Prevalence of asthma in Melbourne schoolchildren: changes over 26 years.

OBJECTIVES: To determine the prevalence of asthma in the past 12 months in Melbourne schoolchildren aged 7, 12, and 15 years and to compare the prevalence of a history of asthma with that of 26 years ago. DESIGN: A questionnaire on respiratory symptoms was distributed to children for completion by parents and return to the school. Subjects were selected by a stratified cluster design. SETTING: Government and non-government schools in the greater Melbourne area, Australia. SUBJECTS: 10,981 children. Parents completed questionnaires for 3324 children aged 7, 2899 aged 12, and 2968 aged 15. The overall response rate was 90%. MAIN OUTCOME MEASURES: History of wheeze or asthma in the past 12 months and in lifetime. RESULTS: The prevalences of wheeze in the past 12 months were 23.1%, 21.7%, and 18.6% for 7, 12, and 15 year olds respectively. A history of wheeze was more common in boys than in girls at age 7 (443/1711 v 324/1614) and 12 (418/1767 v 322/1718) but not at age 15. Overall, 78% (1548) of those reporting wheeze also reported a history of asthma and 83% (1611) had used a bronchodilator. The prevalence of a history of asthma among 7 year olds was 46% compared with 19.1% in the 1964 survey, an increase of 141%. CONCLUSIONS: The current prevalence of asthma in Melbourne schoolchildren is high and has risen substantially over the past 26 years.