Venous thromboembolism in COVID-19 compared to non-COVID-19 cohorts: A systematic review with meta-analysis

Background: Many studies confirmed an association between COVID-19 and venous thromboembolism (VTE). Whether the risk of VTE significantly differed between COVID-19 cohorts and non-COVID-19 cohorts with similar disease severity remains unknown. Objectives: The aim of this systematic review with meta-analysis was to compare the rate of VTE between COVID19 and non-COVID-19 cohorts with similar disease severity. Methods: A systematic literature search (MEDLINE, Embase and Google Scholar) was conducted from January 1, 2020 to March 31, 2021 to identify studies reporting VTE in COVID-19. Relative risks (RR) were estimated for the effect measure with 95% confidence intervals. Results: Seven studies (41,768 patients) evaluated VTE in COVID-19 cohorts compared to non-COVID-19 cohorts. The overall risk of VTE (RR 1.18; 95%CI 0.79-1.77; p = 0.42; I2 = 54%), pulmonary embolism (RR 1.25; 95%CI 0.77-2.03; p = 0.36; I2 = 52%) and deep venous thrombosis (RR 0.92; 95%CI 0.52-1.65; p = 0.78; I2 = 0%) did not significantly differ between COVID-19 and non-COVID-19 cohorts. However, subgroup analyses suggested an increased risk of VTE amongst CODID-19 versus non COVID-19 cohorts when only patients hospitalized within the intensive care unit (ICU) were considered (RR 3.10; 95%CI 1.54-6.23), which was not observed in cohorts of predominantly non-ICU patients (RR 0.95; 95%CI 0.81-1.11) (Pinteraction = 0.001). Conclusion: There was no signal for a difference in VTE in COVID-19 cohorts compared to non-COVID-19 cohorts, except for the subgroup of patients hospitalized in the ICU. These results should be viewed as exploratory and further studies are needed to confirm these results.