Spatiotemporal clustering of cases of Kawasaki disease and associated coronary artery aneurysms in Canada

Detailed epidemiologic examination of the distribution of Kawasaki disease (KD) cases could help elucidate the etiology and pathogenesis of this puzzling condition. Location of residence at KD admission was obtained for patients diagnosed in Canada (excluding Quebec) between March 2004 and March 2015. We identified 4,839 patients, 164 of whom (3.4%) developed a coronary artery aneurysm (CAA). A spatiotemporal clustering analysis was performed to determine whether non-random clusters emerged in the distributions of KD and CAA cases. A high-incidence KD cluster occurred in Toronto, ON, between October 2004 and May 2005 (116 cases; relative risk (RR) = 3.43; p < 0.001). A cluster of increased CAA frequency emerged in Mississauga, ON, between April 2004 and September 2005 (17% of KD cases; RR = 4.86). High-incidence clusters also arose in British Columbia (November 2010 to March 2011) and Alberta (January 2010 to November 2012) for KD and CAA, respectively. In an exploratory comparison between the primary KD cluster and reference groups of varying spatial and temporal origin, the main cluster demonstrated higher frequencies of conjunctivitis, oral mucosa changes and treatment with antibiotics, suggesting a possible coincident infectious process. Further spatiotemporal evaluation of KD cases might help understand the probable multifactorial etiology.