Study objectives: To investigate the relationship between current and early life factors and airway responsiveness to inhaled methacholine in children with a median age of 7.0 years.
Participants: Study subjects were a subset of a prospective birth cohort of children in the Boston area at high risk for atopy.
Methods: One hundred thirty-one children underwent both skin-prick testing to a panel of aeroallergens and a methacholine challenge test between 6.5 years and 8.8 years of age. Telephone questionnaires were performed at set intervals, and home dust samples were collected in the first year of life.
Results: Of the 131 participating children, 51% (67 patients) had at least one positive skin-prick test response and 28% (37 patients) had airway hyperresponsiveness (AHR) [provocative concentration of methacholine causing a 20% fall in FEV1 of < 4 mg/mL]. After adjusting for relevant covariates, AHR was strongly associated with sensitization to at least four aeroallergens (odds ratio [OR], 13.41; 95% confidence interval [CI], 3.03 to 59.42). In separate adjusted models, sensitization to cat (OR, 14.73; 95% CI, 3.64 to 59.55), dust mite (OR, 5.13; 95% CI, 1.94 to 13.56), cockroach (OR, 4.00; 95% CI, 1.19 to 13.50), and ragweed (OR, 10.08; 95% CI, 2.31 to 44.10) were significant predictors of AHR. However, no relationship was found with early life exposure to perennial aeroallergens or other perinatal and first-year-of-life factors.
Conclusions: Among young children at risk for atopy, sensitization to specific aeroallergens, but not early life exposures, is associated with increased airway responsiveness.