Blood thinners an effective treatment for many patients with COVID-19.

The award-winning international trial, the REMAP-CAP, led in New Zealand by Dr Colin McArthur, MRINZ researcher and intensive care specialist at Auckland City Hospital, has provided a framework able to evaluate multiple treatment options for critically ill COVID-19 patients.

Early in the COVID-19 pandemic, clinicians around the world observed widespread blood clots and significant inflammation among patients, which led to complications such as lung failure, heart problems and stroke.

Doctors were unsure whether treating such patients with high doses of blood thinners, which would otherwise be given at low doses to reduce blood clots, would be safe and effective.

The REMAP-CAP, an ongoing clinical trial, is the largest worldwide study of treatments for patients critically ill with severe respiratory infections, including COVID-19. The REMAP-CAP randomises patients to receive combinations of treatments, and now involves more than 7000 COVID-19 patients at more than 300 clinical sites around the world, including some ICUs in New Zealand.

Combining with two other trials, the REMAP-CAP assessed the benefit of full doses of blood thinners as preventative treatment for both critically and moderately ill adults hospitalised with COVID-19, compared with a lower dose often used to prevent blood clots in patients in hospital care.

The studies, published in the prestigious New England Journal of Medicine, have found that full doses of blood thinners do not improve outcomes for critically ill patients with COVID- 19, and are likely to be harmful. However, for moderately ill patients, they are beneficial.

With large numbers of COVID-19 patients requiring hospitalisation, this treatment is expected to improve outcomes and reduce the pressure on ICUs around the world.

Dr Colin McArthur says:

“Since early in the pandemic, doctors have been uncertain about how to best provide preventative therapy for blood clotting complications, an important contributor to mortality from COVID-19. These study findings now make it clear that higher doses of blood thinners are beneficial for patients with COVID-19 requiring hospitalisation, but are not beneficial when patients require intensive care-level treatment. Along with other treatments evaluated by the REMAP-CAP study, these results further build our knowledge of how to best treat this disease.”

The MRINZ has played a crucial role in the establishment and running of the REMAP-CAP study through the leadership of Dr Colin McArthur. Adding to New Zealand’s contribution to the ongoing success of the trial is Spiral Web Solutions, based in Wellington, which provides most of the database services for REMAP-CAP.

Professor Richard Beasley, MRINZ Director, says:

“These remarkable study findings will save lives worldwide. It’s a genuinely great achievement that New Zealand has such a strong international leadership role in the REMAP-CAP clinical trials programme that has led to this evidence, thanks in large part to the support of the Health Research Council and the Ministry of Health.

“The dedicated work of Dr McArthur and his team here in New Zealand has contributed to an immense collaborative effort involving patients, clinicians and research staff around the world, enabling us to rapidly learn how best to treat COVID-19. It’s an extremely complicated disease, and we’re discovering so much more about how to best treat patients through these studies.”