OpenSAFELY: impact of national guidance on switching from warfarin to direct oral anticoagulants (DOACs) in early phase of COVID-19 pandemic in England

  1. The OpenSAFELY Collaborative
  2. Helen J Curtis
  3. Brian MacKenna
  4. Alex J Walker
  5. Richard Croker
  6. Amir Mehrkar
  7. Caroline E Morton
  8. Seb Bacon
  9. George Hickman
  10. Peter Inglesby
  11. Chris Bates
  12. David Evans
  13. Tom Ward
  14. Jonathan Cockburn
  15. Simon Davy
  16. Krishnan Bhaskaran
  17. Anna Schultze
  18. Christopher T Rentsch
  19. Elizabeth Williamson
  20. William Hulme
  21. Helen I McDonald
  22. Laurie Tomlinson
  23. Rohini Mathur
  24. Henry Drysdale
  25. Rosalind M Eggo
  26. Kevin Wing
  27. Angel YS Wong
  28. Harriet Forbes
  29. John Parry
  30. Frank Hester
  31. Sam Harper
  32. Stephen JW Evans
  33. Ian J Douglas
  34. Liam Smeeth
  35. Ben Goldacre
1 evaluations Published on
Read the full article Related papers
This article on Sciety

Abstract

Background

Early in the COVID-19 pandemic the NHS recommended that appropriate patients anticoagulated with warfarin should be switched to direct acting oral anticoagulants (DOACs), requiring less frequent blood testing. Subsequently, a national safety alert was issued regarding patients being inappropriately co-prescribed two anticoagulants following a medication change, and associated monitoring.

Objective

To describe which people were switched from warfarin to DOACs; identify potentially unsafe co-prescribing of anticoagulants; and assess whether abnormal clotting results have become more frequent during the pandemic.

Methods

Working on behalf of NHS England we conducted a population cohort based study using routine clinical data from >17 million adults in England.

Results

20,000 of 164,000 warfarin patients (12.2%) switched to DOACs between March and May 2020, most commonly to edoxaban and apixaban. Factors associated with switching included: older age, recent renal function test, higher number of recent INR tests recorded, atrial fibrillation diagnosis and care home residency. There was a sharp rise in co-prescribing of warfarin and DOACs from typically 50-100 per month to 246 in April 2020, 0.06% of all people receiving a DOAC or warfarin. INR testing fell by 14% to 506.8 patients tested per 1000 warfarin patients each month. We observed a very small increase in elevated INRs (n=470) during April compared with January (n=420).

Conclusions

Increased switching of anticoagulants from warfarin to DOACs was observed at the outset of the COVID-19 pandemic in England following national guidance. There was a small but substantial number of people co-prescribed warfarin and DOACs during this period. Despite a national safety alert on the issue, a widespread rise in elevated INR test results was not found. Primary care has responded rapidly to changes in patient care during the COVID-19 pandemic.

Related articles

Related articles are currently not available for this article.