The Relationship Between Tobacco Smoke Exposure and Airflow Obstruction in US Children: Analysis of the National Health and Nutrition Examination Survey (2007-2012).

Abstract

It has been difficult to determine the individual impact of prenatal and postnatal tobacco smoke exposure (TSE) on childhood lung function, as children are often exposed to both. The goal of this study was to determine the association between current TSE and airflow obstruction while adjusting for self-reported prenatal TSE. Children aged 6 to 11 years who participated in the National Health and Nutrition Examination Survey (2007-2012) who had serum cotinine levels measured and spirometry performed were included. Logistic regression was used to determine the association between log-transformed serum cotinine level and airflow obstruction while adjusting for confounders; the analysis was then stratified according to asthma status. The final model included both log-transformed serum cotinine level and prenatal exposure as covariates. The sample consisted of 2,070 children; 9.6% had airflow obstruction. The association between cotinine levels and airflow obstruction was significant in an unadjusted analysis (OR, 1.12 [95% CI, 1.02-1.23]). In the multivariate analysis with both exposures included as covariates, serum cotinine level was not significantly associated with airflow obstruction (OR_adj, 1.07 [95% CI, 0.94-1.21]), and no association was seen in children with asthma and nonasthmatic children. Prenatal smoking was associated with airflow obstruction in children with asthma (OR_adj, 2.51 [95% CI, 1.08-5.79]) but not in nonasthmatic children (OR_adj, 1.08 [95% CI, 0.53-2.18]). Current TSE was not independently associated with airflow obstruction in school-aged children. Prenatal TSE was associated with airflow obstruction in children with asthma. Repeated studies into potential mediators and confounders of this relationship are needed.