[Allergy and bronchial reactivity in children and adolescents from Copenhagen].
The relationship between bronchial responsiveness and the results of a skin prick test was studied in 527 children and adolescents from Copenhagen. All participants completed a questionnaire concerning birth weight, breastfeeding, month of birth, month of examination, allergic symptoms in themselves or their parents. Furthermore, skin prick test reactivity to nine common aero-allergens, lung function, serum IgE, and bronchial responsiveness to histamine and exercise were measured. A total of 158 (30%) subjects showed signs of allergy (defined as a positive reaction to the skin prick test), of whom 53 (10%) subjects had positive skin reactivity and 105 subjects had moderate skin reactivity; 366 (70%) subjects had no signs of allergic disease as measured by the pride test. The most important marker for the degree of bronchial responsiveness was asthma (p < 0.001), month of examination (p < 0.01) and allergy (skin reactivity to one or more allergens) (p < 0.05). Furthermore, the degree of bronchial responsiveness to inhaled histamine was significantly related to a history of asthma in two first degree relatives (p < 0.01) and the skin reactivity to house-dust mites (p < 0.01), whereas the degree of bronchial responsiveness to exercise was significantly associated with the level of serum IgE (p < 0.05), month of birth (p < 0.001) and birth weight (p < 0.05). In conclusion, allergy is an important risk factor for the presence of increased degree of bronchial responsiveness to inhaled histamine and to exercise.