Lina Mazine, BSc
Medical Student
Sainte Justine, Canada
BACKGROUND
KD has been reported in many countries with different incidence rates depending on regions and populations, the highest being found in Eastern-Asia, particularly in Japan. Hence, children of Asian descent are more susceptible to developing the disease. However, in Quebec Province (Canada), clinical observations have led to believe that other ethnicities may present a similar or even higher risk.
AIM
We sought to provide an epidemiological profile of KD patients in Quebec, and compare it with global epidemiological data.
METHODS
Registries from the 5 collaborating hospitals across the province (covering the vast majority of the pediatric population) were queried for patients diagnosed with KD between 2001 and 2017. We used a standardized questionnaire filled with a parent or the recruited patient (if adult) to collect epidemiological data. The country of origin of the patients' four grandparents were distributed based on Statistics Canada ethnic categories. Annualized incidence rate (AIR) was calculated using the standard denominator (SD) of 100,000 iso-ethnic children under 5 years old. Multi-ethnic counts were calculated according to Statistics Canada methodology. Eight ethno-regional conglomerate classes were used (Canadian Institute for Health Information); accordingly, French-Canadians, a genetically established Founding Father, were considered separately.
RESULTS
From a total of 439 eligible cases, 326 (74,3%) consented were included. Among the included patients, 42% were of mono-ethnic origin, while 58% were of multi-ethnic origin. Caucasians presented a lower incidence rate (3.5/SD) than East and Southeast Asians (17.1/SD). However, the annualized incidence rate was found to be highest amongst French-Canadians with a rate of 72.5/SD, compared to 37.5/SD for Japanese origins. Additionally, an important representation of KD patients was observed amongst Middle Eastern (11.9/SD), Latin (11.4/SD) and Black African (9.5/SD) ethnicities. Finally, there were no major differences in ethnic categories when multi-ethnic versus mono-ethnic cases were compared.
CONCLUSION
In this unique investigation of patient ethnic origins, we found an overrepresentation of the French-Canadian ethnicity in the annualized incidence rate of KD in the province of Quebec. Children of Arab, Latin and African descent also exhibited a high incidence rate. These findings shed light on possible ethnic predispositions in a North-American populational environment. Although the overrepresentation of French-Canadians in the exposed population represents a possible bias, potential unique factors contributing to KD in Quebec is worth further exploration.