Trial of Excessive-Dose Blood Thinners in I.C.U. Sufferers Is Halted

A large study with high-dose blood thinners in critically ill Covid-19 patients in the hospital is temporarily canceled because the treatment appears to be of no benefit and possibly causes harm, the heads of the study announced on Tuesday.

The independent monitoring body that called for the trial to be interrupted did not disclose what potential harm it had found. High doses of anticoagulants are known to cause uncontrollable bleeding – in places, including the inside of the skull, that can be very dangerous.

The leaders of the study are urgently trying to get the message across that the study has been suspended because some hospitals are still aggressively treating their ICU patients with high doses of anticoagulants, believing that the benefits outweigh the risks while the opposite is true can.

“We need to make this pause in the study widely known because of the potential harm,” said Dr. Matthew D. Neal, surgeon and critical care specialist at the University of Pittsburgh Medical Center, who is leading one of many teams in the trial.

The teams in the study, which enrolled approximately 3,000 patients in multiple countries, will closely examine the data to see if enrollment in the branch of the study, which focuses on critically ill hospital patients, can begin again.

It is well known that Covid-19 causes clusters of small blood clots that block capillaries and can cause damage to the lungs, kidney, heart, brain or other organs and even fingers and toes. Low doses of blood thinners are routinely given to hospitalized Covid-19 patients as soon as they are admitted, said Dr. Neal.

The branch of the study of giving high doses of blood thinners to patients who are moderately ill will continue.

Moderately ill patients generally include those who are receiving oxygen but are not in intensive care, are not ventilated, or are at risk of other organs such as the kidneys failing.

In October, an observational study in the Journal of the American College of Cardiology found that hospitalized Covid-19 patients who were given blood thinners did much better than those who weren’t. In this study, there was little difference in results or negative side effects between those given low or high doses.

Based in part on this study, many doctors believed that the sickest patients should be given the largest doses when a certain amount of anticoagulant is good for most patients, said Dr. Jeffrey S. Berger, director of the Center for the Prevention of Cardiovascular Disease at New York University Medical School, and another senior investigator in the paused study.

Updated

Apr. 21, 2020, 6:49 am ET

“Hopefully this will be humiliating,” said Dr. Berger on the new evidence that large doses could be harmful. “It helps us realize that we don’t have all the answers.”

Anticoagulants are known to cause bleeding under the skin and into the gastrointestinal tract and wounds that do not heal if the skin is pierced.

Bleeding within the skull is rare but can cause permanent brain damage or death, noted Dr. Berger.

Dr. Neal said he had treated Covid victims “with problems on both ends of the spectrum: patients with blood clots and patients with bleeding”.

According to Dr. For Neal, one of the aims of the study was to find out which patients are most likely to benefit from anticoagulants.

Patients are often tested for D-dimer, a breakdown product of blood clots, and for C-reactive protein, a marker of inflammation that may be associated with clotting. It would be useful to know, said Dr. Neal, whether these tests could accurately predict which patients would receive the most benefit from high doses of anticoagulants.

The interrupted study is a large, coordinated effort by what was once three separate clinical study groups in multiple countries. It is jointly funded by the National Institutes of Health and their counterparts in Canada, the United Kingdom, Australia and the European Union.

“This is the most collaborative thing I’ve been involved in in my entire time in medicine,” said Dr. Neal.

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