Clinical Features of Kawasaki Disease in Children with an Atypical Age of Onset

To evaluate the frequency of patients younger than six months and older than five years in a large cohort of patients with Kawasaki disease (KD), and to determine the clinical characteristics and outcomes of patients with an age of onset outside the typical age distribution. We performed retrospective chart review of KD patients treated at our hospital during a six-year period. Data of patients were record from discharge database. Patients were divided into three groups according to age of onset of illness. The typical age group (6 months to 5 years) was used as a reference, and the clinical features of KD patients <= 6 months old and >5 years of age were analysed. A total of 2,318 cases were enrolled in this study population consisting of 1,432 boys and 886 girls. Cases <= 6 months of age and >5 years of age accounted for 14.7% (340) and 14.0% (325) of the overall sample. Compared with the typical age group, the younger age group had longer of hospital stay, higher proportion of incomplete KD (iKD) cases, fewer illness days at admission, and fewer number of major criteria. Compared with the typical age group, the older age group had longer illness days at admission, longer total fever duration, and higher rate of delayed diagnosis. There were no significant difference between two groups in term of the rates of iKD, intravenous immunoglobin resistance, and coronary artey lesion. Patients with KD <= 6 months of age tend to manifests incomplete symptoms with more pronounced systemic inflammation, while increased awareness contributed to improvement of diagnoses and outcomes. Patients with KD >5 years of age have relatively low levels of systemic inflammation without worse treatment and outcome, but were prone to delayed diagnoses.