Long-Term Effects of Allergen Sensitization and Exposure in Adult Asthma

Abstract

Background We investigated the effects of sensitization and exposure to common domestic allergens on longitudinal changes in lung function and bronchial hyperresponsiveness.Methods Subjects attended 2 visits that were 4 years apart. Skin prick testing was performed and household dust samples were collected for quantification of mite, dog, and cat allergens at baseline. Measurements of lung function, exhaled nitric oxide, and bronchial hyperresponsiveness were completed at both visits.Results Dust samples were collected in 165 of the 200 subjects completing both visits. Mean length of follow-up was 47 months. Bronchial hyperresponsiveness, measured at both visits in 86 subjects, deteriorated in those exposed to high mite allergen levels compared with those not exposed [mean (95% CI) doubling dose change PD20 = -0.44 (-1.07 to 0.19) vs 0.82 (0.27 to 1.36)], but improved in those exposed to high dog allergen levels compared with those not exposed [1.10 (0.33 to 1.86) vs 0.10 (-0.39 to 0.58)]. The associations were significant in the multivariate models. Cat allergen exposure was not associated with any changes in lung function, exhaled nitric oxide, or bronchial hyperresponsiveness.Conclusions In a 4-year prospective cohort of persons with asthma, exposure to high levels of dust mite allergens at baseline was associated with a subsequent increase in bronchial hyperresponsiveness. Keywords: asthma, allergens, environmental exposure, longitudinal studies