Epidemiology of Kawasaki Disease in Canada 2004 to 2014: Comparison of Surveillance Using Administrative Data vs Periodic Medical Record Review

BACKGROUND: We have previously documented an increase in the incidence of Kawasaki disease (KD) in Ontario followed by a stabilization from 1995 to 2006. We sought to validate the estimation of incidence of KD using administrative data and to describe the epidemiology of KD across Canada from 2004 to 2014. METHODS: We queried the Canadian Hospital Discharge Database for hospital admissions associated with a discharge diagnosis of KD. The data set was manually curated and estimates of incidence were compared with those obtained from the retrospective triennial surveillances of KD performed in 2007 and 2010. RESULTS: The average number of cases per year identified through administrative data was 245 ± 45 vs 229 ± 33 from retrospective surveillance. This overestimation, representing 7 ± 6%, is similar to the historical percentage of patients originally diagnosed with KD in whom the diagnosis is subsequently excluded. The annual incidence of KD in Canada was 19.6, 6.4, and 1.3 cases per 100,000 children younger than 5 years, 5-9 years, and 10-14 years old, respectively, with important regional and seasonal differences. The incidence remained stable over the study period in the youngest age group but increased in both older age categories. Coronary artery aneurysms affected 3.5% of all patients, and 0.8% experienced associated major cardiac complications. CONCLUSIONS: Reliance on administrative data to determine incidence of KD is feasible and accurate with manual curation of the data. The incidence of KD in Canada seems to have plateaued for younger children. Differences in annual incidence observed between provinces remain to be explained, and might reflect genetic or environmental differences.