ATOPY IN CHILDHOOD .2. RELATIONSHIP TO AIRWAY RESPONSIVENESS, HAY-FEVER AND ASTHMA

While airway hyperresponsiveness is usually associated with a diagnosi s of asthma or symptoms of wheezing, some individuals with rhinitis sh ow airway hyperresponsiveness as do some with no symptoms whatsoever. We have studied the correlations between symptoms, airway hyperrespons iveness and atopy as determined by skin-prick tests in a cohort of New Zealand children. A total of 662 members of a birth cohort were studi ed at age 13 years using a respiratory questionnaire, skin-prick tests to 11 common allergens, and an abbreviated validated methacholine cha llenge test to determine airway responsiveness. Airway hyperresponsive ness (methacholine PC20 FEV1 less-than-or-equal-to 8 mg/ml) was strong ly correlated with reported asthma and current wheezing (P<0.0001) and also with atopy, especially to house dust mite and cat (P<0.0001). As weal size for both house dust mite and cat increased, so did the prop ortion of children with airway hyperresponsiveness. All children with diagnosed asthma and airway hyperresponsiveness were atopic. Skin-test reactions to house dust mite and cat were strongly correlated with an y degree of measurable airway responsiveness (PC20 FEV1 less-than-or-e qual-to 25 mg/ml) in children with rhinitis (P < 0.0001), and remained significantly correlated even in children without current asthma, wit hout asthma ever and without rhinitis (P < 0.001). Atopy is a major de terminant of airway hyperresponsiveness in children, not only in those with reported histories of asthma and wheezing, but also in the absen ce of any history suggesting asthma and rhinitis.