Time in Therapeutic Range and Adverse Outcomes among Patients Receiving Warfarin Therapy at Tertiary Care Hospital

Background Warfarin has a narrow therapeutic index and needs regular international normalized ratio monitoring and dose adjustment. Poor quality of warfarin dosing can lead to an increased risk of adverse events. Objective To find out the overall quality of the international normalized ratio expressed in terms of time in therapeutic range and adverse outcomes associated with the use of warfarin. Method A descriptive cross-sectional study among 150 patients attending a tertiary care center receiving warfarin therapy from December 2022 to June 2023. Patients receiving warfarin at least for 6 months and with at least three international normalized ratio values were enrolled. Indications, average daily dosing, international normalized ratio, and adverse effects were recorded using convenient sampling. Data were analyzed by using SPSS, version 20. Result The mean age was 46.41±13.96 years. Indications for warfarin were valvular and nonvalvular atrial fibrillation in 104 (69.33%), deep vein thrombosis 21 (14%), and pulmonary embolism 6 (4%). The majority of patients 100 (66.6%) received 5 to 10mg of warfarin per day. The mean duration of warfarin use was 18.11±21.93 months. The mean time in the therapeutic range (%) was 62.43±27.52. Sixty patients (40%) had time in the therapeutic range below 60%. Among the adverse effects, minor bleeding was present in 25 (16.66%). The ischemic event was present in 7 (4.7%). Conclusion Our patients had lower time in the therapeutic range than recommended in the guidelines. They had a longer time in the sub-therapeutic range.