Ethnically Diverse Study Finds COVID-19 Increases Risk of Venous Thromboembolism

Thromboembol in blood vessel. Clot formation, 3D illustration
Hospitalized patients with COVID-19 had a greater than 3-fold adjusted risk for venous thromboembolism compared with matched controls, the study found.

An ethnically diverse group of hospitalized patients with COVID-19 had a greater than 3-fold adjusted risk for venous thromboembolism (VTE) compared with matched controls, according to a study recently published in Chest.

A retrospective cohort study was conducted involving 6319 patients with COVID-19 who were hospitalized at 1 of 36 Kaiser Permanente facilities in Northern California or Southern California from February 1 through August 31, 2020, and 6319 patients in a matched control group of hospitalized patients without any evidence of COVID-19.

The researchers sought to explore whether the rate of VTE (deep vein thrombosis or pulmonary embolism) among adults who are hospitalized with COVID-19 differs from that of matched controls without a COVID-19 diagnosis. Laboratory-confirmed COVID-19 was based on polymerase chain reaction (PCR) testing for SARS-CoV-2.

Of the patients included in the study, 46% were women, 53.1% were Hispanic, 14.6% were Asian/Pacific Islander, and 10.3% were Black. Mean patient age was 60.0 ± 17.2 years.

Although both patient groups were similar at baseline, the matched control group was more likely to have cancer and less likely to have sepsis diagnosed during their hospitalization than the patients with COVID-19. Hospitalized patients with COVID-19 were more likely to receive parenteral anticoagulant therapy and to have a higher body mass index, slightly lower median serum creatinine, concentration, and higher hemoglobin and platelet counts compared with matched controls.

The primary study outcome was acute VTE on or after the date of hospital admission. During the 30-day follow-up, a total of 313 cases of validated VTE (160 in those with COVID-19 and 153 among the controls), along with 1172 deaths (817 among patients with COVID-19 and 355 in the controls), were reported, though information on cause of death was unavailable.

Multivariable Fine-Gray regression analysis found that patients with COVID-19 infection had a greater than 3-fold adjusted risk for VTE (adjusted hazard ratio, 3.48; 95% CI, 2.03 to 5.98) compared with matched controls. The Fine-Gray regression accounted for competing risk of death and potential confounders, which included prior VTE, cancer, prior anticoagulant use, body mass index, hemoglobin, platelet count, diagnosed sepsis, and receipt of anticoagulation during the hospitalization or at discharge.

In adult patients with COVID-19, factors predictive of VTE occurrence were: being 55 years of age or older; being Black; diagnosed sepsis; previous VTE; prior moderate or severe hepatic disease; platelet counts of greater than 217 k/mcL; and body mass index ≥40 kg/m2.

The investigators concluded that certain patient characteristics are linked to an elevated risk for VTE in adults with COVID-19 infection. Randomized trials are warranted, to identify safe, effective VTE preventive strategies to be used in patients with COVID-19.

Disclosure: Some of the study authors have declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures. 


Go AS, Reynolds K, Tabada GH, et al. Covid-19 and risk of venous thromboembolism in ethnically diverse populationsChest. Published online July 19, 2021. doi:10.1016/j.chest.2021.07.025