Anticoagulation in COVID-19 patients - An updated systematic review and meta-analysis

Abstract

Background: Thromboembolic events are common complications of COVID-19. Clinical study results on safety and efficacy of anticoagulation in COVID-19 are controversial.

Material and methods: This report is the second update of our systematic review with meta-analysis on randomized controlled trials (RCTs) comparing standard thromboprophylaxis, intermediate or therapeutic dose anticoagulation or no anticoagulation in COVID-19 in- and outpatients. We searched eligible studies up to 5 October 2023. Certainty of evidence was assessed using GRADE.

Results: For this update we included fourteen new RCTs and a total of 27 RCTs with 16,789 patients. Certainty of evidence ranged from very low to high depending on outcome and comparison. Standard thromboprophylaxis with low dose anticoagulation may have little or no effect for COVID-19 outpatients compared to no anticoagulation. In inpatients with moderate or severe COVID-19, intermediate dose anticoagulation may decrease any thrombotic events or death, but may increase major bleeding compared to standard thromboprophylaxis. Therapeutic dose anticoagulation decreases thrombotic events or deaths in inpatients with moderate COVID-19, but probably has little or no effect in patients with severe COVID-19 compared to standard thromboprophylaxis with low or intermediate dose anticoagulation. With therapeutic dose anticoagulation, the risk of major bleeding probably increases regardless of COVID-19 severity. We are uncertain on the effect of thromboprophylaxis with low dose anticoagulation compared to no anticoagulation in the post-discharge setting.

Conclusions: Hospitalized, moderately-ill COVID-19 patients may benefit from intermediate or therapeutic dose anticoagulation, while critically ill patients may not. Risk of major bleeding must be considered.

Keywords: Anticoagulant therapy; Bleeding; COVID-19; Systematic review; Thrombosis.