Prevalence of asthma and rhinitis in 13 year old adolescents in Porto, Portugal.
The prevalence of asthma and rhinitis has been increasing over the past few decades, but the last few years have seen these rates stabilise or even decrease. The aim of our study was to describe the prevalence of rhinitis, asthma or asthma-like symptoms in 13 year-old urban adolescents. Eligible participants were all students at state and private schools in Porto born in 1990. 2161 (77.5%) agreed to participate. Information was obtained using self-administered questionnaires inquiring into social, demographic, behavioural and clinical history including asthma and allergic diseases in the adolescent and the family. We used the Portuguese version of the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire and we also performed spirometry tests. In this sample of 13 year old urban adolescents the prevalence of asthma ever was 12.9%, 84.4% with physician diagnosis. Lifetime wheezing was reported by 18.3% and current wheezing by 9.3% of the adolescents. Rhinitis was referred to by 10.1%, but the prevalence of adolescents with sneezing ever, or a runny/blocked nose, was 32.0% and the prevalence in the last 12 months was 27.4%. We concluded that there was stabilisation or even decrease in the prevalence of asthma and rhinitis symptoms and diagnosis in adolescents reported in Porto, compared with the 2002 ISAAC study, as observed in other surveys in Europe. Asthma and rhinitis is frequently present in the same patient and nocturnal cough is an important symptom concomitant with nasal symptoms. Measures of lung function permitted the discrimination of adolescents with respiratory complaints.