Smoking and the development of allergic sensitization to aeroallergens in adults: a prospective population-based study. The Copenhagen Allergy Study

Background: Several cross-sectional population-based studies have reported a negative association between smoking and allergic sensitization to aeroal lergens. In a prospective study, we investigated the association between sm oking and the development (incidence) of allergic sensitization as reflecte d by skin prick test (SPT) positivity and specific IgE positivity. Methods: Participants in a population-based study of 15-69-year-olds in 199 0 were invited to a follow-up in 1998. Thus, SPT positivity and specific Ig E positivity to common aeroallergens were assessed in 734 subjects (partici pation rate: 69.0%) on two occasions 8 years apart. The effect of smoking o n the development of allergic sensitization was adjusted for potential conf ounders such as age, sex, family history of hay fever, educational level, a nd total IgE. Results: During the follow-up period, 58 and 33 subjects developed SPT posi tivity and specific IgE positivity, respectively. The risk of developing SP T positivity (adjusted odds ratio: 0.45, 95% CI 0.21-0.98) and specific IgE positivity (adjusted odds ratio: 0.62, 95% CI 0.26-1.49) was lower among s ustained smokers than never-smokers. Conclusions: In this adult population, sustained smoking was negatively ass ociated with the development of allergic sensitization to aeroallergens dur ing an 8-year follow-up. This negative association, if real, might be due t o an immunosuppressive effect of smoking.