Clinical indications for Kawasaki disease in febrile infants aged less than three months

The purpose of this study was to determine the clinical and laboratory indicators of KD in febrile infants aged less than three months. Febrile infants aged less than three months were enrolled and divided into three groups: KD, bacterial infection (BI), and non-bacterial infection (NBI). Laboratory data were analyzed at two time points: initially upon admission and at follow-up after 48-72 h of admission. A total of 491 patients (280 males and 211 females) were enrolled. According to the final diagnosis, 29 patients had KD, 120 had BI, and 342 had NBI. The infants in the KD group were older (p < 0.001), had prolonged pre-admission and total fever duration (p < 0.001), and had a lower rate of decreased activity (p < 0.05) compared to the infants in the BI and NBI groups. The KD group had a significantly higher level of initial c-reactive protein (CRP) compared to the BI and NBI groups, with a cutoff value of 4.85 mg/dL in comparison with the BI group and 3.32 mg/dL in comparison with the NBI group. Moreover, the KD group had a significantly higher follow-up platelet count compared to the BI and NBI groups, with a cutoff value of 533 × 10⁹/L in comparison with the BI group and 541 × 10⁹/L in comparison with the NBI group. When febrile infants aged less than three months have prolonged fever, less decreased activity, and a higher initial CRP level and follow-up platelet count, we must consider the possibility of KD.