Are Inpatients With COVID-19 at Higher Risk of Venous Thromboembolism?

Thromboembol in blood vessel. Clot formation, 3D illustration
Is VTE risk unusually high in patients with COVID-19? To find out, researchers compared VTE incidence in inpatients with COVID-19 vs those with CAP.

Patients hospitalized for COVID-19 have a higher incidence of venous thromboembolism (VTE) than those admitted due to community-acquired pneumonia (CAP), according to a study recently published in the Annals of the American Thoracic Society.

Several studies have suggested that COVID-19 is associated with an increased prevalence of venous thromboembolism, with a meta-analysis indicating an overall incidence of 17%; however, “comparative data is lacking,” said investigators for the current study. To address this, the investigators compared rates of VTE and VTE testing among inpatients with COVID-19 vs inpatients with CAP.  This retrospective cohort study included all patients admitted to the 23 hospitals of the Intermountain Health Care System in the Western US between January 1 and December 31, 2020. For the study cohort, the researchers searched records for patients who had a positive SARS-CoV-2 test 7 days before through 90 days after admission. The control group consisted of patients at 16 of the 23 participating hospitals receiving a diagnosis of CAP from January 1, 2017 to June 20, 2019. To evaluate for VTE, lower extremity (LE) Doppler ultrasound, ventilation/perfusion scan, or computed tomography pulmonary angiogram (CTPA) were performed as indicated 7 days before through 90 days after the index admission date.

A total of 7509 COVID-19 patients (mean age 57 years; 50% female) were compared with 4304 CAP patients (mean age 67 years; 48% female). In all, 38% of patients with COVID-19 and 43% of patients with CAP underwent VTE testing (P =.992; adjusted odds ratio [OR], 1.00). Of the COVID-19 patients, 6.2% tested positive for VTE, whereas 4.0% of patients with CAP did so (P <.00001; adjusted OR, 1.64). The positivity rate for COVID-19 patients tested for VTE was 16.3%, and that of CAP patients tested for VTE was 9.2%. The rate of positive CTPA among COVID-19 patients was 3.2%, compared with 1.7% for CAP patients (P <.00001; adjusted OR, 1.99). Among COVID-19 patients, the rate of positive LE Doppler testing was 3.3%, vs 2.5% for CAP patients (P =.008; adjusted OR, 1.40).

The investigators saw a higher rate of VTE in COVID-19 patients than in patients with a diagnosis of CAP. Notably, the rate of testing for VTE did not differ between these 2 patient cohorts. The researchers also perceived a higher incidence of pulmonary embolism and deep vein thrombosis among those with a COVID-19 diagnosis. These observations support earlier studies reporting that COVID-19 infection is uniquely thrombogenic in hospitalized patients.

Several factors created limitations to this study. The VTE studies were interpreted by radiologists from the Intermountain System, who may have been influenced by published reports of high rates of VTE among COVID-19 patients and who were not blinded to the COVID-19 status of the patients. Selection bias regarding which patients were chosen for diagnostic testing is inherent in this study.

“Our estimates may still be under-estimates of the true incidence of VTE in COVID-19,” said investigators, given that a higher level of testing was not done in patients with COVID-19, even though more testing was likely warranted. “Of the patients with COVID-19 tested for VTE, 16.3% were positive which is above previously reported positivity rate of 5% among all inpatients indicating testing is likely not done frequently enough for COVID-19 patients and there may be missed opportunities to diagnose and treat patients for VTE,” they added.


Hendrickson KW, Knox DB, Bledsoe JR, et al. Comparative frequency of venous thromboembolism in patients admitted to the hospital with SARS-CoV-2 infection vs. community-acquired pneumonia. Ann Am Thorac Soc. Published online March 2, 2022. doi:10.1513/AnnalsATS.202108-953RL

This article originally appeared on Pulmonology Advisor