Hospitalizations for Kawasaki syndrome among children in the United States, 1997-2007

Background: The present study describes the rate and trends of childhood hospitalizations with Kawasaki syndrome (KS) in the United States. Methods: Retrospective analysis of hospitalizations with KS among children <18 years of age in the United States using the Kids' Inpatient Database (1997, 2000, 2003, and 2006) and the Nationwide Inpatient Sample (1998-2007). Results: The KS-associated hospitalization rate for children <5 years of age was 20.8 (95% CI: 18.5-23.1) per 100,000 children in 2006. Annual rates remained constant during the study period, except for a peak in 2005. In 2006, 76.8% (SE = 0.9%) of an estimated 5523 (SE = 289) KS-associated hospitalizations among children <18 years of age were <5 years of age. The mean age for all children at hospitalization was 3.0 years (SE <0.1); 25.7 months (SE = 0.3) for children <5 years of age, and 24.8 months (SE = 0.4) and 27.1 months (SE = 0.5) for boys and girls, respectively. The rate for boys was higher than that for girls (24.2 [95% CI: 21.3-27.1] and 16.8 [95% CI: 14.7-18.9], respectively). The rate for Asian/Pacific Islander children (30.3 [95% CI: 20.2-40.4]) was the highest among the racial groups. Conclusions: The national KS-associated annual hospitalization rate for children <5 years of age from 1997 to 2007 was relatively stable and was similar to previously published rates, except for an increase in 2005. Most hospitalizations were in children <3 years of age with few hospitalizations during the first 2 months of age. Children of Asian/Pacific Islander descent had the highest hospitalization rate.