Factors Linked to Venous Thromboembolism in Patients With Severe COVID-19

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Patients who are critically ill with COVID-19 are at high risk for venous thromboembolism (VTE) and bleeding, according to the results of a study published in the Clinical Respiratory Journal.

Researchers conducted a single-center, retrospective study to assess the risk of in-hospital VTE and bleeding in 138 patients with COVID-19 (58.7% male, average age 52.43 ± 16.68 years) at the Shanghai Public Health Clinical Center in Shanghai, China, from January to February in 2020. Of these, 15 patients (10.9%) were critically ill and 56 (40.6%) had comorbidities. Critically ill patients were significantly older (60.07 ± 14.25 years vs 50.52 ± 15.97 years; P <.01), were more likely to have comorbidities, and had higher D-dimer levels. The Padua Prediction Score and the Improve bleed model assessment were used to analyze the risk. Risk factors were evaluated based on admission data, with further evaluations conducted if the patient’s situation changed with respect to VTE and bleeding risk.

The investigators found that 16.7% of the entire patient cohort were at increased risk of VTE per the Padua prediction score and that 6.5% were at increased risk of bleeding secondary to VTE prophylaxis per the Improve prediction score. However, those risks varied tremendously between those patients with COVID-19 who were critically ill vs those who were not.

With respect to VTE, the analysis revealed that 115 (83.3%) patients were at low risk for VTE (Padua score <4) and 23 (16.7%) patients were at high risk for VTE (Padua score ≥4). Additionally, VTE was more common among patients who were critically ill vs those who were not (15 [100%] vs  7 [6.5%], respectively; P <.01). Compared with patients without critical illness, those who were critically ill were more likely to have VTE risk factors that included reduced mobility (15 [100.0%] vs 6 [5.0%], respectively; P <.001); elderly age (7 [46.7%] vs 10 [8.3%], respectively; P <.001); respiratory failure (11 [73.3] vs 44 [36.4%], respectively; P <.01); and obesity (2 [13.3%] vs 0 [0%], respectively, P =.01).

With respect to bleeding, the analysis revealed a high risk for bleeding among patients who were critically ill vs those who were not (9 [60.0%] vs 0 [0%], respectively; P <.01). The researchers noted thrombotic events in 4 (2.9%) of patients, with diagnosis of deep vein thrombosis made in all these patients by ultrasound between 3 and 18 days following admission. Of these 4 patients, 3 were critically ill. One major hemorrhage occurred during VTE treatment in a critically ill patient.

Overall, the researchers found that the 15 patients with COVID-19 who were critically ill faced high risk from thrombosis and hemorrhage. “More effective VTE prevention strategies based on an individual assessment of bleeding risks were necessary for critically ill patients with COVID-19,” the investigators noted.

Limitations of the current study include its limited sample size and retrospective nature. The authors stressed the need for a prospective study with a larger cohort to better elucidate VTE risk as well as hemorrhage complications during thromoprophylaxis.


Wang L, Zhao L, Li F, et al. Risk assessment of venous thromboembolism and bleeding in COVID-19 patients. Clin Respir J. Published on January 21, 2022. doi:10.1111/crj.13467