COVID-19 Patients Face Higher Risk of Dangerous Blood Clots

Researchers using a combination of two specific blood-clotting tests have found that critically ill COVID-19 patients were at a high risk of developing renal failure, venous blood clots, and other complications associated with blood clots, such as stroke.

The study by researchers from the University of Colorado Anschutz Medical Campus (Aurura, CO, USA), which was one of the first to build on growing evidence that COVID-19-infected patients are highly predisposed to developing blood clots, linked blood clotting measurements with actual patient outcomes.


Patients who are critically ill regardless of cause can develop a condition known as disseminated intravascular coagulation (DIC). The blood of these patients initially forms many clots in small blood vessels. The body's natural clotting factors can form too much clot or eventually not be able to effectively form any clot leading to issues of both excessive clotting and excessive bleeding. However, in patients with COVID-19 the clotting appears to be particularly severe and clots in COVID-19 patients do not appear to dissipate, according to Franklin Wright, MD, FACS, lead author of the research article and an assistant professor of surgery at the University of Colorado School of Medicine.

Trauma acute care surgeons and intensive care physicians who treat trauma, transplant, and cardiothoracic surgery patients at UCHealth University of Colorado Hospital used a specialized coagulation test to examine clotting issues in COVID-19 patients. Thromboelastography (TEG) is a whole blood assay that provides a broad picture of how an individual patient's blood forms clots, including how long clotting takes, how strong clots are, and how soon clots break down. TEG is highly specialized and used primarily by surgeons and anesthesiologists to evaluate the efficiency of blood clotting; it is not widely used in other clinical settings.

The researchers evaluated outcomes for all patients who had a TEG assay as part of their treatment for COVID-19 infection as well as other conventional coagulation assays, including ones that measure D-dimer levels. D-dimer is a protein fragment that is produced when a blood clot dissolves. D-dimer levels are elevated when large numbers of clots are breaking down. A total of 44 patients treated for COVID-19 infection between March 22 and April 20 were included in the analysis. Those whose bodies were not breaking down clots most often required hemodialysis and had a higher rate of clots in the veins. These patients were identified by TEG assays showing no clot breakdown after 30 minutes and a D-dimer level greater than 2600 ng/mL. 80% of patients with both affirmative test findings were placed on dialysis compared with 14% who tested for neither finding. Patients with affirmative test findings also had a 50% rate of venous blood clots compared with 0% for those patients with neither finding. The research team is now participating in a randomized clinical trial of a drug that breaks down blood clots in COVID-19-infected patients.

"This is an early step on the road to discovering treatments to prevent some of the complications that come with this disease," Dr. Wright said. "These study results suggest there may be a benefit to early TEG testing in institutions that have the technology to identify COVID-19 patients who may need more aggressive anticoagulation therapy to prevent complications from clot formation."

Related Links:
University of Colorado Anschutz Medical Campus