Purpose of the Study. To determine if there are differences in risk factors and measures of severity between children with different asthma phenotypes.
Study Population. The authors reviewed data from children aged 6 to 16 years derived from the Third National Health and Nutrition Examination Survey.
Methods. The authors used questionnaire and skin-prick–testing data to separate children into the following categories: atopic asthma, nonatopic asthma, resolved asthma, frequent respiratory symptoms with no asthma diagnosis, and normal. Multivariate regression was used to determine if demographic or potential risk factors varied between phenotypes and whether measures of severity varied by phenotype.
Results. A total of 4.8% of children had atopic asthma, 1.9% had nonatopic asthma, 3.4% had resolved asthma, and 4.3% had frequent respiratory symptoms. Mean BMI was higher among children with nonatopic asthma, whereas prenatal maternal smoking was a risk factor for resolved asthma. Atopic and nonatopic asthma were similar for most measures of asthma severity (eg, medication use and lung function), and relatively few children in either group were receiving inhaled corticosteroids (5%–10%). Patients with resolved asthma had fewer symptoms but lung-function impairment similar to that seen with current asthma, whereas children with frequent respiratory symptoms but no asthma diagnosis had normal lung function.
Conclusions. The authors conclude that asthma risk factors and measures of severity vary between children with different asthma phenotypes.
Reviewer Comments. Studies of children and adults have identified several unique phenotypes of asthma that share the feature of chronic and/or recurrent airflow obstruction. Accurate categorization is crucial in efforts to define genetic and environmental risk factors for asthma, and this work uses a very large national database to help establish environmental correlates to asthma subgroups in children. Notably, resolved asthma was linked to prenatal exposure to tobacco smoke and also to persistent impairment in lung function. Because environmental and lifestyle factors are almost certainly behind the rise in asthma prevalence, this line of research is clearly valuable from a public health perspective.
- Copyright © 2006 by the American Academy of Pediatrics