ABSTRACT. Objectives. To determine the prevalence of Kawasaki disease in older children and to evaluate its clinical presentation, time to diagnosis, and outcome in comparison with younger patients with the disease.Methodology. A retrospective analysis of all patients discharged with a diagnosis of Kawasaki disease at a pediatric tertiary care hospital over a 12-year period.Results. A total of 133 patients were included in this study; 7.5% were 9 years of age or older at the time of illness. Patients were grouped by age: infants included children age 1 to 8 years of age and children 9 years of age or older. Older children had a higher frequency of abnormal cardiovascular physical examination (50%) versus children (6%) and infants (10%). The older age group and the infants had a higher prevalence of coronary artery abnormalities and poor left ventricular function than did the 1-to 8-year-olds. Eighty percent of the older children had coronary arteries that were either dilated or aneurysmal, and 30% demonstrated left ventricular dysfunction on initial echocardiography. The number of days to diagnosis after meeting the diagnostic criteria was 5.8 ؎ 2.3 for infants, 5.2 ؎ 1.5 for older children, and 1.9 ؎ 0.3 for children. Older children had a complicated course of Kawasaki disease compared with younger patients.Conclusion. We found a higher prevalence of older children with Kawasaki disease at our center than has previously been reported. Older patients, as well as infants, had a higher rate of coronary artery abnormalities than did the children between 1 and 8 years of age. Older age at the time of illness or a delay in treatment may be important factors in determining cardiac involvement in Kawasaki disease. Pediatrics 1998;102(1). URL: http:// www.pediatrics.org/cgi/content/full/102/1/e7; Kawasaki disease, coronary arteries, intravenous immunoglobulin.ABBREVIATIONS. KD, Kawasaki disease; CVS, cardiovascular; ECG, electrocardiography; LV, left ventricular; WBC, white blood cells; ESR, erythrocyte sedimentation rate; IVIG, intravenous immunoglobulin; ASA, acetylsalicylic acid. S ince its first description in the Japanese literature in 1967, 1 much has been written about Kawasaki disease (KD). A systemic vasculitis, KD is characterized by fever, mucocutaneous manifestations, and musculoskeletal changes, and its most devastating effects are on the heart, particularly the coronary arteries. The etiology of KD remains unknown, and its presentation can be diverse.2,3 The illness usually affects infants and children younger than 3 years.1 KD is extremely uncommon in patients 9 years of age and older. 4 -6 The most recent epidemiologic survey from Japan found that Ͻ1% of cases occurred in children 9 years of age and older. 6 Our experience suggested that KD affecting older children was more common than reported previously. Our clinical impression was that most of the older patients were diagnosed late in the course of their illness and, consequently, had more morbidity associated with the illness. Of interest to us were...