Search

Background: Kawasaki disease (KD) is a pediatric vasculitis, leading to coronary artery aneurysms (CAAs) in ~4–14%. Attention to the etiology and course of KD was generated by the close mimic of a SARS-CoV-2-induced phenotype, called multisystem inflammatory syndrome in children (MIS-C). Methods: A total of 1179 cases were collected from 2012 with ~50% of cases retrospectively included. Clinical characteristics were described and risk factors for CAA (persistence) were investigated. Phenotypic patterns of the prospectively included KD patients were evaluated. These patterns were also compared to the seronegative KD and seropositive MIS-C cases identified during the SARS-CoV-2 pandemic. Results: KD mostly affected boys and children < 5 years. IVIG resistance, CAAs, and giant CAAs occurred in 24.5%, 21.4%, and 6.6%, respectively. Giant CAAs were significantly more likely to normalize to a normal Z score in patients that were younger than 2.5 years old at the time of initial giant CAA (χ2 test p = 0.02). In our prospective (SARS-CoV-2-seronegative) KD series, there was a diminishing male predominance over time, whereas the proportions of incomplete presentations (p < 0.001) and patients with circulatory shock (p = 0.04) increased since the COVID-19 pandemic. Pre- and post-pandemic KD cases presented with different levels of C-reactive protein, thrombocyte counts, and hemoglobin levels over the years. Compared to pandemic KD, SARS-CoV-2-seropositive MIS-C patients were older (p < 0.001), and more often required intensive care admission (p < 0.001), with a gradual decrease over time between 2020 and 2022 (p = 0.04). KD carried a substantial risk of CAA development in contrast to MIS-C. Conclusion: the phenotypic changes seen over the last twelve years of our prospective follow-up study suggest a spectrum of hyperinflammatory states with potentially different triggering events within this clinical entity.