175 - EFFECT OF THE COVID-19 PANDEMIC ON THE EPIDEMIOLOGY OF KAWASAKI DISEASE IN CANADA

Background: The epidemiology of KD in Canada has been systematically documented using historical data (1979-1995), triennial surveillances (1995-2009) and administrative data (2010-present). Prevalence increased from 1979-2004, incidence and epidemiological profile has been stable between from 2004-2018. We sought to determine the effect of the COVID-19 pandemic on the prevalence and epidemiology of KD in Canada.

Methods: We compared the admission rate and patient characteristics of children hospitalized for KD at the Hospital for Sick Children in Toronto before (2016-Feb 2020), during (Mar 2020-Jul 2022) and after (Aug 2022-Jun 2023) the COVID pandemic. We excluded from the analysis children from early in the pandemic who in retrospect were likely to have MIS-C but were originally diagnosed as having KD. The Hospital for Sick Children is considered representative of the rest of Canada, it is the largest pediatric hospital and sees ~40% of all patients with acute KD in Canada. This analysis is being done in anticipation of the pan-Canadian data being released by the Canadian Institute of Health Information to be released mid-2024, at which time the analysis will be repeated.

Results: The average rate of admission went from 8.5±3.5 patients/month before the pandemic to 5.3±3.7 during the pandemic (-38% relative risk reduction, p< 0.001 vs. previous) and partially rebounded to 7.4±2.9/month after the pandemic (p=0.30 vs. previous, p=0.07 vs. during). The seasonality of KD in Canada is well document with annual peaks in January to March and troughs in August and September. Winter peaks were present between 2016 and 2020 (with an exception in 2019) and summer lows were seen every year between 2016 and 2019. Seasonal peaks were preserved in 2020 and 2021 but were suppressed in 2022. The expected winter 2023 seasonal peak was observed. Patients diagnosed early in the pandemic were more likely to present with incomplete KD (59% during vs. 31% pre and 30% post, p< 0.001). Patients from during and after the pandemic were more likely to present with respiratory (46% during vs. 76% after vs. 22% pre, p< 0.001) or abdominal symptoms (59% during vs. 64% after vs. 29% pre, p< 0.001). There were no differences in age at admission, sex distribution, total duration of fever, admission to the ICU or maximum coronary artery z-score.

Conclusion: The COVID-19 pandemic significantly changed the epidemiology of KD in Canada and regular epidemiological patterns have not yet recovered; patients’ outcomes have remained stable throughout the pandemic.