The aim of this study was to investigate the epidemiologic status of Kawasaki disease (KD) in infants ≤6 months of age.

For the epidemiologic study of KD in Korea, data from 22,674 KD patients were collected from 1997 to 2005 on a 3 -year basis by a retrospective survey. From this survey, data of 1,739 KD patients ≤6 months of age were analyzed and compared with those of KD patients >6 months of age.

A total of 1,739 patients ≤6 months of age, including 1,088 males and 651 females, represented 7.7% of total KD patients. These subjects included 22 patients aged <1 month, 171 patients aged 1-2 months, 304 patients aged 2-3 months, 407 patients aged 3-4 months, 372 patients aged 4-5 months, and 463 patients aged 5-6 months. Their mean age of onset was 4.3 months, and the male-to-female ratio was 1.67 :1 . Incidences of coronary arterial (CA) abnormalities (21.0% versus 18.7%) and CA aneurysms (4.7% versus 3.1%) detected by echocardiography showed differences between patients with KD younger and older than 6 months, respectively.

Comparison of data from KD patients >6 months old with data from 1,739 KD patients ≤6 months old showed significantly higher incidences of CA abnormalities and CA aneurysms in the younger patients.