During 1996 through 2006, 528 children < 18 years of age accounted for 582 hospitalizations with KS. The 1996–2006 average annual KS-associated incidence rate for children < 18 years of age was 16.3 patients per 100,000 children (). The average annual incidence rate for children < 5 years of age (50.4) was significantly higher than those for children 5–9 and 10–17 years of age (8.6 and 0.7, respectively; p < 0.001). The incidence for children < 1 year of age was significantly higher than that for children 1–4 years of age (77.4 and 43.6, respectively; p < 0.001). The median age of admission for children < 18 years of age hospitalized with KS was 2 years of age.
Characteristics of Children Hospitalized with Kawasaki Syndrome (KS) and KS Incidence Rates Among Children <18 and <5 Years of Age, Hawai‘i, 1996–2006.
Of the 528 children < 18 years of age, 441 (83.5%) were < 5 years of age and accounted for 487 hospitalizations. Forty-four patients < 5 years of age (10%) had more than one KS hospital stay, accounting for 9.4% of the hospitalizations. Approximately 1.1% of all KS patients < 5 years of age had a second hospitalization with KS as the primary diagnosis occurring ≥3 months after the first KS hospitalization during the study period.
The 1996–2006 average annual KS-associated incidence rate for children < 5 years of age was 50.4 patients per 100,000 children (). The annual incidence was relatively stable during the study period and ranged from 45.5 to 56.5. The average annual KS-associated hospitalization rate was 55.7 hospitalizations per 100,000 children.
For children < 5 years of age, the incidence for boys was higher than the incidence for girls (55.2 and 45.3, respectively; p=0.04; ). Among infants, the KS incidence rate was significantly higher for boys than that for girls (p = 0.001); there was no significant rate difference by sex among children in the 1–4 year old age group.
Asian and Pacific Islander children < 5 years of age accounted for 91.6% of the children < 5 years of age for whom race information was available; the KS incidence was 62.9 per 100,000. Among Asian and Pacific Islander children, the incidence was higher for infants than that for children 1–4 years of age. The Asian and Pacific Islander infant incidence was higher than that for white infants (104.6 and 4.8 per 100,000 children, respectively, p < 0.0001). Among all racial/ethnic groups < 5 years of age in Hawai‘i, Japanese children had the highest incidence (210.5), followed by Native Hawaiian children (86.9), other Asian children (84.9), and Chinese children (83.2; ). The KS incidence for Japanese children was more than twice that for Native Hawaiian children (p = 0.01) and much greater than that for white children (13.7; p < 0.0001).
Race/ethnicity of children hospitalized with Kawasaki syndrome (KS) and KS incidence rate estimates among children <18 and <5 years of age, Hawai‘i, 1996–2006.
The median age for children < 5 years of age was 21 months (25th and 75th percent quartiles of 10 and 36 months, respectively; ). The median age of admission for Japanese children < 5 years of age was 24 months, and was significantly higher than the median age of Native Hawaiian children (14.5 months; p = 0.03) and not statistically different from that for white children (26.5 months).
Proportion of Children <5 Years of Age Hospitalized with KS by Month of Age, Hawai‘i, 1996–2006.
No clear seasonal pattern in KS hospital admissions for children < 5 years of age was observed; admissions occurred throughout the study period with a small peak seen in December/January. The median length of hospital stay was 2 days (quartiles = 2 and 3.5 days). No in-hospital deaths were reported among children hospitalized with KS.