Severity of Acute Kawasaki Disease Can Be Predicted by Evaluating the Body Temperature at the Completion of an Initial Immunoglobulin Treatment

<b>Objective</b>: We aimed to determine whether the severity of acute Kawasaki disease (KD) can be predicted based on whether a patient remains febrile or becomes afebrile immediately after the completion of initial immunoglobulin treatment (IVIG). <b>Methods</b>: This retrospective cohort study at a single institution involved 306 patients with KD. They were categorized into four groups according to their fever status at two specific time points (end of the initial IVIG treatment and 24-36 h later): Group F-F, patients who remained febrile at both time points; Group F-AF, patients who were febrile at the end of the initial IVIG treatment but became afebrile 24-36 h later; Group AF-F, patients who were afebrile at the end of the initial IVIG treatment but became febrile 24-36 h later; and Group AF-AF, patients who remained afebrile at both time points. The clinical characteristics of the groups were compared. <b>Results</b>: Group F-F (n = 38) showed a significantly higher incidence of CAAs compared to Group AF-F (n = 37), 55.3% vs. 0.0% (<i>p</i> < 0.0001), although both groups were classified as resistant to the initial IVIG. <b>Conclusions</b>: In Japanese patients with acute KD, the presence or absence of fever at the completion of initial IVIG treatment may serve as an early predictor of the occurrence of CAAs. An earlier secondary treatment may be warranted for patients who are in a febrile state immediately after the completion of the initial IVIG treatment. Future research should include a prospective cohort study with a larger number of KD cases across multiple institutions to analyze the effects of other contributing factors related to CAL formation.