CLARITY on a clinically controversial question for the treatment of COVID-19


Results for the COVID-19 clinical trial CLARITY, led by a collaboration between the NHMRC Clinical Trials Centre at the University of Sydney and The George Institute for Global Health (India, Australia, and the UK), have been published today in BMJ. They show that the addition of a common blood pressure treatment does not improve outcomes in patients hospitalised with mild COVID-19.

CLARITY evaluated whether a widely used blood pressure medication class called angiotensin receptor blockers (ARBs), is effective in reducing severity of infection with COVID-19. The trial recruited 787 participants from 17 hospitals in India & Australia. Participants were at least 18 years old, not already receiving angiotensin receptor blockers, with a confirmed diagnosis of SARS-CoV-2 infection and admitted to hospital for management of COVID-19.

At the start of the pandemic there were competing theories on whether ARBs would improve or worsen COVID-19 disease based on what was known of how the virus interacted with the body’s cells. The controversy had implications that went beyond the treatment of COVID as ARBs have been proven to help long term protection in people at risk of heart and kidney disease. The uncertainty led to some calls to cease ARBs in case individuals contracted COVID-19 which would come at the cost of losing the long term protective benefits.

“The results from the CLARITY trial have given us the answer to a clinically controversial question,” says study chair Professor Meg Jardine, Director of the NHMRC Clinical Trials Centre (CTC) at the University of Sydney. “We now know that the use of angiotensin receptor blockers is not beneficial in people admitted to hospital for COVID-19 with low disease severity compared with placebo or standard of care. At the same time, we didn’t see compelling reasons to stop ARB treatment where it is indicated for other reasons.”


An innovative approach in response to the pandemic

The CLARITY trial was designed to accommodate the complexities of running a clinical trial during a pandemic. “CLARITY used pragmatic approaches to research delivery. By embedding the simple trial into standard clinical care processes, and leveraging the available routinely collected data, we could ensure low site and patient burden in research delivery.” explains Program Manager Arlen Wilcox. “Appropriate use of innovative methods, like CLARITYs adaptive sample size, ensured the study’s high quality evidence was generated most efficiently.”

Features of the pragmatic trial design included:

  • Use of verbal, witnessed or e-consent rather than paper-based consent from participants reduced contamination risk
  • Minimised trial specific face-to-face encounters. Trial requirements met through routine health care encounters
  • Use of routine clinical data from medical records
  • Medication dose levels left to the discretion of the treating clinician
  • Collaborative leadership model meant trial conducted where case burden was highest


A success story for international collaboration

“CLARITY has been a success story for international collaboration during the challenging conditions of the pandemic,” reflects Study Co-Chair, Professor Jha, Director of The George Institute, India. “The teams in India and Australia came together at short notice and worked really well together, sharing their expertise and knowledge.”

The next step for the team is to collaborate with leaders of other similar trials to maximise understanding in this area. Professor Meg Jardine comments, “There are a few other trials that have asked similar questions, some of which could not be completed, and some are yet to complete. We are now collaborating with the leaders of other trials to ensure we have maximum understanding from the combined research effort and ensure the contribution made by individual participants in these trials is recognised.”


Read paper in BMJ >


Story by Sarah Munro, Communications Officer (NHMRC Clinical Trials Centre, The University of Sydney)