Blood thinners help patients treated with moderate cases of COVID-19 but not those who are seriously ill, a new study suggests.

Researchers at the National Heart, Lung, and Blood Institute (NHLBI), part of the National Institutes of Health, examined more than 5,500 hospital patients infected with the virus.

They found that a full-dose anticoagulant reduced the need for organ support for moderately ill patients and improved their chances of discharge from hospital.

However, critically ill COVID-19 patients in intensive care did not have the same results when they received this treatment.

“These results are a compelling example of the importance of stratifying patients with different disease severities in clinical trials,” Dr. Gary Gibbons, director of the NHLBI, said in a statement.

“What might help one subset of patients might be of no benefit or even harm in another.”

At the start of the pandemic, doctors noticed a growing number of coronavirus patients with blood clots, either in their feet – which cause bruises known as “COVID toes” – or blockages in the brain. that lead to stroke or death.

Previous studies in the Netherlands and France have found that up to a third of critically ill COVID-19 patients have experienced pulmonary embolism.

It happens when blood clots travel to the lungs, causing a threatening blockage in the arteries.

Therefore, some researchers believe that blood thinners might prevent fatal blood clots from forming, but are unsure at what dose or at what stage of infection they might be effective.

For the study, published in the New England Journal of Medicine, the team looked at 1,074 critically ill patients and 2,219 moderately ill patients.

Moderately ill patients were defined as those who were hospitalized but did not require organ support, while critically ill patients were defined as hospitalized and requiring intensive care.

In April 2020, patients were given either a low dose or a full dose of heparin, which prevents blood clots from forming.

The researchers looked at the results through December 2020.

They found that it reduced the need for organ support like mechanical ventilation for moderately ill patients by 99% compared to those who received low doses.

For critically ill patients, the full dose did not reduce the need for organ support or increase their

“The formal findings of these studies suggest that initiation of therapeutic anticoagulation is beneficial for moderately ill patients and once patients develop severe COVID-19, it may be too late for anticoagulation to occur. heparin alters the consequences of this disease, ”said corresponding author, Dr. Judith. Hochman, Senior Associate Dean for Clinical Sciences at New York University.

“The drug evaluated in these trials is familiar to physicians around the world and is widely available, making the results highly applicable to moderately ill COVID-19 patients.”