During the Covid-19 pandemic, four patients were admitted to a healthcare centre. They were treated with vitamin K antagonists (AVK). We observed a substantial increase in their International Normalised Ratio (INR). The mean age of these patients was 90 (± 8 years). All had different usual long-term therapy treatments but had fixed doses of AVK to reach a stable INR. No changes to the background regimen were implemented. One patient presented a cough whereas the three others were asymptomatic. In the context of the pandemic, a reverse transcriptase polymerase chain reaction (RT-PCR) for SARS-CoV-2 was carried out for each patient. The results of the RT-PCR rests were all positive and were associated with a substantially increased INR. Mr H. was admitted with an INR of 2.25 which increased to 5.93 the day after RT-PCR positivity. AVK treatment was stopped but the INR one day after was 7.89. Ms J. presented INR values between 1.96 and 4.58, 10 days later. a PCR test was conducted and AVK treatment was stopped, but the INR still increased to 5.85. The INR of Mr R. increased from 1.82 to 8.05, 24 hours after a positive PCR result. Ms F. presented a gradual increase in INR from 1.5 to 3.36, 72 hours after a positive PCR result and three days after discontinuation of AVK. This study suggest a link between the Covid-19 infection and an increased INR. It has been established that SARS-CoV-2 infection induces hypercoagulability in severe forms. Inversely, these four cases show a haemorrhagic risk as the INR increases. There could be a risk of overdose when patients are treated with AVK and are positive for Covid-19. This raises the question of discontinuing AVK and substituting it with another anticoagulant, or performing INR checks more frequently in the context of Covid-19. Moreover, an unexpected increase in INR should indicate the need to conduct a Covid-19 RT-PCR test in the context of this pandemic context.
Keywords: AVK; INR; PCR; SARS-CoV-2.