Objective: Before the use of the ISAAC (International Study of Asthma and Allergies in Childhood) questionnaire in epidemiologic surveys, little could be told about the comparative occurrence of asthma in the world due to differences in employed methods. In Brazil, the ISAAC questionnaire has been used in some urban regions. In this study it was applied in both, urban and rural areas, in order to estimate the prevalence of asthma among schoolchildren living in Montes Claros, Brazil.
Methods: A cross-sectional study was carried out using the ISAAC written questionnaire with four questions added on exposures of interest. The questionnaire was self-applied in 3,770 randomly selected schoolchildren aged 13 and 14 years.
Results: The prevalence of "wheezing in the last year" was 15.8%, and "asthma or bronchitis ever" was 23.8% with no statistically significant difference between boys and girls. There were significant differences between girls and boys regarding "wheezing ever" (37.8% and 33.6%), "sleeping disturbed by wheezing" (13.7% and 9.5%), and "nocturnal dry coughing without respiratory infection" (36.6% and 28.7%), respectively. "Wheezing in the last year" was found to be positively associated with "pet contact" (OR=1.27; 95% CI: 1.03-1.56), and "family history of asthma" (OR=1.79; 95% CI: 1.50-2.14), and negatively associated with "rural school" (OR=0.63; 95% CI: 0.44-0.91). But no association was found with sex, age, private/public school, and passive smoking.
Conclusions: The prevalence of asthma in Montes Claros was high and some symptoms were seen mainly among girls. The occurrence of "wheezing in the last year" showed to be associated with family history, contact with pets and urban schools.