Risk of venous thromboembolism in patients with COVID-19: A systematic review and meta-analysis

Venous thromboembolism (VTE) is frequently observed in patients with coronavirus disease 2019 (COVID-19). However, reported VTE rates differ substantially.

We aimed at evaluating available data and estimating the prevalence of VTE in patients with COVID-19.

We conducted a systematic literature search (MEDLINE, EMBASE, World Health Organization COVID-19 database) to identify studies reporting VTE rates in patients with COVID-19. Studies with suspected high risk of bias were excluded from quantitative synthesis. Pooled outcome rates were obtained within a random effects meta-analysis. Subgroup analyses were performed for different settings (intensive care unit [ICU] vs non-ICU hospitalization and screening vs no screening) and the association of d-dimer levels and VTE risk was explored.

Eighty-six studies (33,970 patients) were identified and 66 (28,173 patients, mean age: 62.6 years, 60.1% men, 19.4% ICU patients) were included in quantitative analysis. The overall VTE prevalence estimate was 14.1% (95% confidence interval [CI], 11.6-16.9), 40.3% (95% CI, 27.0-54.3) with ultrasound screening and 9.5% (95% CI, 7.5-11.7) without screening. Subgroup analysis revealed high heterogeneity, with a VTE prevalence of 7.9% (95% CI, 5.1-11.2) in non-ICU and 22.7% (95% CI, 18.1-27.6) in ICU patients. Prevalence of pulmonary embolism (PE) in non-ICU and ICU patients was 3.5% (95% CI, 2.2-5.1) and 13.7% (95% CI, 10.0-17.9). Patients developing VTE had higher d-dimer levels (weighted mean difference, 3.26 µg/mL; 95% CI, 2.76-3.77) than non-VTE patients.

VTE occurs in 22.7% of patients with COVID-19 in the ICU, but VTE risk is also increased in non-ICU hospitalized patients. Patients developing VTE had higher d-dimer levels. Studies evaluating thromboprophylaxis strategies in patients with COVID-19 are needed to improve prevention of VTE.