Which patterns of allergen sensitization identify an increased risk for asthma in children with early-onset atopic dermatitis?

Background: Atopic dermatitis (AD) is a chronic inflammatory skin disorder affecting mostly young children. Over the last decades, it has been strengthened the so-called ‘atopic march’ theory, defined as the natural progression from AD towards the development of respiratory allergy. Although longitudinal studies aimed to identify the possible risk factors for asthma, several aspects of this phenomenon still need to be clarified. The aim of this study is to evaluate the natural course of inhalant and food allergen sensitization in children with AD and its relation to asthma. Method: We enrolled 99 children with IgE-mediated AD referred to the Pediatric Dermatology and Pediatric Allergology Units of Bologna University. All children performed clinical evaluation and total and specific IgE assay for the most common classes of inhalant and food allergens (grasses, house dust mite, cat dander, cow’s milk and egg white) at 2 different times (t) during pre-school age (t0, mean age 15 ± 3 months and t1, mean age 30 ± 3 months old) and then at intermittent times according to the clinical needs (mean age of follow-up 10 years). Asthma diagnosis was assessed at one follow-up visit performed during school-age. Univariate and multivariate logistic regression were used to determine the risk of asthma. Results: At follow-up visit, 39% of children had developed asthma. Of the variables compared, the presence of sensitization to more than one class of inhalant allergens at t1 was associated with asthma (P<.005). The multivariate analysis demonstrated that grass pollen [OR=3.2 (95%CI: 1.2, 8.7), P<.05] and cat sensitization [OR=2.7 (95%CI: 1.1, 7.3), P<.05] were independent risk factors for asthma. No relation was found between asthma and early food allergen sensitization. Conclusion: Our data showed that children with AD who develop sensitization to multiple classes of aeroallergens during early preschool (mean age 30 months old) are at increased risk for asthma during school age.