title: [Aims and methods of the ISAAC study (International Study of Asthma and Allergy in Childhood)].
abstract: The International Study of Asthma and Allergies in Childhood (ISAAC) is a multicentric, transversal, epidemiological study for investigating the epidemiology of asthma using a standardised methodology. In the case of Spain, centres in Almeria, Barcelona, Bilbao, Cadiz, Cartagena, Castellon, Valladolid and Valencia are collaborating in the study. The aim of the study is to obtain knowledge of the prevalence and seriousness of asthma amongst children living in different cities so as to compare the results between different Spanish cities and with other countries. This will make it possible to elaborate hypotheses on the aetiology of asthma. The ISAAC protocol studies two groups: children of 6 to 7 years of age, and adolescents of 13 to 14 years. The parents of the children of 6 to 7 years were sent questionnaires on asthma, atopic dermatitis, rhinitis and conjunctivitis, while the children in the 13 to 14 year old age group received the same written questionnaire together with a video questionnaire. A minimum of 3,000 children have been studied in each centre and age group. The information obtained from the ISAAC study, besides facilitating the study of the aetiology of asthma, will provide a baseline measure for studying the world evolution of the illness.