Asthma affects millions of children in the U.S., making it the most common chronic condition among children. And the air around the homes of some children with asthma may be affecting their condition.
A recent study found that traffic-related air pollution was tied to increased odds of white children being readmitted to the hospital for asthma within 12 months of initially being hospitalized for the same condition.
The researchers discovered that air pollution exposure and hospital readmission were not significantly linked for the African-American children, even though they had higher levels of hospital readmission overall. This finding suggests that other social and environmental factors not considered in this study came into play.
The lead author of this study was Nicholas C. Newman, DO, MS, from the Division of General and Community Pediatrics in the Department of Pediatrics of the Cincinnati Children's Hospital Medical Center in Cincinnati, Ohio.
The study included 758 children between the ages of 1 and 16 years old who had been admitted to the Cincinnati Children's Hospital Medical Center for asthma between August 2010 and October 2011. A total of 58 percent of these participants were African American, 32 percent were white, and 65 percent were boys.
The researchers used hospital billing data to look for hospital readmissions for asthma within 12 months of the initial hospitalization date.
The children's level of exposure to air pollution was assessed by using a previously developed model that sampled air at 27 places in the Cincinnati area between 2001 and 2006. The children's exposure levels were based on their home addresses.
Half of the children had high air pollution exposure and half had low exposure. The findings showed that 19 percent of the children were readmitted to the hospital for asthma.
Of those readmitted, 72 percent were African-American children, 94 percent came from households with a low annual income (less than $60,000 per year), and 53 percent of their mothers had not graduated high school.
In addition, 57 percent of the readmitted children were on asthma control medication.
The researchers determined that level of air pollution exposure and readmission was not significantly associated for the whole study population. However, when analysis was limited to the white children there was a significant association.
White children who were exposed to high levels of air pollution were three times more likely to be readmitted to the hospital for asthma than white children who were exposed to low levels of air pollution.
Even though the African-American children had higher rates of readmission overall, the association between air pollution and readmission was non-significant. The researchers believe that social and environmental factors other than air pollution were relevant and need to be considered in future research.
"This study adds to the evidence that air pollution exposure worsens the health of children with asthma," said co-author Robert Kahn, MD, MPH. "We hope that this study can inform public policy. It may also suggest ways to personalize patient care based on environmental risks."
The estimated annual cost of childhood asthma due to air pollution and other environmental factors is $2.2 billion.
This study had some limitations. First, the study population was recruited from a single institution. Second, there were too small of samples of other racial groups. Third, air pollution exposure was based on estimates determined by an index that was developed years before the study period. Fourth, the children may have moved to a different residential location during the study. Lastly, diagnosing asthma in young children can be difficult and is often misclassified.
This study was published on March 27 in The Journal of Pediatrics.
The National Institutes of Health, the National Institute of Allergy and Infectious Diseases and the National Center for Advancing Translational Sciences provided funding.