Cotinine in children admitted for asthma and readmission

To explore the relationship between tobacco smoke exposure (reported versus biomarker) and rates of readmission for children hospitalized for asthma.

We enrolled a prospective cohort of 774 children aged 1 to 16 years admitted for asthma or bronchodilator-responsive wheezing. The primary outcome was at least 1 asthma- or wheeze-related readmission within 1 year. Caregivers reported any tobacco exposure at home, in a secondary residence, or in the car. We measured serum and saliva cotinine levels with mass spectrometry. We used logistic regression to evaluate associations between tobacco exposure and readmissions.

A total of 619 children had complete tobacco exposure data; 57% were African American and 76% had Medicaid. Seventeen percent of children were readmitted within 1 year. Tobacco exposure rates were 35.1%, 56.1%, and 79.6% by report, serum, and saliva measures, respectively. Caregiver report of any tobacco exposure was not associated with readmission (adjusted odds ratio: 1.18; 95% confidence interval: 0.79-1.89), but having detectable serum or salivary cotinine was associated with increased odds of readmission (adjusted odds ratio [95% confidence interval]: 1.59 [1.02-2.48] and 2.35 [1.22-4.55], respectively). Among children whose caregivers reported no tobacco exposure, 39.1% had detectable serum cotinine and 69.9% had detectable salivary cotinine. Of the children with reported exposure, 87.6% had detectable serum cotinine and 97.7% had detectable salivary cotinine.

Detectable serum and salivary cotinine levels were common among children admitted for asthma and were associated with readmission, whereas caregiver report of tobacco exposure was not.