Background: The natural history of allergic disease and its potential for prevention merit close examination because of the explosive worldwide increase in the prevalence and morbidity of atopic disorders. This study examines the development of atopy at age 7 years in 165 children in a high-risk cohort, previously reported from birth to age 4 years.
Methods: In this prospective, randomized, controlled study of food allergen avoidance in infancy, the prophylactic-treated group consisted of infants whose mothers avoided cow's milk, egg, and peanut during the last trimester of pregnancy and lactation and who, themselves, avoided cow's milk until age 1 year (casein hydrolysate supplementation before age 1), egg until age 2 years, and peanut and fish until age 3 years. The control group consisted of maternal/infant pairs who followed standard feeding practices.
Results: Despite a significant reduction in food allergy and milk sensitization before age 2 years, none of the following differed between the groups at age 7 years: food allergy, atopic dermatitis, allergic rhinitis, asthma, any atopic disease, lung function, food or aeroallergen sensitization, serum IgE level, or presence of nasal eosinophils or nasal basophilic cells. Children with food allergy by 4 years evidenced higher 7-year (current) prevalences of allergic rhinitis and asthma (p < 0.01). Atopic diseases/parameters at age 7 years were shown, by multivariate analysis (p < 0.05), to be associated with several genetic and environmental risk factors (male gender, maternal nonwhite ethnicity and asthma, and household smoking), as well as predictive atopic markers during infancy (elevated serum IgE level; egg, cow's milk, and peanut sensitization; and nasal eosinophils and nasal basophilic cells).
Conclusions: These findings help to: (1) elucidate the natural history of atopic disease in high-risk children; (2) document the progression of allergy from atopic dermatitis, food allergy, and food sensitization to respiratory allergy and aeroallergen sensitization despite food allergy prevention in infancy; (3) identify allergy predictive markers; and (4) expand our appreciation of the interactions of genetic and environmental factors in the development of atopy.