Clotting factor levels and COVID-19
Patients who are hospitalized with severe COVID-19 infections and have high levels of the blood-clotting protein factor V are at elevated risk for serious injury from blood clots such as deep vein thrombosis or pulmonary embolism, according to HMS investigators at Massachusetts General Hospital. In addition, patients who are critically ill with COVID-19 and have low levels of factor V appear to be at increased risk for death from a coagulopathy that resembles disseminated intravascular coagulation (DIC), a devastating, often fatal, abnormality in which blood clots form in small vessels throughout the body, leading to an exhaustion of the clotting factors and proteins that control coagulation.
The findings, based on studies of patients with COVID-19 in Mass General intensive care units, indicate that disturbances in factor V activity can be used to identify at-risk patients with the goal of selecting the proper anticoagulation therapy.
In March 2020, the researchers noted that a blood sample from a ventilated patient with COVID-19 contained factor V levels well above the normal reference range. The patient later developed a saddle pulmonary embolism, a potentially fatal blood clot occurring at the junction of the left and right pulmonary arteries.
This observation led investigators to look at the activity of factor V as well as factor VIII and factor X, two other major clotting factors. They studied the levels of these clotting factors and other parameters in 102 consecutive patients with COVID-19 and compared the results with those in contemporaneous critically ill patients without COVID-19, and in historical controls.
They found that, compared with controls, factor V levels were significantly higher among patients with COVID-19 and that the association between high factor V activity and COVID-19 was the strongest among all clinical parameters studied.
In all, 33 percent of patients with factor V activity well above the reference range had either deep vein thrombosis or a pulmonary embolism, compared with only 13 percent of patients with lower levels. Death rates were significantly higher for patients with lower levels of factor V (30 percent vs. 12 percent), with evidence indicating this was due to progression to a DIC-like state.
Stefely J et al., American Journal of Hematology, August 2020