Predicting recalcitrant hyperinflammatory disease course in children with Kawasaki disease and MIS-C

Hyperinflammation ranges from monophasic to rapidly progressive, life-threatening courses. Early biomarkers to identify high-risk children are needed. This single-center cohort included consecutive children with hyperinflammation between 01/2021 and 01/2024. Demographic, clinical, laboratory, cardiac imaging, and treatment data were analysed. Of 80 patients, 56 (70%) had a recalcitrant course. Fever was universal. Rash, mucosal involvement, and conjunctivitis were more common in the monophasic group, while abdominal pain, neurological signs, pleural effusion, lymphopenia, thrombocytopenia, hypoalbuminemia, and elevated ferritin characterised the recalcitrant group (p < 0.01). Myocarditis and reduced ejection fraction occurred only in the recalcitrant cohort; coronary artery changes were more frequent in monophasic cases (21% vs. 5%). All survived. All received IVIG; steroids and anakinra were used only in recalcitrant cases, who also had longer hospital stays, ICU admissions (21% vs. 0%, p < 0.01), and required inotropes/ventilation. Baseline SAA, IL-2R, and NT-proBNP were significantly higher in the recalcitrant cohort. In ROC analyses, NT-proBNP showed the highest diagnostic accuracy (AUC 0.912), followed by IL-2R (AUC 0.873) and SAA (AUC 0.793) (all p < 0.001). NT-proBNP, IL-2R, and SAA were strongly associated with a recalcitrant hyperinflammatory course and may aid early prognostication and monitoring.