A new paper claims that exposure to secondhand smoke at home or in the car increases the odds of children being readmitted to the hospital within a year of being admitted for asthma.

It seems like pretty obvious correlation-causation that more smoke of any kind would be bad for asthmatic kids but the paper says their new estimate should be used as data for more smoking cessation efforts, to reduce the likelihood of future hospitalizations.

The exposure was determined by measuring cotinine - an alkaloid in tobacco and a metabolite of nicotine (as you may have noticed, cotinine is an anagram of nicotine) - in the blood and saliva of over 600 children. Cotinine is a substance produced when the body breaks down nicotine and provides a scientific assessment of tobacco exposure. 

The researchers at Cincinnati Children's Hospital Medical Center and Penn State Milton S. Hershey Children's Hospital found that there was no correlation between caregiver report of tobacco exposure and readmission. Yet the measurement of cotinine in the blood and saliva demonstrated a readmission risk in children exposed to secondhand smoke more than twice that of children not exposed and the authors note that this means self-reporting is not all that accurate.

"The ability to measure serum and salivary cotinine levels presents the possibility of an objective measure that can be obtained when a child is seen in the emergency department or in the hospital
and may be used to predict future hospitalizations," says Robert Kahn, MD, MPH, associate director of general and community pediatrics at Cincinnati Children's and senior author of the study. "Such a measure for exposure to tobacco smoke could be used to target specific interventions at caregivers of those children before discharge from the hospital. Several interventions, including parental counseling and contact with the primary care physician, could be adopted in clinical practice."

Because low-income and minority children are in families that smoke more, the Greater Cincinnati Asthma Risks Study focuses on hospital readmissions there. The researchers looked at children between the ages of 1 and 16 admitted to Cincinnati Children's between August 2010 and October 2011. Serum and salivary cotinine levels were taken during their hospital stay, and their primary caregivers were asked about tobacco exposure. All children were followed for at least 12 months to see if they were readmitted to the hospital. 

"Of the 619 children in the study, 76 percent were covered by Medicaid," says Judie Howrylak, MD, PhD, a physician at Hershey Children's and lead author of the study. "Certainly there could be a financial incentive for insurance companies to help caregivers quit smoking, rather than pay the downstream costs of a future asthma readmission."

Insurance companies? The government pays for Medicaid, insurance companies are not worried about spending even more money to tell people what they have been told for 50 years - that smoking is bad.