XXXX inhalation challenge studies in a selected pediatric population.

@entity1 @entity565 @entity566 @entity1729 @entity2710 @entity159
To determine bronchial reactivity patterns, 400 subjects, 5 to 21 yr of age, underwent a @entity2710 challenge in a Natural History of Asthma study. The diagnosis of @entity565 or @entity566 was based on a respiratory questionnaire. Subjects were nonsmokers and had had no @entity1729 for 1 month. Intradermal skin tests were done. The @entity2710 challenge response was expressed as the area beneath the dose-response curve (Area 35). Fifty-five asthmatics, 113 normal subjects from normal families, 103 normal subjects from @entity565 families, 60 normal twins, and 69 allergic subjects without @entity565 were studied. Overall, 52% of nonasthmatics and 47% of nonallergic subjects had an Area 35 less than 4,000 (800 breath units). There was a difference (p less than 0.05) in the distribution of @entity2710 Area 35 responses in normal subjects from that in normal families compared with normal subjects from @entity565 families. The age of the nonasthmatic subjects had an influence on the degree of bronchial reactivity. @entity2710 challenge studies in pediatric @entity1 must be interpreted with age, personal @entity159 , and family @entity565 history in mind.
