Asthma prevalence in schoolchildren in a city in north-east Brazil

Asthma is a disease of increasing prevalence all over the world. The objectives of this study were to describe the prevalence of asthma and aspects of its morbidity in schoolchildren in Recife, and to evaluate the relationship between maternal schooling and asthma prevalence during 1994-1995. This is part of an international, multicentre research project, the International Study of Asthma and Allergies in Childhood (ISAAC). In a cross-sectional design, a probabilistic sample of 1410 children of 6 and 7 years of age and 3086 teenagers of 13 and 14 years were studied by questionnaire. The yearly prevalences of asthma symptoms in these two groups were 27.2% (CI 95%: 24.9-29.5%) and 18.1% (CI 95%: 16.4-19.8%), respectively; the cumulative prevalences of diagnosed asthma were 20.4% (CI 95%: 17.8-23.0%) and 19.7% (CI 95%: 19.4-22.2%), respectively, and the prevalences of asthma according to severity were: mild--68.9% and 81.3%, moderate--24.2% and 13.5%, severe--6.80% and 5.3%. During the previous year, the frequencies of crises with sleeping disorder were 23.2% and 13.0% and of disorder that limited speech 9.6% and 4.8%, respectively. There was a significant relationship between maternal education and cumulative prevalence of symptoms in both groups. It is concluded that asthma is a common disease which causes much morbidity in schoolchildren in Recife. The results suggest a relationship between low maternal education and a greater prevalence of asthma.