(RxWiki News) The hazards of secondhand smoke to children are already clear in medical research, but such exposure is especially a problem for children with asthma or wheezing.
A recent study found that children with asthma or wheezing were more likely to be readmitted to the hospital within a year of a first admission if they had been exposed to tobacco smoke.
The exposure was measured based on a tobacco ingredient's presence in the children's blood or saliva.
Yet, asking parents or caregivers about a child's exposure to tobacco smoke did not provide sufficient information to know who might require readmission.
"Keep kids away from secondhand smoke."
This study was led by Judie A. Howrylak, MD, PhD, of the Division of Pulmonary, Allergy and Critical Care Medicine at Penn State Milton S. Hershey Medical Center in Pennsylvania.
The researchers aimed to understand possible links between tobacco smoke exposure and asthma in children.
The researchers followed 774 children, aged 1 to 16, for one year after they had been admitted to the hospital for asthma or severe wheezing.
The authors of this study wanted to learn which of the children were readmitted to the hospital during that year and how that compared with their exposure to tobacco smoke.
In addition to collecting information from caregivers about tobacco exposure at home, at another home or in the car, the researchers measured the amount of cotinine in children's blood and saliva.
Cotinine is an ingredient found in tobacco, and its presence in a person's body can be used to estimate that person's exposure to tobacco.
Of the original children followed, 619 had enough complete information regarding tobacco exposure for the researchers to analyze.
A little over half of the children were black, and about three quarters of them were on Medicaid.
Overall, 17 percent of the children were readmitted to the hospital for asthma or wheezing within one year of their first admission.
Of the children with complete tobacco exposure information, 35 percent had been exposed to tobacco smoke according to their caregivers.
However, 56 percent of them had been exposed based on cotinine levels in their blood, and 80 percent of them had high enough cotinine exposures in their saliva to show they had been exposed at least secondhand to tobacco.
In fact, 39 percent of the children whose caregivers said children didn't have tobacco exposure had cotinine detected in their blood.
In addition, 70 percent of the children whose caregivers reported no tobacco exposure had cotinine detected in their saliva.
The researchers did not find that children were more or less likely to be readmitted to the hospital if their caregiver had reported tobacco exposure, but the results differed for those with cotinine in their blood or saliva.
Children whose blood samples contained cotinine had 1.6 times greater odds of being admitted to the hospital again within a year of their first hospital visit, compared to children without cotinine levels in their blood.
Children whose saliva samples contained cotinine had 2.4 times greater odds of readmission to the hospital for asthma or wheezing, compared to children without cotinine in their saliva.
"We found that secondhand smoke exposure was common among children admitted for wheezing or asthma," the researchers concluded.
They found that being readmitted to the hospital for asthma or wheezing was specifically linked to tobacco exposure detected by cotinine levels in the blood or saliva.
However, parent or other caregiver reports of exposure to tobacco smoke for the child did not predict whether a child could expect to be readmitted to the hospital or not.
Having children's blood or saliva tested for levels of cotinine may therefore offer insights into whether the child's asthma or wheezing may require later hospitalization.
This study was published January 20 in the journal Pediatrics. The authors reported no potential conflicts of interest.
The research was funded by the National Institutes of Health, a Flight Attendance Medical Research Foundation Young Clinical Scientist Award and the National Institute of Environmental Health Sciences.