Distinguishing Multisystem Inflammatory Syndrome in Children From Kawasaki Disease and Benign Inflammatory Illnesses in the SARS-CoV-2 Pandemic.

Corwin, Daniel J; Sartori, Laura F; Chiotos, Kathleen; Odom John, Audrey R; Cohn, Keri; Bassiri, Hamid; Behrens, Edward M; Teachey, David T; Henrickson, Sarah E; Diorio, Caroline J; Zorc, Joseph J; Balamuth, Fran

OBJECTIVE The aim of the study was to compare presenting clinical and laboratory features among children meeting the surveillance definition for multisystem inflammatory syndrome in children (MIS-C) across a range of illness severities. METHODS This is a retrospective single-center study of patients younger than 21 years presenting between March 1 and May 15, 2020. Included patients met the Centers for Disease Control and Prevention criteria for MIS-C (inflammation, fever, involvement of 2 organ systems, lack of alternative diagnoses). We defined 3 subgroups by clinical outcomes: (1) critical illness requiring intensive care interventions; (2) patients meeting Kawasaki disease (KD) criteria but not requiring critical care; and (3) mild illness not meeting either criteria. A comparator cohort included patients with KD at our institution during the same time frame in 2019. RESULTS Thirty-three patients were included (5, critical; 8, 2020 KD; 20, mild). The median age for the critical group was 10.9 years (2.7 for 2020 KD; 6.0 for mild, P = 0.033). The critical group had lower median absolute lymphocyte count (850 vs 3005 vs 2940/uL, P = 0.005), platelets (150 vs 361 vs 252 k/uL, P = 0.005), and sodium (129 vs 136 vs 136 mmol/L, P = 0.002), and higher creatinine (0.7 vs 0.2 vs 0.3 mg/dL, P = 0.002). In the critical group, 60% required vasoactive medications, and 40% required mechanical ventilation. Clinical and laboratories features were similar between the 2020 and 2019 KD groups. CONCLUSIONS We describe 3 groups with inflammatory syndromes during the SARS-CoV-2 pandemic. The initial profile of lymphopenia, thrombocytopenia, hyponatremia, and abnormal creatinine may help distinguish critically ill MIS-C patients from classic/atypical KD or more benign acute inflammation.