WEDNESDAY, Aug. 7 (HealthDay News) -- Overweight and obese kids are more likely to struggle with asthma than kids of normal weight, according to a new review of more than 623,000 children.
Researchers found that children carrying extra weight are between 1.16 to 1.37 times more likely to develop asthma than normal-weight kids, with the risk growing as their body-mass index -- a measure of body fat encompassing height and weight -- increases.
Obese children also experience more frequent and severe episodes of asthma, requiring more medical attention and drug therapy, found the study in the Aug. 7 issue of the American Journal of Epidemiology.
For example, heavier kids required more visits to the doctor to treat their asthma, and needed to use inhalers more often to help restore normal breathing.
Inflammation caused by body fat is suspected to be one factor in the kids' increased risk of asthma, said study lead author Mary Helen Black, of the department of research and evaluation at Kaiser Permanente Southern California.
The extra pounds also might affect the severity of asthma by placing additional weight on a child's chest, Black said.
"Overweight and obese youths have greater perceived symptoms of asthma," she said. "When they have difficulty breathing, it seems more extreme to them than to kids with normal weight." This could be due to the added weight constricting their breathing.
Asthma is the most common chronic childhood illness in the United States, affecting one of every 10 kids, according to study background information.
For the study, the researchers examined electronic health records maintained by Kaiser Permanente for 623,358 children and classified them from normal weight to extremely obese based on their height and weight.
The link between asthma and obesity was particularly pronounced among moderately and extremely obese girls between 6 and 10 years old, who had between 1.36 and 1.56 times higher risk of asthma than normal-weight girls their age.
Moderately and extremely obese Asian-Pacific Islander children also were inordinately affected, running between 1.41 and 1.67 times higher risk of asthma, the investigators found.
The new study confirms a common-sense link between the effects of obesity and the causes of asthma, said Dr. Jacqueline Eghrari-Sabet, an allergy and asthma specialist in Gaithersburg, Md., and a fellow of the American Academy of Allergy, Asthma & Immunology. She was not involved with the study.
"Really you could have figured this out if you lined up all of the boxes neatly on your table," Eghrari-Sabet said. "Fat is a huge reservoir of toxins. Toxins can of course cause inflammation. This is kind of like, what do you expect?"
Eghrari-Sabet noted that the inflammatory response caused by obesity already has been linked to other chronic conditions such as heart disease.
"If we explored this idea a little further: Is that the same cardiac disease you see in the adult? It would make you take the asthma in the young person so much more seriously because the problem is, so many people do not take asthma seriously," she said. "If you said your asthma is linked to heart disease, you would get that kid treated so much faster for asthma."
Study author Black said physicians and families should monitor overweight and obese children closely for signs of asthma.
"If they already have asthma, parents should think about their medication regimen and do everything they can to prevent some of these symptom exacerbations [flare-ups] from happening, knowing that kids who are obese are more likely to have these exacerbations," Black said.
Visit the American Academy of Allergy, Asthma & Immunology to learn more about childhood asthma.
SOURCES: Mary Helen Black, Ph.D., department of research and evaluation, Kaiser Permanente Southern California; Jacqueline Eghrari-Sabet, M.D., allergy and asthma specialist, Gaithersburg, Md., and fellow, American Academy of Allergy, Asthma & Immunology; Aug. 7, 2013, American Journal of Epidemiology