Predisposing Factors Leading to Warfarin Toxicity

Introduction: Warfarin is a commonly utilized anticoagulant in the management of thrombosis, either prevention or treatment, with bleeding problems as one of the major adverse effect because of its narrow therapeutic index. Objective: To determine the frequency of various factors leading to warfarin toxicity which was defined as patients presented with International Normalized Ratio (INR) greater than five. Setting: Department of Adult Cardiology at National Institute of Cardiovascular Diseases (NICVD), Karachi, Pakistan. Methodology: The study type is descriptive, cross sectional. All patients who fulfilled the inclusion criteria and visited Department of Adult Cardiology at NICVD, Karachi, Pakistan were included. After ethical approval and informed and written consent. The collected data was entered using IBM SPSS - 21, for variables that were continuous mean Standard Deviation was calculated and for variables that were categorical frequency percentage were calculated. Results: Total of 87 patients with warfarin toxicity were included. 52 patients (60%) were males & 35 (40%) were females with the mean age of 48.5287 ± 13.1386 years. The factors leading to warfarin toxicity were dietary non-compliance 19 patients (21.83%), drug non-compliance in 18 (20.68%), drug-drug interactions in 12 (13.79%), irregular follow up in 23 (26.39%) and deranged liver functions in 26 (29.88%) patients. Conclusion: Warfarin toxicity has multifactorial causes. Deranged liver functions and irregular follow up of patients accounted for the most prominent factors leading to warfarin toxicity.