Trials Find Full-Dose Blood Thinners May Harm, Not Help, COVID Patients in ICU

WEDNESDAY, Dec. 23, 2020 (HealthDay News) -- Because COVID-19 is known to raise the odds for dangerous blood clots, blood thinners have quickly become part of routine care for many hospitalized patients.

But three clinical trials testing full doses of these drugs in COVID-19 patients have now paused recruitment of critically ill patients because the medications could end up doing more harm than good.

According to experts at the U.S. National Institutes of Health (NIH), the finding is limited to COVID-19 patients who are so sick they require care in the intensive care unit (ICU).

Based on trial findings, and acting on the recommendations of oversight boards that are charged with patient safety in clinical trials, "all the trial sites have paused enrollment of the most critically ill hospitalized patients with COVID-19," the NIH said in a statement released Tuesday.

"Enrollment continues for moderately ill hospitalized COVID-19 patients in the trials," the NIH added, because benefits may still outweigh risks for patients who don't need ICU care.

According to the NIH, results so far from the three trials show that full-dose blood thinners do not appear to lessen the need for organ support in critically ill, adult COVID-19 patients in intensive care.

On the other hand, there could be potential harm: Increased bleeding is a complication of full-dose use of blood thinners.

One doctor on the frontlines of the pandemic agreed that full-dose anticoagulants come with hazards.

"While lower doses of blood thinners may be helpful for both treatment and prevention of blood clots in patients with mild to moderate COVID-19, higher doses may be associated with harm due to increased risk of bleeding —potentially affecting the GI tract, lungs and brain," said Dr. Robert Glatter, an emergency medicine physician at Lenox Hill Hospital in New York City. "Such abnormal bleeding could be lethal if not quickly diagnosed and treated."

Further analyses of the data will be made available as soon as possible, the NIH said.

The three trials are being conducted on four continents. Each compares the use of full doses of blood thinners against the use of lower doses, which are often used to prevent blood clots in hospitalized patients.

These trials were launched because health care providers have noted that many COVID-19 patients, including those who have died from the disease, developed blood clots throughout their bodies, even in their smallest blood vessels. This unusual clotting can cause serious problems such as lung failure, heart attack and stroke, according to the NIH.

"At the recommendation of the oversight boards, patients who do not require ICU care at the time of enrollment will continue to be enrolled in the trial," the NIH said.

"Whether the use of full-dose compared to low-dose blood thinners leads to better outcomes in hospitalized patients with less COVID-19 severe disease remains a very important question. Patients who require full-dose blood thinners for another medical indication are not included in these trials," the NIH noted.

Dr. Teresa Murray Amato is chair of emergency medicine at Long Island Jewish Forest Hills, also in New York City. Responding to the NIH announcement, she said, "As we learn more about the COVID-19 virus, we are continuing to explore medical treatment."

She stressed that full-dose blood thinners might still have a role to play in the care of hospitalized patients who do not need ICU care.

"The study is continuing for less critically ill patients in the hope that we will continue to develop safe and effective treatments," Amato said.

More information

The U.S. Centers for Disease Control and Prevention has more on COVID-19.

SOURCES: Robert Glatter, MD, emergency medicine physician, Lenox Hill Hospital, New York City; Teresa Murray Amato, MD, chair, emergency medicine, Long Island Jewish Forest Hills, New York City; U.S. National Institutes of Health, news release, Dec. 22, 2020