Predictors of Childhood Allergic Rhinitis

Abstract

Source: Codispoti C, Levin L, LeMasters G, et al. Breast-feeding, aeroallergen sensitization, and environmental exposures during infancy are determinants of childhood allergic rhinitis. J Allergy Clin Immunol. 2010; 125(5): 1054– 1060; doi: 10.1016/j.jaci.2010.02.004Investigators from Cincinnati Children’s Hospital and the University of Cincinnati sought to evaluate the combined effects of host factors and outdoor and indoor environmental exposures on the development of childhood allergic rhinitis (AR). Participants included a prospective cohort of children born to atopic parents from the greater Cincinnati area and followed annually until age 3 years. Infants were enrolled in the study if either parent had atopy and at least one positive skin prick test (SPT).The families returned for a comprehensive study visit at ages 1 and 3 years. The infants underwent a physical examination and SPT for 15 aeroallergens, egg, and milk. Parents completed a medical history and home environmental questionnaire. Child respiratory symptoms were captured using items adapted from the validated International Study of Asthma and Allergies in Childhood questionnaire. Primary outcome was the presence of AR at age 3 years defined by parental report of no upper respiratory infection symptoms and a positive SPT to one or more aeroallergens. Children with AR were compared to children without symptoms and with a negative SPT.Additional study evaluations included house dust endotoxin (HDE) at 8 months of age, outdoor traffic exposure estimation, elemental carbon counts attributable to traffic, and pollen counts. Additional variables included smoke exposure, breastfeeding duration, household income, dog exposure, and number of children in the home at 1 year of age.At age 3 years, 606 children completed the evaluations and SPT (21.5% African American, 78.6% non-African American). A total of 116 (19%) children had AR and 245 (40%) were nonatopic and asymptomatic. These 361 children comprised the case and comparison groups. Of the remaining children, 151 were atopic and asymptomatic and 94 were nonatopic but symptomatic.Univariate analysis of factors associated with AR at age 3 years included birth during the spring or summer months, a positive SPT to milk, egg, or both, and a positive SPT to any tree pollen in infancy. Prolonged breastfeeding duration (at least four months) was only protective in African American subjects (Adjusted OR=0.8; 95% CI, 0.6–0.9). Development of AR was associated with HDE with concentrations between 36.6 and 244.7 EU/mg. No association with AR was found for elemental carbon attributable to traffic, environmental tobacco smoke exposure, cat allergen levels, number of dogs in the home, fungal spore, or ragweed, tree, or grass pollen counts. Multivariate analysis was similar to the univariate analysis except that more than one child in the home during infancy was found to be protective against AR (Adjusted OR=0.4; 95% CI, 0.2–0.8). The authors conclude that multiple risk factors exist for childhood AR, that SPT is valuable in assessing that risk, and that African American infants are protected by prolonged breastfeeding.The increased prevalence of allergic diseases has stimulated research to identify potential disease-modifying measures. Studies have been inconclusive in identifying effective preventative measures such as avoidance of cat and dog allergens, gradual introduction of solid foods, and avoidance of maternal smoking.The belief that breastfeeding should be recommended for primary prevention of allergic disease is widespread. Exclusive breastfeeding beyond four months of age reduces the development of atopic disease in early life, but the long-term benefits are in question.1 One study has suggested that breastfeeding increases both asthma and allergen sensitization in adult life, but weighing the study’s findings is difficult because the breastfeeding was not always exclusive.2 Another breastfeeding study demonstrated a protective effect on infantile wheezing of breastfeeding in early life but increased asthma incidence in older atopic children.3 There is evidence that food allergies in infancy are a risk factor for the development of both allergic rhinitis and asthma.4Most breastfeeding studies do not take into account additional environmental and host factors in the development of allergic diseases. The current study is the first to suggest that prolonged breastfeeding in African American subjects may have a protective effect on the development of allergic rhinitis. Follow-up studies of this birth cohort to determine what proportion eventually develop asthma or other atopic diseases will be of interest.