The effect of COVID-19 pandemic on time in therapeutic range in patients using warfarin

ABSTRACT

Introduction: Patients receiving anticoagulant therapy experience a serious problem at a time when the rates of outpatient visits for the international normalized ratio (INR) monitoring are gradually decreasing owing to the risk of virus transmission during the pandemic. The aim of this multicenter study was to investigate how the coronavirus disease 2019 pandemic affected the time in therapeutic range (TTR) value, which shows the use of effective doses of warfarin, and its monitoring in patients using warfarin. Materials and Methods: A total of 158 patients with 3 consecutive prepandemic INR levels and at least 3 postpandemic INR levels without time limitation were retrospectively evaluated. TTR values were calculated and the preepidemic and postepidemic values were compared. TTR was obtained using the conventional method. Results: The mean preepidemic and postepidemic TTR values were found to be 64.4 (61.8%-67.0%) and 34.9 (30.8%-39.0%), respectively. TTR rate was statistically significantly lower in the postpandemic period than in the prepandemic period (P < 0.001). While the prepandemic TTR of 68 (43%) patients was <60, the postpandemic TTR of 125 (79%) patients was <60. Discussion and Conclusion: Patients using warfarin were found to have lower TTR values during the pandemic. One of the most important reasons for this result is patients' delayed admission to the hospital due to fear of infection. The importance of regular follow-ups and alternative solutions should be emphasized for the effective treatment of these patients.