The flowchart of our prospective study. A total of 800 patients were diagnosed as KD on admission. Those who had received IVIG treatment at other medical facilities without serum PCT value (n = 185) or did not receive IVIG treatment within 10 days from fever onset (n = 36) were firstly excluded. Another 28 patients were excluded due to lack of PCT data before IVIG infusion. Additionally, we excluded 21 patients because of incomplete other laboratory data (n = 11) or lack of follow-up results (n = 10). Finally, the data of 530 patients were analyzed, including 76 initial IVIG-resistant patients and 454 IVIG-responsive patients. Initial IVIG-resistant group were then divided into repeated responsive subgroup (n = 41) and repeated resistant subgroup (n = 35). Then data analysis and multivariate logistic regression analysis were performed in these groups.