Obesity’s Impact on Asthma Extends to Diagnostic Criteria

Publication date: Available online 15 June 2017
Source:Journal of Allergy and Clinical Immunology
Author(s): Njira Lugogo, Cynthia L. Green, Noah Agada, Siyi Zhang, Susanne Meghdadpour, Run Zhou, Siyun Yang, Kevin J. Anstrom, Elliot Israel, Richard Martin, Robert F. Lemanske, Homer Boushey, Stephen C. Lazarus, Stephen I. Wasserman, Mario Castro, William Calhoun, Stephen P. Peters, Emily DiMango, Vernon Chinchilli, Nikolina Icitovic, Susan Kunselman, Tonya S. King, Monica Kraft
BackgroundThe use of inflammatory biomarkers to delineate the type of lung inflammation present in asthma is increasingly common. However, the impact of obesity on these markers is unknown.ObjectivesWe aimed to determine the impact of obesity on conventional markers of inflammation in asthma.MethodsWe performed secondary analysis of data from 652 patients previously enrolled in two ACRN trials. We performed linear correlations between biomarkers and logistic regression analysis to determine the predictive value of IgE, blood eosinophils and FeNO in relationship to sputum eosinophils (>2%), as well as to determine if cut points existed that would maximize the sensitivity and specificity for predicting sputum eosinophilia in the three weight groups.ResultsOverall, statistically significant but relatively weak correlations were observed among all four markers of inflammation. Within obese subjects, the only significant correlation found was between IgE and blood eosinophils (r=0.33, p<0.001); furthermore, all other correlations between inflammatory markers were approximately 0, including correlations with sputum eosinophils. In addition, the predictive value of each biomarker alone or in combination was poor in obese subjects. In fact in obese subjects, none of the inflammation biomarkers significantly predicted the presence of high sputum eosinophils. Obese asthma subjects have lower cut points for IgE, (268IU), FeNO (14.5ppb) and blood eosinophils (96 cells/ul) than all other groups.ConclusionsIn obese asthma, conventional biomarkers of inflammation are poorly predictive of eosinophilic airway inflammation. As such, biomarkers currently used to delineate eosinophilic inflammation in asthma should be approached with caution in these patients.

Graphical abstract

Teaser

Obesity is associated with decreased sensitivity of blood eosinophils, IgE and FeNO in characterizing eosinophilia. Reliance on peripheral markers to make decisions regarding therapies targeting eosinophilia should therefore be approached with caution in obese asthma.


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