3 - SIMILARITIES AND DIFFERENCES BETWEEN MULTISYSTEM INFLAMMATORY SYNDROME IN CHILDREN (MIS-C) AND KAWASAKI DISEASES SHOCK SYNDROME

Background: Few studies have addressed the relationship between multisystem inflammatory syndrome in children (MIS-C) and Kawasaki disease shock syndrome (KDSS), even though MIS-C and KDSS share organ dysfunction in addition to Kawasaki disease (KD)-like features. In this study, we investigated the characteristics of patients diagnosed with MIS-C or KDSS and compared the similarities and differences. We also estimated the incidence of KDSS and MIS-C in Korea, which had not previously been reported.

Methods: Medical records of patients diagnosed with MIS-C or KDSS at four hospitals in Korea from January 2013 to December 2022 were retrospectively reviewed.

Results: Thirty-one patients were enrolled in the study in either an MIS-C group (n = 22) or a KDSS group (n = 9). The incidence of KDSS in KD was 0.8% (9/1095) and the incidence of MIS-C versus KD was 10.2% (22/216). Compared with the MIS-C group, the KDSS group had longer hospital stays and more severe systemic inflammation (e.g., anemia, elevated C-reactive protein, hypoalbuminemia, and pyuria) and organ dysfunction (e.g., number of involved organs, shock, vasoactive infusion, and intensive care unit admission). All patients in the MIS-C group, but none in the KDSS group had laboratory evidence of SARS-CoV-2 infection. Comparisons of other variables of demographic, clinical, and laboratory characteristics revealed no statistical differences.

Conclusion: All patients diagnosed with MIS-C or KDSS in this study exhibited KD-like features, systemic inflammation, and organ dysfunction. The overall severity of systemic inflammation and organ dysfunction was higher in KDSS patients than in those with MIS-C. The most important difference between MIS-C and KDSS was whether SARS-CoV-2 has been identified as an infectious trigger.

(Figure) Relationships between KD, KDSS, and MIS-C. (A) KD is characterized by KD-like features and systemic inflammation. Infectious triggers are expected to play an important role in the pathogenesis of KD. (B) KDSS is diagnosed when shock presenting as organ dysfunction is observed in patients with KD-like features and systemic inflammation. (C) MIS-C is diagnosed when SARS-CoV-2 is identified in patients with KD-like features, systemic inflammation, and organ dysfunction such as shock.