ATOPY IN CHILDHOOD .1. GENDER AND ALLERGEN RELATED RISKS FOR DEVELOPMENT OF HAY-FEVER AND ASTHMA

Reasons for the gender differences in prevalence rates for asthma rema in unclear. We have examined the relationships between allergen skin-t est reactions and diagnoses of hay fever and asthma in New Zealand boy s and girls examined at the age of 13 years. Information on current an d past wheezing, diagnosed asthma, and hay fever was obtained for 662 subjects (341 boys) of a birth cohort followed longitudinally to the a ge of 13 years, using a physician-administered questionnaire. Atopic s tatus was determined by skin-prick tests to 11 common allergens. The p roportion of 13-year-old boys with current asthma was 1.6 times higher and of ever-diagnosed asthma 1.4 times higher than in girls, but the prevalence of recurrent wheeze (greater-than-or-equal-to three episode s per year) not diagnosed as asthma, or of hay fever, was not signific antly different between the sexes. The prevalence of diagnosed asthma increased with increasing numbers of positive skin tests, but hay feve r without asthma was little affected above one positive skin-test. Boy s had a greater prevalence of any positive skin-test (50.1 % vs 37.1%) , two or more positive tests (29.3% vs 21.8%), and responses to house dust mite (34.0% vs 23.1%) and cat (14.7% vs 11.2%). Gender difference s for asthma became insignificant when adjusted for skin-test responsi veness to house dust mite and/or cat. The proportion of children with diagnosed asthma increased with increasing size of weals to house dust mite and cat dan er. Gender differences in allergen sensitivities par tly explain the gender differences in diagnosed asthma in children. In both sexes, risk of asthma was primarily associated with sensitizatio n to indoor allergens (house dust mite and cat), and was related to th e magnitude of the skin-test response, while the risk of hay fever was primarily associated with grass pollen sensitivity.