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Prevalence of Nutritional and Herbal Medicine use and its Impact on Warfarin Dose and Response in a Tertiary Referral Hospital in Kenya

Author: Nyamu D. G , Guantai N.A. , Osanjo G.O. , Aklilu E. , Tele A.K.
Is Part Of: Pharmaceutical Journal of Kenya, Volume 24, No. 1 (2019)
Background: Warfarin is the most extensively prescribed oral anticoagulant drug in Kenya and the rest of the world, owing to its demonstrated efficacy and affordability. Dosing and the response to warfarin are complicated by the fact that it is affected by nutrition status as well as commonly used herbal products.
Objective: To determine the prevalence of nutritional and herbal medicine use and its impact on warfarin dose and response among outpatients on anticoagulation therapy.
Study Area and Setting: Kenyatta National Hospital Anticoagulation Clinics.
Study Designs: Cross-sectional study.
Participants and Sample sizes: One hundred and eighty patients aged ≥18 years, who voluntarily signed informed consent to participate. Patients had to be on long term warfarin therapy (≥ 28 days), did not suffer from uncontrolled hypertension, peptic ulcer, and inherited coagulopathies or liver diseases. Mentally challenged patients and pregnant women were excluded.
Methods: The participants’ clinical data such as details of sociodemographic characteristics and dietary habits such as type of food consumed, frequency of consumption, herbal and nutritional supplementation were obtained through direct patient interviews. The data on clinical indication and warfarin doses were acquired from patients’ medical records. Warfarin response was determined by measurements of international normalized ratios (INRs), whose therapeutic range was set at 2-3 as recommended in the international guidelines.
Data Management: Data was analyzed using IBM Statistical Package for Social Sciences version 23. Frequencies were done to describe the prevalence of use of the nutritional and herbal substances. Student t-test and Chi-square tests were used to determine the strength of associations between warfarin maintenance doses and consumption of various foods or nutritional supplements as well as INR therapeutic levels, while setting the threshold for statistical significance at p≤0.05.
Results: Patients were generally middle aged at 43.4 (±13.2) years, and majority, 77.0 %( n=138) were females and in the 3rd to 5th decades (55.5 %) of their lives. The median duration of warfarin therapy was 753 (range 31-11433) days. The mean maintenance dose of warfarin was 6.17 ±2.75mg per day. The prevalence of use of garlic and ginger herbal medicine was 18.9% and 12.2%, respectively. Majority of patients (70 %) were consuming vegetables and fruits for 3-7 times in a week. Dietary and herbal medicine use did not significantly impact on warfarin doses and level of anticoagulation (P>0.05).
Conclusion: The prevalence of herbal medicine use among the patients on long term warfarin therapy is low. Dietary habits did not affect warfarin dose and response. Similar correlation studies with the inclusion of conventional drugs and comorbidities may improve warfarin dosing and determine anticoagulation response among patients.

Keywords: Anticoagulation, herbal medicine use, nutritional supplements, warfarin response, warfarin dose, Kenya
Publisher: The Pharmaceutical Society of Kenya
ISSN: 2411-6386