Association of Plasma Warfarin level with Monitoring Parameters Among Patients Treated at Hematology Referral Clinic, Tikur Anbessa Specialized Hospital
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Date
2015-06
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Addis Ababa University
Abstract
Warfarin monitoring poses challenge to the treatment of thromboembolic disorders
because out-of-range INRs which is encountered as a result of changes in numerous
factors. The fluctuation of INR in some patients might be dangerous because of the
narrow therapeutic index of warfarin. The objective of this study is to evaluate the
association of plasma warfarin level with warfarin the clinical monitoring parameter,
INR and related parameters. Institution based cross-sectional prospective study was
conducted recruiting 57 eligible patients on warfarin treatment at hematology referral
clinic of Tikur Anbessa Specialized Hospital. Clinical data was retrieved from patient
cards and plasma warfarin level were determined using High Pressure Liquid
Chromatography with Ultra Violet – Visible detector. The associations of plasma
concentration with INR and weekly dose were low (rho = 0.375 at p = 0.006 and r = 0.283
at p = 0.04) respectively. There was also statistically significant difference in the mean
plasma warfarin concentration of patients who took effect enhancing co-medication and
those who took non-effect changing co-medication (p <0.001) as well between the mean
plasma concentration of patients who took effect diminishing co-medication and those
who took non-effect changing co-medications was also statistically significant (p =
0.005). In conclusion clinical monitoring parameters of warfarin have low association
with plasma warfarin level. The low correlation indicates the importance of plasma
warfarin concentration monitoring in some situations, especially when the ideal INR is
difficult to achieve the target where by patient safety can be affected.
Key Words: Warfarin, INR, Dose, Association, co-medications
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Keywords
Warfarin; INR; Dose; Association; co-medications