Chinese patients on warfarin therapy : their knowledge and learning experience

Abstract

Background: Warfarin is a vitamin K antagonist that is the most commonly prescribed anticoagulant, and its continued use is anticipated even with the new anticoagulants. It is well known that warfarin therapy is challenging to manage given its narrow therapeutic range and potential life-threatening side effects, and is well known to have multiple drug-drug, drug-disease and drug-food interactions. The challenge is even greater in a Chinese community as many warfarin-diet interactions are unknown in the case of Chinese dietary items and herbs. Patients’ knowledge of anticoagulation may have an impact on its control. A better understanding of patient knowledge and learning experience of warfarin therapy may help to develop targeted patient education.

Objective: This study aims to assess patients’ knowledge of warfarin therapy and the association between patients’ knowledge and anticoagulation control, and their experience of learning about warfarin therapy.

Method: A mixed method research design with both quantitative and qualitative sections was employed. The quantitative study included two parts: (1) a cross-sectional survey using a validated tool to assess anticoagulation knowledge (the OAK test) and a warfarin-diet interaction dietary item list, and (2) a chart review of the INR result of each participant for the past year to compute the result of time in therapeutic range (TTR) reflecting the quality of anticoagulation control. The qualitative section was carried out by means of semi-structured in-depth interviews.

Results: Among the 292 Chinese adult participants, the knowledge level (OAK test) was generally not good with the mean score on the test only 59.55. Only 56 (19.18%) participants attained the pass mark of _75% in the OAK test. Gender, age, education, and concerns regarding warfarin therapy were found to be significantly associated with the knowledge-of-warfarin score. Patients’ warfarin-diet interaction knowledge was also evaluated; the food score correlated significantly with the OAK score. Chinese patients also faced the challenge of not having adequate information about interactions between warfarin and some Chinese food items. Also, the mean score of participants’ TTR was found to be 57.14%. However, it was found that there was no significant relationship between warfarin knowledge and anticoagulation control. The most significant factor affecting good anticoagulation control was the duration of warfarin use. Patients new to warfarin were most in need of help. The qualitative section helped to gain insight into this finding. From the qualitative findings, two themes were derived: (1) the learning of warfarin therapy is a process, which patients need to undergo to explore how their bodies would react to warfarin therapy, and how they need to adjust their lifestyle and dietary habits, and (2) a journey of coming to terms with warfarin therapy, how they have developed their sense of living with the therapy and established their own personal system to cope with it. This is crucial to achieving good anticoagulation control.

Conclusion: Patients’ knowledge of warfarin therapy generally was not well advanced; however, knowledge seems to be not the only important factor in good anticoagulation control. Patients’ experience provided an insight - that learning about warfarin is a process, in which they develop their own sense and system to live with the drug and the way of life it imposes. Healthcare providers might try to adopt a more patient-centered approach in formulating education strategies to meet patient needs better.