Epidemiological trends of allergic diseases in adolescents.

Objective: To assess the prevalences of asthma, allergic rhinitis, and allergic rhinoconjunctivitis in adolescents in the city of Belo Horizonte, Brazil, in 2012 by administering the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire, as well as to compare the observed prevalences with those found in studies performed 10 years earlier and employing the same methodology used here.

Methods: This was a cross-sectional study conducted between May and December of 2012 and involving adolescents in the 13- to 14-year age bracket. Participants were randomly selected from among adolescents studying at public schools in Belo Horizonte and completed the ISAAC questionnaire. Proportions were calculated in order to assess the prevalences of asthma, allergic rhinitis, and allergic rhinoconjunctivitis in the sample as a whole, and the chi-square goodness-of-fit test was used in order to compare the prevalences observed in 2012 with those found in 2002.

Results: The prevalences of symptoms of asthma, allergic rhinitis, and allergic rhinoconjunctivitis in 2012 were 19.8%, 35.3%, and 16.3%, respectively, being significantly higher than those found in 2002 (asthma, p = 0.006; allergic rhinitis, p < 0.01; and allergic rhinoconjunctivitis, p = 0.002).

Conclusions: The prevalences of asthma, allergic rhinitis, and allergic rhinoconjunctivitis among adolescents in 2012 were found to be high, having increased in comparison with those found 10 years earlier, despite efforts in prevention, diagnosis, and treatment.