High-dose versus low-dose venous thromboprophylaxis in hospitalized patients with COVID-19: a systematic review and meta-analysis

Background: Hospitalized COVID-19 patients are at high risk of venous thromboembolism (VTE). Standard doses of anticoagulant prophylaxis may not be sufficiently effective for the prevention of VTE. The objective of this systematic-review and meta-analysis was to compare the efficacy and safety of high-dose versus low-dose thromboprophylaxis in hospitalized patients with COVID-19. Material and methods: MEDLINE and EMBASE were searched up to October 2021 for randomized clinical trials (RCTs) comparing high-dose with low-dose thromboprophylaxis in hospitalized adult patients with COVID-19. The primary efficacy outcome was the occurrence of VTE and the primary safety outcome was major bleeding. Results: A total of 5470 patients from 9 RCTs were included. Four trials included critically ill patients, four non-critically ill patients, and one included both. VTE occurred in 2.9% of patients on high-dose and in 5.7% of patients on low-dose thromboprophylaxis (relative risk [RR] 0.53; 95% confidence intervals [CIs], 0.41–0.69; I2 = 0%; number needed to treat for an additional beneficial outcome, 22). Major bleeding occurred in 2.5% and 1.4% of patients, respectively (RR 1.78; 95% CI, 1.20–2.66; I2 = 0%; number needed to treat for an additional harmful outcome, 100). All-cause mortality did not differ between groups (RR 0.97; 95% CI, 0.75–1.26; I2 = 47%). The risk of VTE was significantly reduced by high-dose thromboprophylaxis in non-critically ill (RR 0.54; 95% CI, 0.35–0.86; I2 = 0%), but not in critically ill patients (RR 0.69; 95% CI, 0.39–1.21; I2 = 36%). Discussion: In hospitalized patients with COVID-19, high-dose thromboprophylaxis is more effective than low-dose for the prevention of VTE but increases the risk of major bleeding.