Prevalence of asthma and wheeze in Hong Kong schoolchildren: an international comparative study.

Comparison of asthma prevalence between populations is difficult because of lack of uniformity of methodology and agreement on the definition. This study aims to determine and compare the prevalence of wheeze and respiratory symptoms in Hong Kong schoolchildren with that in Melbourne children by using identical questionnaires. Schools were randomly selected in different regions of Hong Kong and three age groups (7, 12 and 15 yrs) were chosen for the study. The Chinese version of the questionnaire used in a recent Melbourne survey was distributed to children for completion by their parents. A total of 1,800 questionnaires was issued and 1,689 returned (response rate = 94%). The prevalence of wheeze in the past 12 months was 7 (5.1-8.0), 5 (3.0-6.7) and 4 (1.7-5.6) % for 7, 12 and 15 year olds, respectively. The prevalence of a history of asthma in the respective age groups was 10 (7.1-12.9), 8 (7.5-9.2) and 7 (5.0-9.6) %, respectively. Whilst a history of wheeze ever was more common in boys than in girls and 12 yr olds (14% vs 5%), wheeze in the past 12 months was more common in boys than in girls aged 7 yrs (9 vs 4%). We conclude that the prevalence of wheeze and asthma in school children was low in Hong Kong compared to Melbourne. Environmental differences between the two regions may be important in the pathogenesis.