Kawasaki disease patients with six principal symptoms have a high risk of being a non-responder

Background: A diagnosis of Kawasaki disease (KD) is established using six principal symptoms. Because the principal symptoms are deeply connected with KD, it is thus important to investigate the usefulness of the principal symptoms for evaluating the disease severity of KD. Methods: Patients with definite KD or suspicion of KD were retrospectively examined. Blood test data and the incidence of patients who failed to respond to the initial i.v. immunoglobulin treatment (non‐responders) were compared between patients with six principal symptoms, including fever of ≤4 days, before treatment of KD (six‐symptom patients), and those with five or fewer symptoms (five‐symptom patients). Results: The study group of 207 patients who were treated with immunoglobulin consisted of 121 six‐symptom patients and 86 five‐symptom patients. The six‐symptom patients were older and had higher neutrophil proportion and total bilirubin, and lower serum sodium at diagnosis than the five‐symptom patients. Although the treatments did not differ between the groups, the six‐symptom patients had a higher incidence of non‐responders than the five‐symptom patients (17% vs 5%; P= 0.008). Logistic regression analysis showed that six‐symptom status was related to the risk of being a non‐responder (odds ratio [OR], 5.3; 95% confidence interval [95%CI]: 1.6–17.4). This association was still significant after adjustment for the effect of age, neutrophil proportion, and total bilirubin and sodium (OR, 4.4; 95%CI: 1.4–17.3). Conclusions: The number of principal symptoms before treatment is a useful guide to KD disease severity. Six‐symptom patients have a higher risk of being a non‐responder than five‐symptom patients.