Current Prognostic Models Fail to Reliably Distinguish Kawasaki Disease From Pediatric Multisystem Inflammatory Syndrome Temporally Associated With COVID-9

Background: Along with the emergence of coronavirus disease 2019 (COVID-19), a hyperinflammatory multisystemic syndrome in children called PIMS appeared. Despite its close similarity to the Kawasaki disease (KD), the conclusion of PIMS being a distinct disease entity was reached quickly. Since then, research projects have been implemented to find differences and reliable distinction parameters with conflicting results. Therefore, the aim of this study was to explore existing prognostic models on their ability to distinguish the diagnoses. Methods: Two externally developed prognostic models were applied to 2 distinct datasets: one consisting solely of 26 KD and PIMS cases from Bayreuth, the other comprising 632 cases of both diagnoses reported by pediatricians from all over Germany and Innsbruck, Austria. The potential of the models to distinguish the diagnoses on a phenotypic level was evaluated based on their sensitivities and specificities, κ-coefficients by Cohen and correlation analysis. Results: The sensitivity and specificity of both prognostic models did not display a reliable distinguishability between KD and PIMS. Moreover, correlation analysis cannot confirm the correlation of most parameters utilized in the models with the PIMS diagnosis. The only parameter showing a positive correlation in both datasets was the patients’ older age. Conclusions: These findings are congruent with the general inconclusiveness in research concerning the distinction of KD and PIMS. We could not reproduce a distinguishability using the models or a correlation between the utilized parameters and PIMS except for one. Henceforth, research will need to focus on nonphenotypical properties for differentiation of KD and PIMS.