Thrombotic risk in COVID-19: a case series and case-control study

Background A possible association between COVID-19 infection and thrombosis, either as a direct consequence of the virus or as a complication of inflammation, is emerging in the literature. Data on the incidence of venous thromboembolism (VTE) are extremely limited. Methods We describe three cases of thromboembolism refractory to heparin treatment, the incidence of VTE in an inpatient cohort, and a case-control study to identify risk factors associated with VTE. Results We identified 274 confirmed (208) or probable (66) COVID-19 patients. 21 (7.7%) were diagnosed with VTE. D-dimer was elevated in both cases (confirmed VTE) and controls (no confirmed VTE) but higher levels were seen in confirmed VTE cases (4.1 vs 1.2 mu g/mL, p<0.001). Conclusion Incidence of VTE is high in patients hospitalised with COVID-19. Urgent clinical trials are needed to evaluate the role of anticoagulation in COVID-19. Monitoring of D-dimer and anti-factor Xa levels may be beneficial in guiding management.