SELECTED ARTICLES FROM THE RECENT LITERATURE 2004
9/21/04
Relationship between obesity and asthma
Summary
Background - Epidemiologic studies suggest an increased prevalence of asthma in obese subjects. However, the reason for this association is not well defined.
Findings - To help understand mechanisms involved in the obesity-asthma relationship, Leung et al of the Chinese University of Hong Kong explored the possible relationship between obesity and the airways inflammation that characterizes asthma. They carried out a cross-sectional study in 92 asthmatic children and 23 age-matched healthy controls. They found that exhaled nitric oxide (ENO) and leukotriene B4 (LTB4) levels were significantly higher in asthmatics than in controls (p<0.0001). However, there was no correlation between ENO or exhaled LTB4 levels and the presence of obesity in the asthmatics. ENO (but not LTB4) levels did correlate with age of the subjects, blood eosinophil counts, plasma total IgE levels and the degree of decrease in FEV-1 values of individual asthmatic subjects. Conclusion - Patterns of markers of airway inflammation are not significantly different in obese and non-obese asthmatic children.
Reference
Pediatr Allergy Immunology 2004;15:344-50
Editor's Comments
It has been a common impression that childhood asthma is more common in obese subjects. The findings described above suggest that this increased frequency of asthma symptomatology is not due to a greater degree of airways inflammation. It could be that some of the symptoms leading to an asthma diagnosis are due to a decreased respiratory reserve in such obese individuals. In a previous study (Thorax 2001;56:4-8 ), the authors concluded that subjects with severe obesity reported more wheeze and shortness of breath which may suggest a diagnosis of asthma. However, their levels of atopy, airway hyper-responsiveness, and airway obstruction did not support the suggestion of a higher prevalence of asthma in this group. It has been shown recently that the levels of physical exercise are frequently lower in asthmatic children than in age- related peers. Perhaps this may contribute to obesity as well as decreased respiratory reserve, leading to increased asthma symptomatology.
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