Clinical Impact of a Standardized Risk-Stratified Thromboprophylaxis Protocol for Multisystem Inflammatory Syndrome in Children.

OBJECTIVE: To evaluate the clinical impact of an institutional thromboprophylaxis protocol in patients with multisystem inflammatory syndrome in children (MIS-C), who are at increased risk for thromboembolism (TE). STUDY DESIGN: We conducted a single-center retrospective cohort study of children less than 18 years between March 2020 and December 2021. Eligible patients were confirmed with MIS-C and were managed with a standardized multidisciplinary treatment approach that included a thromboprophylaxis protocol to guide and unify clinical practice. For high-risk patients, prophylactic dose enoxaparin (target anti-Factor Xa 0.1-0.3 U/mL) was added. In high-risk patients with TE risk factors persistent at hospital discharge, thromboprophylaxis was prescribed for an additional 30 days. RESULTS: Of 135 patients with MIS-C, 124 (92%) required intensive care unit stay and 64 (47%) required a central venous catheter for a median duration of 5 days (IQR, 4-7). Prophylactic dose enoxaparin was initiated in 116 out of 121 patients (96%) deemed high-risk per our protocol at a median of 1 day after admission [IQR, 0-3] achieving target levels at a median of 1 day [IQR, 1-2]. The median initial anti-Factor Xa level was 0.13 u/mL [IQR, 0.05-0.19]. One patient (0.7%) developed symptomatic noncatheter related superficial vein thrombosis requiring therapeutic anticoagulation. Thromboprophylaxis was extended for 30 days after discharge in 108 out of 135 patients (80%). Bleeding events occurred in 5 patients during hospitalization (4.2%). All bleeding events were clinically relevant nonmajor bleeding. There were no deaths. CONCLUSIONS: Implementation of an institutional standardized thromboprophylaxis protocol in MIS-C was feasible and led to timely initiation of prophylactic anticoagulation and low rates of TEs and bleeding complications.