Young children with asthma may be more likely to become obese by adolescence than their peers who don't have asthma, a new study suggests.
Researchers examined data on 2,171 non-obese children in kindergarten and first grade and found they were 51 percent more likely to become obese over the next decade if they had asthma.
When children with asthma used rescue medications, however, their risk of becoming obese dropped by 43 percent, researchers report in the American Journal of Respiratory and Critical Care Medicine.
When children with asthma used rescue medications, however, their risk of becoming obese dropped by 43 percent
"Asthmatic children may have increased risk of obesity because of a lack of physical activity due to poorly controlled asthma, potential adverse effects from long-term use of corticosteroid medications or common genetic factors," said lead study author Zhanghua Chen, from the Keck School of Medicine at the University of Southern California in Los Angeles.
"The protective effects of rescue medication on obesity risk in our study may be due to the direct effects of the rescue medication or it could be an indicator of better controlled asthma," Chen added. "However, the exact mechanism is unknown."
To examine the connection between childhood asthma and obesity, Chen and colleagues followed students from eight southern California communities from elementary school through high school graduation.
Kids had medical exams at least once every two years during the study, and parents or children also completed periodic health questionnaires that asked about asthma, respiratory illness, exercise and family characteristics.
At the start of the study, 13.5 percent of the children had asthma.
They were followed for up to 10 years, and for an average of about seven years.
None of the kids was obese at the start of the study, but by the end almost 16 percent of them were obese.
The researchers accounted for a number of factors that might have influenced the results, including whether the children had health insurance or were overweight at enrollment, ethnicity, family income, smoking exposure at home and physical activity.
Even after considering these factors, asthma was associated with an increased risk of obesity. These factors also didn't explain why using asthma rescue medications might mean a reduced risk of obesity.
Long-term controller medicines for asthma were not associated with a lower risk of obesity for kids with asthma.
Limitations of the study include the reliance on parents to report asthma diagnosis as well as limited information about exercise and no data on diet, the authors note.
There has long been an association between asthma and obesity, but the exact reasons for this aren't certain, said Dr. David Stukus, an allergy and immunology specialist at Nationwide Children's Hospital in Columbus, Ohio, who wasn't involved in the study.
"Many studies have shown obese children are more prone to develop asthma, whereas some have shown the reverse," Stukus added by email. "This study adds to the pool of data supporting the link between the two but was not designed to determine any type of cause and effect relationship."