Policy Adherence to Antithrombotic Therapy for Prophylactic Anticoagulation in Multisystem Inflammatory Syndrome in Children (MIS-C) Associated with COVID-19.

Objective: The primary objective of this study was to characterize prescribing compliance with antithrombic therapy at a quaternary academic medical center per institutional multisystem inflammatory syndrome in children (MIS-C) guidelines. Study design: This single-center, retrospective study evaluated infants and children with MIS-C who received antithrombotic therapies for venous thromboembolism prophylaxis between May 2020 and January 2022. Results: Of the 62 patients admitted with MIS-C during the study period, 50 (81%) received enoxaparin prophylaxis and had at least one anti-Xa level drawn. 40 patients met our institutional guideline criteria for having an appropriately timed anti-Xa. The median weight-based dose of enoxaparin needed to attain a low molecular weight heparin anti-Xa between 0.2 to 0.5 IU/mL was 0.5 mg/kg (±0.09 mg/kg) every 12 hours. 39 (78%) patients achieved a goal low molecular weight heparin anti-Xa with the initial guideline dosage. Forty patients (80%) received concomitant aspirin at a median dose of 3.1 mg/kg/d (IQR 1.6-25 mg/kg/d). Conclusions: Overall, 40 (80%) patients were started on enoxaparin per our center's institutional guidelines. Our study demonstrated an empiric enoxaparin dose of 0.5 mg/kg (maximum initial dose 60 mg) every 12 hours resulted in zero venous thromboembolism events. In conjunction with a median dose of 3.1 mg/kg/d of aspirin, these doses resulted in one bleeding event.