J Karlberg, YL Lau

The main purpose of this study was to define the point prevalence and severity of asthma and allergies in 6-7 years old children in Hong Kong using the standardised questionnaire prepared by the International Study of Asthma and Allergies in Children (ISAAC). Another objective was to relate the wheezing prevalence in the past 12 months to potential risk factors.

A total of 3,618 (97.2%) of the questionnaires handed out in April and May 1995 were completed. 16.8% (18.9 boys, 14.5% girls) had wheezed at any time in the past and 9.2% (10.3% boys, 8.1% girls) in the past 12 months. 35.1% (38.8% boys, 31.3% girls) had symptoms of rhinitis in the past 12 months and 3 1.9% (35.8% boys, 27.9 girls) had allergic rhinitis at any time in the past. Only 4.2% had an itchy rash that was coming and going for at least 6 months in the past 12 months but 28.1% had eczema at any time in the past. Wheezing in the past 12 months was significantly associated with rhinitic symptoms (OR 6.79) and itchy rash (OR 3.51) in the past 12 months. Wheezing in the past 12 months also resulted in more severe rhinitic symptoms (OR 5.18) and more disturbed sleep due to the itchy rash (OR 4.52).

In a stepwise logistic multiple regression analysis we found four significant risk factors for wheezing; parental wheezing (one or both parents, OR 4.5), URTI (>4/year OR 3.0), Hong Kong born (OR 2.3) and male (OR 1.5). Factors not found to be significant (p>0.05) were history of parental asthma, rhinitis and eczema, school location and parental smoking. The prevalence of wheezing was 9.2% for the total population, but after stratifying for the most important risk factors we found prevalence figures ranging from 3.3% to 42.3%.

Asthma and other atopic allergies were common in Hong Kong children and they were highly related in both prevalence and severity. Boys were more affected than girls in both asthma and rhinitis, but not in eczema. Parental wheezing and respiratory tract infections in the child explain much of the prevalence variation in Hong Kong. Interestingly, but not as important is that being born in Hong Kong was a risk factor as well.