Poor asthma control may be overestimated in obese children
Published Online: January 2013
The prevalence of asthma in children is steadily increasing along with the “obesity epidemic,” leading to speculations about the biological linkages between the two disorders. While a growing body of literature supports the role of obesity in the modulation of asthma severity and control in adults, other studies have shown that obesity is associated with respiratory symptoms independent of asthma and therefore may contribute to asthma misdiagnosis. Because the vast majority of previous studies have focused on adults, the degree to which obesity contributes to asthma control in children is unclear.
In a recent issue of The Journal of Allergy and Clinical Immunology: In Practice, Sah et al. examined the relationship between obesity and asthma control in children 6-17 years of age with physician-diagnosed asthma enrolled in the National Heart, Lung and Blood Institute’s Severe Asthma Research Program at Emory University in Atlanta, Georgia. Children underwent extensive phenotypic characterization consisting of questionnaires, plethysmography, exhaled nitric oxide determination, and venipuncture for Th1/Th2 cytokines. Asthma control was defined according to pre-specified thresholds for lung function and symptom frequency as outlined in the National Asthma Education and Prevention Panel Expert Panel Report-3 (EPR-3).
Of the 269 children included in the analysis, 58 (22%) were overweight and 67 (25%) were obese. No associations between obesity and the composite outcome of asthma control were noted, even after adjusting for the potential confounding effects of age and sex. However, obese children were more likely to report non-specific asthma symptoms such as dyspnea more than twice weekly (adjusted OR 2.65, 95% CI 1.45 – 4.85) and nocturnal awakenings from asthma more than twice monthly (adjusted OR 1.89, 95% CI 1.06 – 3.55). Obese children also had significantly impaired quality of life, greater healthcare utilization and an increased frequency of glucocorticoid bursts, although no differences in pulmonary function were observed aside from lower functional residual capacity. Obese children with uncontrolled asthma further had decreased expression of IL-5, IL-10 and IL-13 but distinct patterns of Th1 versus Th2 polarization were not observed.
These findings suggest that obese children with asthma may experience more non-specific respiratory symptoms such as dyspnea that are associated with increased healthcare utilization and decreased quality of life in the absence of clear Th1 or Th2 polarization. Careful assessment of airway physiology as well as symptoms is warranted in the evaluation of obese children with respiratory symptoms to minimize over-treatment.
The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.