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Background: The etiology of Kawasaki disease (KD) is unknown. In Japan, the number of patients and incidence rate of KD has increased continuously since its discovery. The aim of this report was to analyze the latest nationwide epidemiological survey of KD in Japan., Methods: The 23rd nationwide survey of KD was conducted in 2015. To report on all patients diagnosed with KD in 2013 and 2014, a questionnaire was sent to hospitals with ≥100 beds containing pediatric departments, as well as specialized pediatric hospitals., Results: The number of KD patients reported was 15 696 in 2013 and 15 979 in 2014, resulting in an annual incidence rate of 302.5 and 308.0 per 100 000 population aged 0-4 years, respectively. The number of patients and incidence rate of KD in 2014 were the highest ever recorded in Japan. The number of patients diagnosed per month peaked in January, and a gradual increase in summer was also observed. Eight patients died of KD in 2013 and 2014., Conclusions: The number of patients and incidence rate of KD in Japan continue to increase. Continued surveillance of epidemiological trends of KD is therefore required., (© 2018 Japan Pediatric Society.)

Background: Although the incidence rates of Kawasaki disease (KD) in Japan have been determined in nationwide surveys, the cumulative incidence, that is, the proportion of those with a history of KD in the general population of 10-year-olds, is currently unknown. The aim of this study was therefore to assess the cumulative incidence of KD in Japan., Methods: Using the age- and sex-specific incidence rate of KD in Japan from the results of the nationwide surveys, incidence probabilities, that is, the age-specific number of KD patients divided by the population used in the vital statistics, and cumulative proportions of those not affected by KD up to the end of 9 years of age, were calculated. The cumulative incidence was then defined as 1 minus the cumulative proportion. The observed age classes were 0, 1, 2, 3, 4, and 5-9 years. All data were calculated by sex., Results: The cumulative incidence was 0.004833 for boys and 0.003474 for girls in 1991, but was 0.015284 and 0.012145 in 2014, respectively. According to these figures, 15.284 per 1,000 boys and 12.145 per 1,000 girls have been affected by KD by the age of 10 years. The birth-cohort cumulative incidences had similar trends., Conclusions: More than 10 persons in 1,000 have a history of KD at age 10 years in Japan., (© 2017 Japan Pediatric Society.)

Background: Although Kawasaki disease (KD) cardiac lesions can be treated with i.v. immunoglobulin (IVIG) and are associated with age and sex, the time course of cardiac lesions remains unclear on the large scale., Methods: We used the data of the 22nd nationwide survey of KD in Japan (2011-2012). We divided the time course of cardiac lesions into eight groups according to the combination of timing (first visit to hospital, acute phase, and sequelae) and presence of cardiac lesions (E, existence of cardiac lesions; N, non-existence of cardiac lesions): EEE, EEN, ENE, NEE, ENN, NEN, NNE, and NNN. For example, EEN shows that cardiac lesions existed at first visit to hospital and in the acute phase, but did not exist as sequelae. A total of 24 952 patients were analyzed., Results: The majority (90.6%) of patients belonged to the NNN group, followed by the EEN (3.21%) and NEN (3.33%) groups. Male sex and ages ≤5 months and ≥5 years tended to be more prevalent. Non-response to initial IVIG therapy was the most prevalent in all groups other than NNN., Conclusions: The time course of cardiac lesions and the relationship with sex, age, and IVIG therapy have been described. KD patients who are male, aged ≤5 months or ≥5 years, and non-responders to initial IVIG tend to have cardiac lesions at some point in the time course of KD., (© 2016 Japan Pediatric Society.)

Background: Since 1987, no study has reported the municipal-level geographical clustering of Kawasaki disease (KD) in Japan. Therefore, the aim of the present study was to identify the temporal and municipal-level geographical clustering of KD., Methods: The annual incidence rates of KD for each municipality were calculated using nationwide data from 73 758 patients with KD (2007-2012). To determine whether temporal and municipal-level clustering existed, we calculated the correlations of the annual incidence rates for each municipality during the study years, and compared these rates with those of the adjacent municipalities. Spatial scanning analysis was used to identify the geographical clusters for each year, and the incidence rates in those clusters were compared with the rates in the surrounding region., Results: The annual national incidence rate of KD, adjusted for the prefecture-specific response rate, was 322.45 patients per 100 000 children aged 0-4 years. The correlation between the annual incidence rates during 2 consecutive years was significantly positive (coefficients, 0.149-0.428). On spatial scanning analysis, the most likely clusters were in the Tokyo metropolitan area during 2007-2010 and 2012, and in Kumamoto prefecture during 2011., Conclusion: Kawasaki disease exhibits temporal and municipal-level clustering., (© 2016 Japan Pediatric Society.)