Does early exposure or sensitization to inhalant allergens predict asthma in wheezing infants? A 20-year follow-up.

Early sensitization to inhaled allergens predicts later asthma and allergy until school age, but studies on early exposure have given conflicting results. The purpose of this study was to evaluate the association between early wheezing, early exposure, or sensitization to pets and pollens and later asthma or allergy until adulthood. We have prospectively followed-up a cohort of 83 infants hospitalized for bronchiolitis in 1981-1982. Cat and dog ownership (early exposure) and inhalant allergen-specific IgE measurements (early sensitization) were registered at <3 years of age. Later, asthma and allergy were evaluated repeatedly between 3 and 20 years of age. Twenty-eight children were exposed to pets in early life, and 8 children were sensitized to pets and 10 children were sensitized to pollens. Birth season and early exposure or sensitization to pets were not significantly associated with later asthma and allergy. Wheezing was present at 3-6 years of age in 8 of 10 children sensitized to pollens (OR, 5.07; 95% CI, 1.48-17.31 versus nonsensitized), and asthma was present in 4 of 9 children at 8.5-10 years of age (OR, 9.53; 95% CI, 2.01-45.54). In multivariate analyses, early sensitization predicted asthma until 13.5-16 years of age. Seasonal rhinoconjunctivitis was not significantly associated with early exposure or sensitization to pets or pollens. In wheezing infants, early sensitization to seasonal pollens predicts subsequent wheezing and asthma until adolescence. No association was found between early exposure and sensitization to pets and later outcome.