CONCLUSIONS: Warfarin knowledge was poor among the patients. Hence, regular counseling with timely assessment of their understanding was felt necessary.