Study Reports on Thrombotic Rates Among COVID-19 Patients

Stephanie Berg, DO

Findings from a retrospective analysis reported a 7.5% prevalence of thrombotic events among coronavirus disease 2019 (COVID-19) patients. The study was conducted at 3 university health systems in the Chicago Metropolitan Area.

The investigators also evaluated and identified risk factors for thrombosis.

The study, presented at the American Society of Hematology (ASH) 2020 Conference, was led by Stephanie Berg, DO, Division of Hematology and Oncology, Loyola University Medical Center, and was conducted between March 2020 – May 2020.

The health systems included were the Loyola University Health System (LUHS), Rush University System for Health (RUSH), and University of Illinois-Chicago (UIC).

All patients (n = 2180) evaluated were admitted to the hospital for COVID-19. The investigators confirmed pulmonary embolism, deep-vein thrombosis, or arterial thrombosis through supportive imaging modalities.

For their analyses, they used Wilcoxon rank sum test to test the associations of continuous variables as well as Chi-square test or Fisher’s exact test to evaluate the associations of categorical variables.

Overall, they assessed a total of 2180 patients across the 3 hospital systems.

Hispanics represented 47% of patients at LUHS, 32% at RUSH, and 36% at UIC. Additionally, African Americans represented 17%, 42%, and 51%, respectively.

Of the overall population, 33% were admitted for intensive care.

A Report of Thrombotic Event Patterns Across the Hospital Systems

In terms of total thrombotic events, LUHS reported 5.4% events. Of this amount, 41 patients were reported with venous thromboembolism and pulmonary embolism, 10 with arterial thrombosis, and 5 with both venous and arterial embolism. 

RUSH reported 9.7% of thrombotic events, with 70 being classified venous thromboembolism and pulmonary embolism, 7 arterial embolism, and 4 with both venous and arterial embolism.

And finally, UIC reported a 6% rate. Of this, 14 were venous thromboembolism and pulmonary embolism, 4 were pulmonary, and none were both venous and arterial.

Berg and team noted that patients age, sex, and BMI did not differ among patients that developed a thrombotic event.

They also reported that anticoagulation prophylaxis was given to 82% of patients the LUHS and UIC at time of admission.

“Collectively, those with thrombotic events (N = 156) had higher incidence of intensive care admission, elevated white blood cell count and a d-dimer >5X upper limit normal, at presentation,” they wrote. “Furthermore, a higher proportion of patients that had a thrombotic event were diabetic at LUHS and RUSH.”

They further explained that the mortality rate in all COVID-19 patients was 13-16%. However, patients in with a thrombotic event in RUSH and UIC were noted to have an increased risk of death.

The team indicated that future studies will aim to explore the mortality differences and anticoagulation practices between the institutions as well as race/ethnicity differences in thrombosis events.

“Finally, based off these risk factors, identification of patients at most risk for thrombosis is needed to reduce the morbidity and mortality when diagnosed with COVID-19,” Berg and team concluded.

The study, “Real World Outcomes of Sars-Cov-2 Thrombosis Rates across Three University Health Systems in the Chicago Metropolitan Area,” was presented at ASH 2020.