A Comparison of Kawasaki Disease during the SARS-CoV-2 Pandemic with Multisystem Inflammatory Syndrome in Children

Objectives: This study aimed to compare the similarities and differences between the Kawasaki disease (KD) during the SARS-CoV-2 pandemic and multisystem inflammatory syndrome in children (MIS-C). Methods: The medical records of patients diagnosed with KD and MIS-C at a single center between July 2020 and November 2021 were retrospectively reviewed. Results: The study included 39 MIS-C patients (84.6% male) with a median age of 138 months and 17 KD patients (58.8% male) with a median age of 36 months. Compared with the KD patients, MIS-C patients were older (p<0.001), had longer hospital stays (p=0.023), elevated neutrophil count (p<0.001), C-reactive protein (p<0.001), procalcitonin (p<0.001), interleukin-6 (p<0.014), ferritin (p<0.001), fibrinogen (p<0.001), troponin I (p=0.001), NT-proBNP (p<0.001), and, D-dimer levels (p<0.001). They had more hypotension (p=0.024), decreased left ventricular function (p=0.023), and a greater need for corticosteroids (p<0.001), enoxaparin (p=0.045), and therapeutic plasma exchange (p<0.001). Patients with KD displayed a higher frequency of rash (p<0.001), oral mucosal changes (p<0.001), conjunctival injection (p<0.001), extremity changes (p<0.001), and cervical lymphadenopathy (p<0.001). They had a longer duration of fever (p<0.001), elevated white blood cell count (p<0.001), platelet count (p<0.001), and alanine aminotransferase level (p<0.001). The two groups were similar in terms of hemoglobin levels, erythrocyte sedimentation rate, albumin levels, or the frequency of coronary dilation/aneurysm, myocarditis, pericarditis, invasive mechanical ventilatory support, and intravenous immunoglobulin treatment. Conclusions: Older patient age, a greater presence of gastrointestinal and cardiac findings associated with hypotension, increased NT-proBNP levels, decreased left ventricular function, the use of various treatment modalities, and longer hospital stays suggest MIS-C, whereas a longer duration of fever and classical clinical features of KD favor KD.