Cigarette smoking and allergic sensitization: A 32-year population-based cohort study

Background: Cigarette smoke has immunosuppressant effects, but its effect on allergic sensitization is unclear. Objective: To investigate associations between parental and personal smoking and skin prick tests (SPTs) for atopy in a population-based birth cohort of 1037 participants followed to adulthood. Methods: Parental history of atopic disease, parental smoking, and personal smoking were obtained at multiple assessments between birth and age 32 years. Atopy was assessed by SPTs for 11 common inhaled allergens at ages 13 and 32 years. Results: Children of atopic parents were less likely to have positive SPTs at age 13 years if either parent smoked (odds ratio, 0.55; P =.009). This association was not significant after adjusting for breast-feeding history, number of siblings, and childhood socioeconomic status. Subjects with atopic parents were also less likely to develop positive results to SPTs between ages 13 and 32 years if they smoked themselves (odds ratio, 0.18; P <.001). This reduction in risk remained significant after adjusting for multiple potential confounding factors. Neither parental nor personal smoking was significantly associated with allergic sensitization among subjects whose parents did not have a history of atopic disease. Few of those with positive SPT results at age 13 years had negative tests at age 32 years, and there was no evidence that this was influenced by smoking. Conclusion: Personal and parental smoking is associated with a reduced risk of allergic sensitization in people with a family history of atopy.