Multisystem inflammatory syndrome in children associated with SARS-COV-2 and Kawasaki disease: experience of pediatric clinics in Russia

ABSTRACT

Introduction: COVID-19 in children is often asymptomatic or with only mild symptoms. However, since April 2020 there are many reports that the new coronavirus infection might be associated with pediatric hyperinflammatory condition, that fully or partially meets the criteria for Kawasaki disease (KD). This phenomenon was later called multisystem inflammatory syndrome in children (MIS-C) or pediatric inflammatory multisystem syndrome temporarily associated with SARS-CoV-2 (PIMS-TS). Objectives: Our study aimed to evaluate main clinical and laboratorial features and course of MIS-C and compare it with Kawasaki disease in children. Methods: The retrospective study included 50 children (34 male, 16 female), aged from 7 months to 16 years 9 months (median 8.8 years), who met the WHO criteria for MIS-C and 60 patients (34 male, 26 female, aged from 3 months to 6 years (median 2 years) with Kawasaki disease. Results: Prior COVID-19 infection in MIS-C group was confirmed by positive SARS-CoV2 test using RT-PCR (n=11) or IgM (n=21), IgG (n= 38) and/or close contact with a person with confirmed COVID-19 (n= 21) clinical features of previous COVID-19 infection were noted in 22 patients. Clinical sings of MIS-C included fever (100%), gastrointestinal disorders (81.6%), rash (90%), conjunctivitis (93.6%), sore throat (68.1%) cheilitis (54.6%), cervical lymphadenopathy (68.2%), hands and feet erythema/oedema (69.8%), hepathomegaly (64.6%). In the majority of patients elevated levels of inflammatory biomarkers, D-dimer, troponin, ferritin were found. Most of patients had a tendency to anemia (median hemoglobin 105 g/l). Platelet levels varied greatly (8-919∗109/l), 37.5% of patients had thrombocytopenia. Carditis and coronary artery dilatation were found in 48.9% and 22.7%, respectively. Arterial hypotension/shock was in 52.5%. Heart MRI showed signs of myocarditis (n=5) T1 prolongation (n=2);signs of myocardial edema, pericarditis, severe arrhythmia, and a tendency to diastolic overload (n=1), but no signs of ischemic or non-ischemic myocardial damage, and the global systolic function stayed normal. Patients were treated with high-dose glucocorticoids (93.6%), low-weighted heparin (100%), low dose of aspirin (64.4%), intravenous immunoglobulin (37.8%);Tocilizumab was used in three patients (6%). The median duration of hospitalization was 22 days, and 65.9% of patients required an ICU admission. Some of the most informative indicators for the differential diagnosis of MIS-C and KD are shown in the table. Conclusion: MIS-C is severe life-threatening condition in children, which pathogenesis and relation to COVID-19 requires further research. There are differences in the frequency of some signs that possibly can be used as a basis for differential diagnosis of the studied conditions.