Background Exposure to environmental tobacco smoke (ETS) is known to increase the risk of respiratory tract infections (RTI). Some children, however, may be more susceptible to the harmful effects of ETS than others. We examined whether early atopic status (defined by elevated neonatal total IgE (tIgE) or symptoms of atopic dermatitis) modified the association between ETS exposure and RTI.
Methods The data of 2863 children from the Prevention and Incidence of Asthma and Mite Allergy birth cohort were collected to the age of 4 years. Neonatal tIgE was collected from a subset of 914 children, and clinical information by yearly parental questionnaires. The effect of pre- and/or postnatal ETS exposure, early atopic status and interaction between these factors was studied for various RTI.
Results Children with elevated tIgE or atopic dermatitis and prenatal ETS exposure have a strongly increased risk of frequent RTI (aOR 6.18 (95% CI 1.45 to 26.34) and 5.69 (2.01 to 16.04), respectively; interaction p=0.006 and p=0.14, respectively) compared to non-atopic children without prenatal ETS exposure. Similar results were seen for lower RTI and otitis. This effect was less evident for postnatal ETS.
Conclusion Early atopic status enhances the risk of RTI in children with prenatal ETS exposure. This suggests that host factors modify the association between ETS and RTI.
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Funding The Prevention and Incidence of Asthma and Mite Allergy study is supported by the Netherlands Organization for Health Research and Development (ZON-MW), the Netherlands Asthma Fund, the National Institute of Public Health and the Environment, and the Ministry of Housing, Urban Planning, and the Environment. Jopje Ruskamp is supported by the Wilhelmina Research Fund of the UMC Utrecht.
Competing interests None.
Ethics approval The study was approved by the Institutional Review Board.
Provenance and peer review Not commissioned; externally peer reviewed.
Patient consent Parental consent obtained.