Prevalence and severity of asthma among school children in Hong Kong.

Introduction: This study presents contemporary epidemiological data regarding the prevalence and severity of asthma and wheezing among children in Hong Kong, which provides an update to the results of the International Study of Asthma and Allergies in Childhood (ISAAC) conducted in 1994-1995 and 2001-2003.

Methods: This cross-sectional investigation was based on the ISAAC study protocol. Responses from 1100 children aged 6 to 7 years (Primary 1-2) and 1048 children aged 13 to 14 years (Secondary 2-3) in Hong Kong between September 2020 and August 2021 were analysed. Sex differences within each age-group were assessed using Chi squared and independent t tests. Demographic information was entered into hierarchical logistic regression models to identify potential predictive factors associated with asthma severity. Annual change in prevalence was calculated via division of the prevalence by the number of years between surveys. Logistic regression modelling was conducted to identify risk factors associated with asthma severity.

Results: The prevalences of current wheezing were 6.19% and 4.97% in the primary and secondary school groups, respectively. The prevalences of asthma ever were 5.55% and 6.12%, whereas those of wheezing ever were 20.38% and 12.05%, in the primary and secondary school groups, respectively.

Conclusion: Asthma severity and prevalence have decreased in Hong Kong since 1994-1995. A followup study will explore the protective and risk factors contributing to these trends.