Background: Asthma is one of the more prevalent diseases in childhood. Geographical differences have been found but it is unknown if they are true or are a consequence of the different methods used in the study of asthma.
Population and methods: In 9 Spanish populations: Almería, Barcelona, Bilbao, Bahía de Cádiz, Cartagena, Castellón, Pamplona, Valencia and Valladolid, 27,407 children aged 13-14 years were interviewed using the asthma written and video questionnaires of the ISAAC protocol. Comparisons among geographical areas were performed using a cluster analysis and a Poisson regression model adjusting by gender.
Results: The prevalence of resting wheezing using the video questionnaire was higher in males than in females (15.4% versus 12.6%) for wheezing ever. In the last year the prevalence of wheezing was 7.8% in males versus 7.0% in females. The analysis shows a group of centers with low prevalence of asthma symptoms: Valladolid, Almería, Castellón and Pamplona. Nevertheless there are also centers with higher prevalences as Bilbao, Barcelona and Bahía de Cádiz.
Conclusions: Prevalence of asthma and asthmatic symptoms is high in Spanish children aged 13-14 years. There are true geographical differences in Spain, being Valladolid, Almería, Castellón and Pamplona the areas with lowest prevalence.