Asthmatic children living in asthma hotspots were twice as likely to experience exercise-induced wheeze as asthmatic children in neighborhoods with lower asthma rates, according to a New York City study.
The study enrolled 195 middle-income children with asthma, ages 7 and 8, living in areas with varying asthma prevalence throughout the city. The children were given a clinical evaluation, and their caregivers completed a health survey that included whether they had experienced exercise-induced wheeze one or more times in the past year.
Overall, 43% of the children had experienced exercise-induced wheeze. Those living in asthma hotspots were twice as likely to have experienced symptoms after exercise and more likely to have visited their physician in a hurry or an ED because of breathing problems, even after adjusting for neighborhood, income and other factors.
“Exercise-induced wheeze is very uncomfortable for children,” Timothy Mainardi, MD, who conducted the study as a fellow at Columbia University Medical Center and practices at Hudson Allergy, said in a news release. “It can present rapidly after any strenuous activity and lead quickly to respiratory symptoms, so it is not surprising that it is a factor in ER visits.”
Mainardi and his colleagues, also including researchers from Dartmouth-Hitchcock Medical Center, found that a third of the children experiencing exercise-induced wheeze had not used an inhaler prior to exercising. “The good news is that these symptoms are preventable,” Mainardi said. “Parents should talk with their doctor so they can be ready with a plan, including the use of appropriate medication such as a bronchodilator inhaler prior to exercise.”
Addressing neighborhood disparities in asthma-related ED visits has been a public health priority for many years. To help explain these differences, the researchers first examined whether asthma was more severe in low-income, high-asthma neighborhoods, and found it was not.
“Lung function, airway inflammation, allergy to common asthma triggers and symptom frequency were similar no matter where the child lived,” said Matthew Perzanowski, PhD, the studys senior author and associate professor of environmental health sciences at Columbias Mailman School of Public Health.
By process of elimination, the researchers focused on one particular manifestation of the disease: rapid airway constriction brought on by exercise.
Exactly why asthma hotspots have higher rates of this symptom remains a mystery, the researchers said. Although inadequate use of a bronchodilator inhaler prior to exercise was a factor, it did not fully explain the findings. Allergens and air pollution related to fossil fuel burning were not found to be factors. Neither were differences in physical activity, obesity or neighborhood conditions such as the number of parks.
“Exercise-induced symptoms may identify a distinct population of asthmatics with causes for their exacerbation yet to be determined,” Perzanowski said. “The important lesson is that with greater awareness and treatment, we can hope to prevent those unscheduled visits to the doctor and trips to the ER.”
The study appeared Dec. 17 on the website of the journal Pediatrics. The study abstract is available at http://pediatrics.aappublications.org/content/early/2012/12/12/peds.2012-1072.abstract.