Thrombotic events and prophylactic anticoagulation in pediatric patients with COVID-19: a systematic review and meta-analysis

Background: Venous thromboembolism (VTE) can occur in children with COVID-19, and the efficacy and safety of prophylactic anticoagulant therapy are uncertain. This study aimed to assess the incidence of VTE in pediatric patients with COVID-19, the association of D-dimer with thrombus formation, and the effectiveness and safety of prophylactic anticoagulation treatment.Methods: We systematically searched databases from January 2020 to February 2023. A systematic review and meta-analysis were conducted to determine the incidence of VTE in children and evaluate the efficacy and safety of prophylactic anticoagulant therapy.Results: Thirteen cohort studies and one clinical trial were included. The pooled incidence rate of VTE in affected children was 1.5% (95% CI 0.4-2.9%). Children with D-dimer levels five times higher than normal had a higher risk of VTE (OR 4.92, 95% CI 1.60-15.11). Prophylactic anticoagulant therapy did not significantly reduce the risk of VTE (OR 1.35, 95% CI 0.74-2.49). The safety of prophylactic anticoagulant therapy was relatively high, with major bleeding and all-cause mortality rates below 0.1% (95% CI 0.0-0.2%).Conclusions: The incidence of VTE in children with COVID-19 is low, and prophylaxis based on ISTH standards is reasonable. Low-molecular-weight heparin (LMWH) for VTE prevention has a high level of safety. However, more high-quality studies are needed to understand the impact of anticoagulant therapy on VTE incidence in pediatric patients with COVID-19.