Background and ObjectivesDiagnosis of Kawasaki disease (KD) is based on 5 clinical features. Incomplete KD (IKD), which has fewer features, is more common in infants and older children, in whom the rate of coronary artery aneurysms is paradoxically higher. We conducted this study to evaluate risk factors associated with age-at-diagnosis on coronary arterial lesions (CAL) in patients with IKD.Subjects and MethodsRetrospective data from 396 patients with KD in a single center were collected from January 2003 to July 2007. Patients were grouped according to their age at diagnosis; Group A (<1 year of age), Group B (1≤age<5 years of age), and Group C (≥5 years of age).ResultsAmong a total of 396 patients with KD, 87 (22.0%) were in Group A, 246 (62.1%) in Group B, and 63 (15.9%) in Group C. In groups A and C, lag times for starting intravenous immunoglobulin (IVIG) were longer than in Group B. There were no differences in the incidence of IKD, late CAL, or rates of IVIG retreatment among the three groups. Among 174 patients with IKD, there were no age-related differences in late CAL incidence or IVIG retreatment. Compared with typical KD, duration of fever and lag times to start IVIG were longer, and the rate of IVIG retreatment was higher in IKD, but there was no difference in the risk of CAL between typical KD and IKD.ConclusionIn the management of KD, especially the incomplete type, age-associated factors appear not to be significant for predicting the development of CAL.