Factors affecting respiratory syncytial virus positive wheezing illnesses in infants

Abstract

Objective: Respiratory Syncytial Virus or RSV is the most common cause of lower respiratory tract infections in infants and young children. Often, the more severe the episode of RSV, the more likely wheezing will be present with the illness. Infants who experience wheezing with a viral infection may develop asthma in the future. The purpose of this study, therefore, is to determine if there is a difference in the incidence of RSV positive wheezing illnesses during infancy among infants who differ in length of exclusive breast or formula feeding. Extraneous variables such as gender of the infant, maternal history of allergy and asthma, smoking in the infant’s environment, and ethnicity of the infant are also thought to play a role in the development of respiratory illnesses. These variables will be examined in addition to breastfeeding to determine if they have an effect on the incidence of RSV positive wheezing illnesses, and counteract, conceal, or augment any protective effects of breastfeeding. Subjects: The subjects for this project included the 287 infants participating in the Childhood Origins of Asthma (COAST) project, a prospective, longitudinal study at the University of Wisconsin Asthma and Allergy Clinical Research Unit in Madison, Wisconsin being conducted to elucidate possible causes for asthma. Procedures: The Statistical Package for Social Sciences (SPSS) version 10.0 was utilized for data analysis. The Chi-Square procedure was employed to determine if length of exclusive breastfeeding is independent of gender, ethnicity, smoke exposure, and maternal history of allergy and/or asthma. Binary logistic regression analysis was applied to determine if a relationship exists among RSV and RSV positive wheezing illnesses and length of exclusive breastfeeding, gender of the infant, ethnicity of the infant, smoke exposure, and maternal history of allergy and/or asthma. Finally, multivariate logistic regression analysis was carried out to determine if the incidence of RSV and RSV positive wheezing illnesses were affected when examining all of the variables in combination with each other. Results: Neither formula feeding nor length of exclusive breastfeeding was associated with gender, ethnicity, or maternal history of allergy and/or asthma. Infants exposed to smoke were significantly less likely, however, to have been breastfed or were breastfed for shorter time periods (p = 0.043). With exclusive breastfeeding greater than or equal to six months serving as the reference category, no significant relationship was found between presence of RSV and never breastfeeding or exclusive breastfeeding less than six months. No significant connection was revealed between RSV positive wheezing illnesses and never breastfeeding or exclusive breastfeeding less than six months. Infants with a maternal history of both allergy and asthma were significantly more likely to have RSV positive wheezing illnesses when examined alone (p = 0.036) and while controlling for feeding history, gender, ethnicity, and smoke exposure (p = 0.032). Conclusions: As established by the results, this study demonstrates that breastfeeding, even for prolonged periods of time, does not seem to protect against wheezing illnesses in children with a maternal history of allergy and/or asthma. However, there is no reason to discourage families from this method of feeding. The general benefits of breastfeeding for both infants and mothers are simply too great to ignore.