Prevalence of asthma-related symptoms and bronchial responsiveness to exercise in children aged 13-14 yrs in Barcelona, Spain.

It is not clear whether asymptomatic bronchial responsiveness is a risk factor for development of asthma. A cross-sectional study was conducted to determine the prevalence of asthma among schoolchildren from Barcelona (Spain). The association between respiratory symptoms and bronchial responsiveness to exercise was examined. For this study 3,033 schoolchildren aged 13-14 yrs were studied from the general population. Participants answered a respiratory questionnaire and a self-reporting video-questionnaire. A total of 2,842 children underwent bronchial responsiveness testing by exercise challenge. The study was part of the International Study of Asthma and Allergies in Childhood (ISAAC) project. The prevalence of "current asthma" (recent wheezing and bronchial responsiveness to exercise) was 4% and the prevalence of "wheezing only" 10%. A fall in peak expiratory flow rate (PEFR) > or = 15% after exercise testing was found in 324 (11%) children, 29 (9%) of whom presented clinical symptoms of asthma. Bronchial responsiveness to exercise was significantly associated with all items of the asthma questionnaire. The prevalence of asthma-related symptoms in this inner-city area was lower than frequently reported rates in other countries, although the prevalence of exercise-induced bronchoconstriction was relatively high, and threefold greater than in a geographical area in the vicinity of Barcelona. These findings are consistent with the current view that asthma-related symptoms and bronchial responsiveness to exercise have different meanings in a community survey, and that local environmental factors could influence the prevalence of bronchial responsiveness.