Distinguishing Multisystem Inflammatory Syndrome in Children From COVID-19, Kawasaki Disease and Toxic Shock Syndrome

Background: Distinguishing multisystem inflammatory syndrome in children (MIS-C) from coronavirus disease 2019 (COVID-19), Kawasaki disease (KD), and toxic shock syndrome (TSS) can be challenging. Because clinical management of these conditions can vary, timely and accurate diagnosis is essential. Methods: Data were collected from patients <21 years of age hospitalized with MIS-C, COVID-19, KD, and TSS in 4 major health care institutions. Patient demographics and clinical and laboratory data were compared among the 4 conditions, and a diagnostic scoring tool was developed to assist in clinical diagnosis. Results: A total of 233 patients with MIS-C, 102 with COVID-19, 101 with KD, and 76 with TSS were included in the analysis. Patients with MIS-C had the highest prevalence of decreased cardiac function (38.6%), myocarditis (34.3%), pericardial effusion (38.2%), mitral regurgitation (31.8%) and pleural effusion (34.8%) compared with patients with the other conditions. Patients with MIS-C had increased peak levels of C-reactive protein and decreased platelets and lymphocyte nadir counts compared with patients with COVID-19 and KD and elevated levels of troponin, brain natriuretic peptide and pro-brain natriuretic peptide compared with COVID-19. Diagnostic scores utilizing clinical findings effectively distinguished MIS-C from COVID-19, KD, and TSS, with internal validation showing area under the curve ranging from 0.87 to 0.97. Conclusions: Compared with COVID-19, KD, and TSS, patients with MIS-C had significantly higher prevalence of cardiac complications, elevated markers of inflammation and cardiac damage, thrombocytopenia, and lymphopenia. Diagnostic scores can be a useful tool for distinguishing MIS-C from COVID-19, KD, and TSS.

Automated summary

This study compares the clinical characteristics and laboratory data of patients with MIS-C, COVID-19, KD, and TSS, and finds that patients with MIS-C have significantly higher prevalence of cardiac complications, elevated markers of inflammation and cardiac damage, thrombocytopenia, and lymphopenia compared with patients with the other conditions. Diagnostic scores utilizing clinical findings effectively distinguish MIS-C from COVID-19, KD, and TSS.