Tobacco smoke exposure tied to readmission in asthmatics

Detectable serum and salivary cotinine-a biomarker of tobacco exposure-is common among children admitted for asthma or bronchodilator-responsive wheezing and is associated with readmission, a study in asthmatic youngsters showed. Caregiver reports of secondhand smoke exposure do not appear to be significant predictors of hospital readmissions, however.

At the study’s start, investigators interviewed the parents of 619 children admitted for asthma about their child’s exposure to tobacco and collected serum and saliva specimens, which were analyzed for cotinine levels. At baseline, 56.1% of the children had detectable serum cotinine and 79.6% had detectable saliva cotinine.

Only 35.1% of admitted children were exposed to tobacco, according to their parents, but among children whose parents reported no tobacco exposure, 39.1% had detectable serum cotinine levels and 69.9% had detectable salivary cotinine levels. African American children had the highest rates of detectable serum cotinine (61.1%) and salivary cotinine (86.8%). Higher parental incomes and educational levels were each associated with lower rates of detectable cotinine.

Children who had detectable serum or salivary cotinine were more likely to be readmitted within a year of the study’s start than children without detectable cotinine levels. Readmission rates for children with detectable serum cotinine were 19.6% compared with 12.9% for children without detectable serum cotinine. For salivary cotinine, the comparable readmission rates were 18.7% vs 8.7%, respectively (Howrylak JA, et al. Pediatrics. 2014;133[2]:e355-e362).

Commentary: The point here is not just that measured cotinine is a good test of tobacco exposure but also that parental history is not. If cheap, rapid, salivary cotinine levels were available in the office or at the bedside, they would offer a powerful objective tool for counseling families of children with asthma. Linking the results to likelihood of readmission might move loved ones to protect the asthmatic child from smoke wherever they are exposed to it. -Michael Burke, MD

Ms Freedman is a freelance medical editor and writer in New Jersey. Dr Burke, section editor for Journal Club, is chairman of the Department of Pediatrics at Saint Agnes Hospital, Baltimore, Maryland. He is a contributing editor for Contemporary Pediatrics. The editors have nothing to disclose in regard to affiliations with or financial interests in any organizations that may have an interest in any part of this article.