Allergic sensitisation and asthma in Swedish adults

Abstract

The prevalence of asthma has increased in many countries. Heredity, atopic sensitisation, smoking and other environmental factors are suspected risk factors. The aims of this thesis were to investigate the occurrence and predictors of sensitisation, asthma and allergic rhinitis (AR), the relationship between sensitisation and asthma and the importance of allergen exposure in asthmatic adults sensitised to pets. Random population samples of almost 10,000 adults aged 20-44 years from Göteborg, Uppsala and Västerbotten were investigated with a postal questionnaire. Random subsamples of about 500 subjects from each area were investigated using questionnaire, skin tests, specific and total IgE and test for bronchial hyper-responsiveness (BHR). The postal questionnaire was repeated after 3 years. In another study, 129 asthmatics sensitised to pets were investigated using similar methods. Cat or dog owners were compared with subjects without pets. The prevalence of atopy was 35%. Low age, male sex and atopic heredity were predictors of sensitisation. Pollens and pets were the most frequent sensitising allergens. Sensitisation to Parietaria occurred in 3.4% of the population in Göteborg and was associated with AR. Residents born in the Nordic countries were more frequently sensitised to pets and more rarely to mites compared with subjects born in other countries. The prevalence of asthma and AR was 6% and 17% respectively. Low age, AR and sensitisation were associated with asthma and onset of asthma. Smoking was associated with onset of asthma, particularly among non-atopics. Pets were the sensitising allergens most closely associated with asthma, BHR and onset of asthma. Sensitisation to pollens and pets was associated with AR. Pets at home appeared to worsen asthma, airway inflammation and BHR in pet-sensitised asthmatics. The difference in severity between asthmatics with or without pets was substantial and indicates that removal of a pet from home could grant a considerable reduction of medication. Pet owners reported pet-elicited symptoms less frequently than non-pet owners, while more pet owners reported symptoms from dust at home.