Association between oral anticoagulants and COVID-19-related outcomes: a population-based cohort study
Wong AYS., Tomlinson L., Brown JP., Elson W., Walker AJ., Schultze A., Morton CE., Evans D., Inglesby P., MacKenna B., Bhaskaran K., Rentsch CT., Powell E., Williamson E., Croker R., Bacon S., Hulme W., Bates C., Curtis HJ., Mehrkar A., Cockburn J., McDonald HI., Mathur R., Wing K., Forbes H., Eggo RM., Evans SJW., Smeeth L., Goldacre B., Douglas IJ.
Background Early evidence has shown that anticoagulant reduces the risk of thrombotic events in those infected with COVID-19. However, evidence of the role of routinely prescribed oral anticoagulants (OACs) in COVID-19 outcomes is limited. Aim To investigate the association between OACs and COVID-19 outcomes in those with atrial fibrillation and a CHA2DS2-VASc score of 2. Design and setting On behalf of NHS England, a population-based cohort study was conducted. Method The study used primary care data and pseudonymously-linked SARS-CoV-2 antigen testing data, hospital admissions, and death records from England. Cox regression was used to estimate hazard ratios (HRs) for COVID-19 outcomes comparing people with current OAC use versus non-use, accounting for age, sex, comorbidities, other medications, deprivation, and general practice. Results Of 71 103 people with atrial fibrillation and a CHA2DS2-VASc score of 2, there were 52 832 current OAC users and 18 271 non-users. No difference in risk of being tested for SARS-CoV-2 was associated with current use (adjusted HR [aHR] 0.99, 95% confidence interval [CI] = 0.95 to 1.04) versus non-use. A lower risk of testing positive for SARS-CoV-2 (aHR 0.77, 95% CI = 0.63 to 0.95) and a marginally lower risk of COVID-19- related death (aHR, 0.74, 95% CI = 0.53 to 1.04) were associated with current use versus non-use. Conclusion Among those at low baseline stroke risk, people receiving OACs had a lower risk of testing positive for SARS-CoV-2 and severe COVID-19 outcomes than non-users; this might be explained by a causal effect of OACs in preventing severe COVID-19 outcomes or unmeasured confounding, including more cautious behaviours leading to reduced infection risk.