| Summary: | Background In the past half-century, the prevalence of asthma among children and adolescents has risen and asthma has become an important public health challenge in Sweden as well as in many other countries, necessitating further studies on this complex disease and its risk factor pattern. The studies included in this thesis aimed to investigate the clinical expression of childhood asthma over time, to describe the determinants of new-onset and remission of asthma, and to evaluate possible environmental risk factors in northern Sweden. Methods As the result of a repeated questionnaire survey among primary school children aged 7-8 years in three municipalities in the north of Sweden, two pediatric cohorts were formed, one in 1996 (n=3430) and one in 2006 (n=2585). The cohort created in 1996 was followed annually until the age of 19 years. Skin prick testing was performed on children in both cohorts. Lung function and bronchial hyperreactivity testing were carried out in children with asthma in the first cohort. The study participation and retention rates were very high in both cohorts. Among children in the second cohort living in Luleå, the home addresses were assigned to coordinates in a geographical information system (GIS) to evaluate the impact on respiratory health of living near roads with much traffic, which was measured as the number of vehicles daily. We used a validated reported diagnosis of asthma and International Study of Asthma and Allergies in Childhood (ISAAC) questions were incorporated into the questionnaire. A cross-sectional study of children of the same age ten years apart, longitudinal studies on asthma incidence and remission as well as a cross-sectional study on vehicle traffic were performed. Results While children aged 7-8 years in 2006 more often had a physician-diagnosed asthma compared to children of the same age in 1996 (7.4% vs 5.7%, p<0.001), they had less asthma symptoms, especially severe symptoms. In parallel, a more beneficial environment and a more intense treatment with ...
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