In April 2020, the government announced a lockdown during the COVID-19 pandemic. Most patients with chronic diseases had their appointment postponed. However, individuals who were taking warfarin, due to uncertainty about the efficacy and safety of the drug, were an exception. This study was conducted to measure the effects of such circumstances.
Objectives: To compare the time in therapeutic range (TTR) and the incidence of severe bleeding before and during the COVID-19 pandemic.
Materials and methods: An observational study was conducted in patients receiving warfarin pre-epidemic period (October 2019 to March 2020) at the 9th Health Area Network Hospital, had at least 2 INR (International Normalized Ratio), and received a consistent warfarin dosage. Subsequently, follow-up INR levels and incidents of severe bleeding during the COVID-19 period (April to August 2020).
Results: There were 1,175 eligible patients with total 7,504 follow-up times in this study. A significantly decreased in TTR during the pandemic was observed (70.00 ± 29.22% and 59.03 ± 35.22%; p< 0.001). The number of major bleeding events was significantly increased (0/100 person-years and 1.08/100 person-years; p<0.001). It was observed that INR >4.5 increased from 60 times (1.37%) to 88 times (2.66%). Additionally, the number of warfarin dose adjustments significantly increased (0 time and 492 times). Meanwhile, the interval between appointments decreased (36.20 ± 8.48 days and 31.99 ± 9.95 days).
Conclusion: The efficacy of warfarin use has decreased compared to before the outbreak and more serious bleeding complications were identified. The follow-up period was more frequent than usual. This could be out-of-range INR values, necessitating more frequent warfarin adjustment appointments. However, further studies should be conducted on factors which influence TTR, such as gender, age range, and concomitant medications. This will help in considering the possibility of postponing appointments with drug efficacy.