Venous and Arterial Thrombosis in Ambulatory and Discharged COVID-19 Patients: A Systematic Review and Meta-analysis.

Introduction  Venous and arterial thromboses are frequently observed complications in patients with severe novel coronavirus disease 2019 (COVID-19) infection who require hospital admission. In this study, we evaluate the epidemiology of venous and arterial thrombosis events in ambulatory and postdischarge patients with COVID-19 infection. Materials and Method  EMBASE and MEDLINE were searched up to July 21, 2021, in addition to other sources. We included studies that assessed the epidemiology of venous and arterial thrombosis events in ambulatory and postdischarge COVID-19 patients. Results  A total of 16 studies (102,779 patients) were identified. The overall proportion of venous thromboembolic events in all patients, that is, ambulatory and postdischarge, was 0.80% (95% confidence interval [CI]: 0.44-1.28), 0.28% (95% CI: 0.07-0.64), and 1.16% (95% CI: 0.69-1.74), respectively. Arterial events occurred in 0.75% (95% CI: 0.27-1.47) of all patients, 1.45% (95% CI: 1.10-1.86) of postdischarge patients, and 0.23% (95% CI: 0.019-0.66) of ambulatory patients. The pooled incidence rate estimates per 1,000 patient-days for VTE events were 0.06 (95% CI: 0.03-0.08) and 0.12 (95% CI: 0.07-0.19) for outpatients and postdischarge, respectively, whereas for arterial events were 0.10 (95% CI: 0-0.30) and 0.26 (95% CI: 0.16-0.37). Conclusion  This study found a low risk of venous and arterial thrombi in ambulatory and postdischarge COVID-19 patients, with a higher risk in postdischarge patients compared with ambulatory patients. This suggests that regular universal thromboprophylaxis in these patient populations is probably not necessary.