Declining asthma prevalence in Hong Kong Chinese schoolchildren

Abstract
Summary: Background Many studies have reported an increase in the prevalence of asthma and related atopic disorders. The lack of standardized methodologies and ‘objective’ measurements make reliable comparison and monitoring of trends of asthma very difficult.Methods In this study, a total of 3321 schoolchildren aged 13–14 years were recruited for study using the Phase III Protocol of the International Study of Asthma and Allergic discase in Childhood (ISAAC). The results were compared with those obtained in the Phase I ISAAC study (1994–95), which used the identical and validated core questionnaires.Results The prevalence rates of physicians' diagnosis of asthma were similar in the two surveys (11.2% and 10.2%), but the prevalence rates of wheeze (written questionnaire) in the past year have decreased from 12.4% in 1994–95 to 8.7% in 2002 (PPP=0.013).Conclusion Using the same standardized and validated ISAAC questionnaire, the prevalence rates of asthma symptoms in Hong Kong Chinese schoolchildren have decreased since 1994. The exact reasons for such trend remain to be explored.