Paper information
- Authors
-
- Angel Wong,
- Laurie Tomlinson,
- Jeremy Brown,
- William Elson,
- Alex Walker,
- Anna Schultze,
- Caroline Morton,
- Dave Evans,
- Peter Inglesby,
- Brian MacKenna,
- Krishnan Bhaskaran,
- Christopher Rentsch,
- Emma Powell,
- Elizabeth Williamson,
- Richard Croker,
- Seb Bacon,
- Will Hulme,
- Chris Bates,
- Helen Curtis,
- Amir Mehrkar,
- Jonathan Cockburn,
- Helen McDonald,
- Rohini Mathur,
- Kevin Wing,
- Harriet Forbes,
- Rosalind Eggo,
- Stephen Evans,
- Liam Smeeth,
- Ben Goldacre,
- Ian Douglas
- Citation
- The OpenSAFELY Collaborative., Wong, A.Y.S., Tomlinson, L.A. et al. Association between warfarin and COVID-19-related outcomes compared with direct oral anticoagulants: population-based cohort study. J Hematol Oncol 14, 172 (2021). https://doi.org/10.1186/s13045-021-01185-0
- Categories
Abstract
Background
Thromboembolism has been reported as a consequence of severe COVID-19. Although warfarin is a commonly used anticoagulant, it acts by antagonising vitamin K, which is low in patients with severe COVID-19. To date, the clinical evidence on the impact of regular use of warfarin on COVID-19-related thromboembolism is lacking.
Methods
On behalf of NHS England, we conducted a population-based cohort study investigating the association between warfarin and COVID-19 outcomes compared with direct oral anticoagulants (DOACs). We used the OpenSAFELY platform to analyse primary care data and pseudonymously linked SARS-CoV-2 antigen testing data, hospital admissions and death records from England. We used Cox regression to estimate hazard ratios (HRs) for COVID-19-related outcomes comparing warfarin with DOACs in people with non-valvular atrial fibrillation. We also conducted negative control outcome analyses (being tested for SARS-CoV-2 and non-COVID-19 death) to assess the potential impact of confounding.
Results
A total of 92,339 warfarin users and 280,407 DOAC users were included. We observed a lower risk of all outcomes associated with warfarin versus DOACs [testing positive for SARS-CoV-2, HR 0.73 (95% CI 0.68–0.79); COVID-19-related hospital admission, HR 0.75 (95% CI 0.68–0.83); COVID-19-related deaths, HR 0.74 (95% CI 0.66–0.83)]. A lower risk of negative control outcomes associated with warfarin versus DOACs was also observed [being tested for SARS-CoV-2, HR 0.80 (95% CI 0.79–0.81); non-COVID-19 deaths, HR 0.79 (95% CI 0.76–0.83)].
Conclusions
Overall, this study shows no evidence of harmful effects of warfarin on severe COVID-19 disease.