BOSTON — Obesity has little impact on the disease-related outcomes of asthma in children, despite the fact that being overweight is an established risk factor for the respiratory condition, reported Umit B. Emre, M.D.
Unlike adults, in whom obesity is associated with higher asthma morbidity, obese or overweight children with asthma have symptoms and morbidity that are “more or less comparable” with those of normal-weight children, Dr. Emre said in a presentation at the annual meeting of the American College of Allergy, Asthma, and Immunology.
Dr. Emre and colleagues at Beth Israel Medical Center in New York analyzed data from 85 children and adolescents who were evaluated for asthma at a community-based pediatric pulmonary practice from 1999 to 2003. Asthma was the primary diagnosis for all of the children included in the analysis, and there were no other diseases present. Baseline characteristics, including age, gender, and race, were similar across the group.
The investigators classified the children by asthma severity and by weight using standard body mass index measures. With respect to asthma severity, 32 of the patients were classified as having intermittent asthma, 42 had persistent mild asthma, and 11 had persistent moderate-severe asthma. In terms of weight status, 31 were classified as normal weight, 21 were overweight, and 33 were obese.
The disease severity proportions did not differ between normal, overweight, and obese children, said Dr. Emre. Drug use, emergency treatments, and lung-function test performance were also similar across the board.
Asthma severity, while not predicted by obesity, was itself a predictor of controller therapy use and emergency department visit and/or hospitalization. “As could be expected, rates of drug use and emergency care were highest for children classified as having persistent moderate to severe asthma,” Dr. Emre commented. “Weight classification was not a determinant for either of these outcomes.”
Weight also was not independently correlated with lung function in these patients. The mean forced expiratory volume in 1 second for both the overweight/obese and normal weight groups was approximately 83% of predicted flow, and the mean peak expiratory flow in midlung volume for both was approximately 77% of predicted volume, independent of body mass index.
The study may be limited by selection bias in that the patients were not randomly selected, and all those included had more serious asthma than that which might be seen in the normal pediatric practice, making it more difficult to detect differences that might be related to weight. “Or it may just be that the link becomes more significant over time, as other problems associated with obesity become more problematic, possibly exacerbating asthma symptoms,” he said.
To better understand the full impact of obesity on asthma in young patients, Dr. Emre and colleagues have undertaken a prospective study to address the inherent limitations to a retrospective analysis. “We're looking at different asthma-related disease outcomes, including quality of life, and are trying to detect any weight-based differences,” he noted.