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.