Breast-feeding, aeroallergen sensitization, and environmental exposures during infancy are determinants of childhood allergic rhinitis

Background: Infant predictors of early childhood allergic rhinitis (AR) are poorly understood. Objective: We sought to identify environmental exposures and host factors during infancy that predict AR at age 3 years. Methods: High-risk children from greater Cincinnati were followed annually from ages 1 to 3 years. AR was defined as sneezing, runny, or blocked nose in the prior 12 months and a positive skin prick test (SPT) response to 1 or more aeroallergens. Environmental and standardized medical questionnaires determined exposures and clinical outcomes. Primary activity area dust samples were analyzed for house dust endotoxin (HDE) and (1-3)beta-D-glucan. Fine particulate matter sampled at 27 monitoring stations was used to estimate personal elemental carbon attributable to traffic exposure by using a land-use regression model. Results: Of 361 children in this analysis, 116 had AR, and 245 were nonatopic and nonsymptomatic. Prolonged breast-feeding in African American children (adjusted odds ratio [aOR], 0.8; 95% CI, 0.6-0.9) and multiple children in the home during infancy was protective against AR (aOR, 0.4; 95% CI, 0.2-0.8). Food SPT response positivity and tree SPT response positivity in infancy increased the risk of AR at age 3 years (aOR of 4.4 [95% CI, 2.1-9.2] and aOR of 6.8 [95% CI, 2.5-18.7], respectively). HDE exposure was associated with AR; the effect was dependent on exposure level. Elemental carbon attributable to traffic and environmental tobacco smoke exposure showed no effect on AR. Conclusion: Prolonged breast-feeding in African American subjects and multiple children in the home during infancy reduced the risk of AR at age 3 years. SPT response positivity to food and tree allergens enhanced risk. The HDE effect on AR was related to exposure. (J Allergy Clin Immunol 2010;125:1054-60.)