Aim: Coronavirus disease 2019 (COVID-19) has been associated with increased mortality and morbidity from thromboembolism, especially venous thromboembolism. There are more limited data for systemic thromboembolism. The present study aimed to investigate the prevalence of systemic and venous thromboembolism as well as major bleeding and mortality in relation to underlying risk factors and the impact of anticoagulation use in hospitalized patients with COVID-19.

Methods and results: Patients with COVID-19 admitted to Union Hospital, Wuhan, Hubei, China between January 08, 2020 and April 7, 2020 were enrolled in this retrospective study. Cox proportional hazard models were utilized to determine associated risk factors for clinical events, adjusting for the severity of COVID-19 infection, drug therapies, comorbidities, surgery, and use of antithrombotic drugs.

There were 1125 patients (49.9% male; mean age 58 years (standard deviation, SD, 15 years)) with a mean follow-up of 21 (SD 13) days. Approximately 25 (30%) patients with thromboembolism also suffered bleeding events.

Age was an independent risk factor for thromboembolism, bleeding events, and death (all p<0.05). After adjusting for the severity of COVID-19 infection, comorbidities, surgery, antiviral drugs, immunomodulators, Chinese herbs, and antithrombotic drugs, low lymphocyte counts (hazard ratio, HR, 95% confidence interval (CI), 1.03, 1.01-1.05, p=0.01) and surgery (HR 2.80, 1.08-7.29, p=0.03) independently predicted the risk for major bleeding, whereas liver dysfunction (HR 4.13, 1.30-13.1, p=0.02) was an independent risk factor for patients with both thromboembolism and bleeding events.

Conclusions: Patients with COVID-19 were at high risk for thromboembolic and bleeding events as well as mortality. The use of anticoagulants, especially parenteral anticoagulants, significantly reduced the risk for composite outcomes of thromboembolism, bleeding events, and death. The presence of AF was a contributor to systemic thromboembolism in COVID-19 patients.