The RECOVERY Trial, the world’s largest randomised trial of potential COVID-19 treatments, has found that in patients hospitalised with COVID-19, aspirin is not associated with reductions in mortality or in the risk of progressing to invasive mechanical ventilation or death.
In results published on the pre-print server medRxiv, the trial team found that aspirin was associated with a small increase in the rate of being discharged alive.
The RECOVERY trial, which is supported by the NIHR Oxford BRC, was established as a randomised clinical trial to test a range of potential treatments for patients hospitalised with COVID-19. It has recruited almost 40,000 patients across 181 sites.
Patients with COVID-19 are at increased risk of blood clots forming in their blood vessels, particularly in the lungs. Between November 2020 and March 2021, the RECOVERY trial included nearly 15,000 patients hospitalised with COVID-19 in an assessment of the effects of aspirin, which is widely used to reduce blood clotting in other diseases.
A total of 7,351 patients were randomised to aspirin 150 mg once daily and compared with 7,541 patients randomised to usual care alone. There was no evidence that aspirin treatment reduced mortality. There was no significant difference in the primary endpoint of 28-day mortality (17% aspirin versus 17% usual care) and these results were consistent in all pre-specified subgroups of patients.
Patients allocated to aspirin had a slightly shorter median duration of hospitalisation (8 days versus 9 days) and a higher proportion were discharged from hospital alive within 28 days (75% versus 74%)
Among those not on invasive mechanical ventilation at baseline, there was no significant difference in the proportion who progressed to invasive mechanical ventilation or death (21% vs 22%)
For every 1,000 patients treated with aspirin, approximately six more patients experienced a major bleeding event and approximately six fewer experienced a thromboembolic (clotting) event.
Joint Chief Investigator for the RECOVERY trial, Prof Peter Horby of the University of Oxford’s Nuffield Department of Medicine, said: “The data show that in patients hospitalised with COVID-19, aspirin was not associated with reductions in 28-day mortality or in the risk of progressing to invasive mechanical ventilation or death.
“Although aspirin was associated with a small increase in the likelihood of being discharged alive this does not seem to be sufficient to justify its widespread use for patients hospitalised with COVID-19.”
Joint Chief Investigator Prof Martin Landray (left), of the Nuffield Department of Population Health and the Oxford BRC’s Theme Lead for Clinical Informatics and Big Data, added: “There has been a strong suggestion that blood clotting may be responsible for deteriorating lung function and death in patients with severe COVID-19.
“Aspirin is inexpensive and widely used in other diseases to reduce the risk of blood clots so it is disappointing that it did not have a major impact for these patients. This is why large randomised trials are so important: to establish which treatments work and which do not.
“As ever, we are enormously grateful to the thousands of medical staff and patients who have contributed to the RECOVERY trial, helping to find better treatments for patients all around the world.”