ATOPY IN CHILDHOOD .3. RELATIONSHIP WITH PULMONARY-FUNCTION AND AIRWAY RESPONSIVENESS

The relationship between atopy and pulmonary function in children, and how these relate directly or indirectly to airway hyperresponsiveness , is uncertain. We have examined these relationships in a sample of 13 -year-old children. A questionnaire on respiratory symptoms, skin-pric k tests to 11 common allergens, spirometry and an abbreviated methacho line challenge test were completed by 662 members (341 boys) of a birt h cohort of New Zealand children followed longitudinally to age 13. Th ere was a significant relationship between the presence and degree of atopy, and baseline pulmonary function. Low FEV1/VC ratios were associ ated with a greater likelihood of airway responsiveness, not only in s ubjects with diagnosed asthma, but also in the full cohort and in the sub-group of 426 children who denied asthma or current wheeze. The rel ationships between baseline FEV1/VC and airway responsiveness were str onger in atopic than in non-atopic children, with the strongest relati onships in children sensitive to house dust mite and/or cat dander. In the presence of atopy, progressively lower levels of lung function we re strongly associated with a higher prevalence of airway responsivene ss (P<0.001). In non-atopic subjects, only those with the most impaire d lung function (FEV1/VC <75%) showed any substantive prevalence of ai rway responsiveness. The relationship between the degree of atopy and the FEV1/VC ratio, although significant in univariate analysis, became completely non-significant after accounting for airway responsiveness . In 13-year-old children, atopy, especially to house dust mite and ca t dander, was correlated with pulmonary function expressed as FEV1/VC ratio. Airway responsiveness likewise correlated with impaired baselin e lung function. The apparent relationship of lung function to atopy o ccurred primarily as a result of the relationship between atopy and ai rway responsiveness. Atopy and impaired lung function were additive fa ctors predicting airway responsiveness.