Objectives: To calculate race-specific incidence rates of Kawasaki syndrome (KS) and to assess the association of KS with residential proximity to water in Washington State.
Design: Incidence study over 4 1/2 years, using cases identified with a new statewide hospital data set and a case-control study.
Setting: King, Pierce, and Snohomish counties in Washington State.
Patients: One hundred twelve population-based incident cases meeting Centers for Disease Control and Prevention criteria for KS.
Main outcome measures: Race-specific KS incidence rates and distance to permanent bodies of water among KS cases and matched controls.
Results: For the years 1985 through 1986 and 1987 through 1989, the annual KS incidence rates were 6.5 and 15.2 per 100,000 children younger than 5 years, respectively. Rates were highest among Asian Americans (33.3 per 100,000 children younger than 5 years in the 1987-1989 period), followed by blacks and whites (23.4 and 12.7 per 100,000 children younger than 5 years, respectively). The median distance to water did not differ between cases and controls and the proportion of cases living within 150 yd (135 m) of water was no greater than that of controls (odds ratio, 1.0; 95% confidence interval, 0.1 to 20.9).
Conclusions: With complete ascertainment of incident-hospitalized cases of KS, the race-specific rates are among the highest documented in the United States. The rate among Asian Americans was less than that found in Japan, perhaps due to differences in environmental exposures or variations in susceptibility among different Asian ethnic groups. Although we found no association with permanent bodies of water, future studies of KS should include home inspection to assess exposure to temporary collections of standing water.