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Project #55:
Potentially inappropriate prescribing of DOACs to patients with a mechanical heart valve throughout the COVID-19 pandemic

National guidance was issued during the COVID-19 pandemic to switch patients on warfarin to direct oral anticoagulants (DOACs) where appropriate as these require less frequent blood testing. DOACs are not recommended for patients with mechanical heart valves. We conducted a retrospective cohort study of DOAC prescribing in people with a record of a mechanical heart valve between September 2019 and May 2021, and describe the characteristics of this population. We identified 15,457 individuals with a mechanical heart valve recorded in their records, of whom 1058 (6.8%) had been prescribed a DOAC during the study period. 767 individuals with a record of a mechanical heart valve were currently prescribed a DOAC as of May 31st 2021.


  • Study lead: Louis Fisher
  • Organisation: University of Oxford and London School of Hygiene and Tropical Medicine
  • Project type: Research
  • Topic area: Other/indirect impacts of COVID on health/healthcare
  • Code on GitHub: opensafely/mechanical-valve-anticoag