Recurrent respiratory tract infections during the first 3 years of life and atopy at school age.

Abstract

The hypothesis that infections reduce the risk of atopy was investigated by estimating the association between recurrent respiratory tract infections during the first 3 years of life and atopy at school age. According to surveys in three different areas of Norway, children were classified into three groups: asthma, wheeze without asthma (wheeze), and no asthma/no wheeze. The skin prick test (SPT) was conducted on a stratified random sample of children (n = 502). The outcome was at least one positive SPT. The exposure variable was retrospective parental report of respiratory tract infections during the first 3 years of life. Infections were negatively associated with atopy, crude odds ratio (cOR) = 0.3, 95% confidence interval (95% CI) 0.1-0.7, in the asthma group. A similar association was present in children with wheeze cOR = 0.4 (95% CI 0.1-1.2). The number of siblings was not associated with atopy in any group. Infections remained negatively associated with atopy in children with asthma, aOR = 0.3 (95% CI 0.1-0.7), in a logistic regression model adjusting for confounding factors. A similar pattern was present in the wheeze group. Recurrent respiratory tract infections during the first 3 years of life are negatively associated with atopy at school age in children with asthma.