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Investigating patients' knowledge and use of the patient information leaflet regarding their warfarin therapy.

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Background: Warfarin is the gold standard drug of choice to manage thrombotic disorders, but may interact with certain foods and drugs, resulting in unwanted adverse effects. The use of patient information leaflet (PIL) as a standardized educational material is essential to ensuring optimal therapy. The aim of the study was to determine patient’s knowledge and use of PIL regarding their Warfarin therapy. Methods: A descriptive cross-sectional survey design required respondents to complete an anonymous questionnaire survey over 18 weeks. Responses were captured and analyzed using STATA version 13. Results: 34 patients responded in this study, of whom 56% (n=19) were males and 73.5% (n=25) had been on Warfarin treatment for less than 10 years. Only 50% (n=17/34) had knowledge of the PIL, 91% (n=31) knew about the International Normalized Ratio (INR) and 97% (n=33) understood its importance. While 76.5% (n=26) had knowledge of other drugs and foods that interact with Warfarin, and 70.5% (n=24) knew that consuming leafy green vegetables could reduce its effectiveness, only 58.8 % (n=20) understood the effect of alcohol on Warfarin. 91% (n=31) scored above 50% on the Oral Anticoagulant Knowledge (OAK) Test, with a moderate negative correlation between this and the respondent’s age (Spearman correlation = -0.27). Conclusion: INR testing and its importance in Warfarin therapy appeared to be known by most respondents, their lack of knowledge about PIL, as well as drug, alcohol and food interactions with Warfarin highlights the need for education and counseling to reinforce their knowledge and use of PIL.


Masters Degree. University of KwaZulu-Natal, Durban.