A pilot feasibility study to assess knowledge and behaviors related to warfarin therapy

Purpose: In order to effectively design studies to improve warfarin therapy, it is important to have an understanding of patients' knowledge and behaviors related to warfarin therapy. The objective of this pilot study was to characterize the results of and feasibility of administering heath literacy, numeracy, nuisance bleeding and oral anticoagulation knowledge (OAK) questionnaires to patients who have recently started warfarin in two local anticoagulation clinics. 

Methods:   Subjects were included if they started warfarin within the previous 2 months, were >20 years of age, and had an INR goal of 2-3.  Demographic and clinical information was collected and subjects completed the following validated questionnaires: REALM-R (health literacy, max score of 8, higher score=better literacy), Subjective Numeracy Scale (mathematical competency, max score of 8, higher score=better numeracy), Modified Bleed Score (nuisance bleeding assessment, max score of 10, higher score=more nuisance bleeding), and OAK test (20 questions, max 100%, higher score=better knowledge).  Data were analyzed using descriptive statistics.

Results: Twenty subjects provided written informed consent.  Subjects were primarily Caucasian (60%), 62±18 (mean±SD) years of age and taking warfarin for atrial fibrillation or treatment of DVT or PE.  The mean±SD REALM –R score was 6.7±2.1, numeracy was 4.0±1.0, nuisance bleeding was 1.8±1.9 and OAK was 70%±10%.  The administration of the questionnaires took approximately 12 minutes per patient.  Questionnaires were reliably administered by both pharmacists and pharmacy students. 

Conclusion:   It was feasible to administer these questionnaires in an anticoagulation clinic. In addition, there was a significant amount of variability in patient responses, suggesting that some patients may require additional counseling related to behavior or knowledge.  Thus, these questionnaires can potentially be used to identify patients requiring targeted behavior or warfarin knowledge counseling.