Obesity's effect on asthma extends to diagnostic criteria.

Pubmed ID: 28624608

Pubmed Central ID: PMC6076889

Journal: The Journal of allergy and clinical immunology

Publication Date: March 1, 2018

Affiliation: Department of Medicine, University of Arizona, Tucson, Ariz.

MeSH Terms: Humans, Male, Adult, Female, Middle Aged, Obesity, Asthma, Leukocyte Count, Nitric Oxide, Inflammation, Biomarkers, Eosinophils, Immunoglobulin E

Grants: P30 ES006694, U10 HL074227, T32 AI007062, U10 HL074208, U10 HL074218, U10 HL074204, U10 HL074231, U10 HL074225, U10 HL074073, U10 HL074212, U10 HL074206, U10 HL098107

Authors: Anstrom KJ, Yang S, Israel E, Zhang S, Lugogo N, Green CL, Agada N, Meghdadpour S, Zhou R, Martin R, Lemanske RF, Boushey H, Lazarus SC, Wasserman SI, Castro M, Calhoun W, Peters SP, DiMango E, Chinchilli V, Kunselman S, King TS, Icitovic N, Kraft M

Cite As: Lugogo N, Green CL, Agada N, Zhang S, Meghdadpour S, Zhou R, Yang S, Anstrom KJ, Israel E, Martin R, Lemanske RF Jr, Boushey H, Lazarus SC, Wasserman SI, Castro M, Calhoun W, Peters SP, DiMango E, Chinchilli V, Kunselman S, King TS, Icitovic N, Kraft M. Obesity's effect on asthma extends to diagnostic criteria. J Allergy Clin Immunol 2018 Mar;141(3):1096-1104. Epub 2017 Jun 15.

Studies:

Asthma Clinical Research Network Trial (ACRN) - Best Adjustment Strategy for Asthma in Long Term (BASALT) and Tiotropium Bromide as an Alternative to Increased Inhaled Corticosteroid in Patients Inadequately Controlled on a Lower Dose of Inhaled Corticosteroid (TALC)

Abstract

BACKGROUND: The use of inflammatory biomarkers to delineate the type of lung inflammation present in asthmatic subjects is increasingly common. However, the effect of obesity on these markers is unknown. OBJECTIVES: We aimed to determine the effect of obesity on conventional markers of inflammation in asthmatic subjects. METHODS: We performed secondary analysis of data from 652 subjects previously enrolled in 2 Asthma Clinical Research Network trials. We performed linear correlations between biomarkers and logistic regression analysis to determine the predictive value of IgE levels, blood eosinophil counts, and fraction of exhaled nitric oxide values in relationship to sputum eosinophil counts (>2%), as well as to determine whether cut points existed that would maximize the sensitivity and specificity for predicting sputum eosinophilia in the 3 weight groups. RESULTS: Overall, statistically significant but relatively weak correlations were observed among all 4 markers of inflammation. Within obese subjects, the only significant correlation found was between IgE levels and blood eosinophil counts (r = 0.33, P < .001); furthermore, all other correlations between inflammatory markers were approximately 0, including correlations with sputum eosinophil counts. 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 biomarkers of inflammation significantly predicted the presence of high sputum eosinophil counts. Obese asthmatic subjects have lower cut points for IgE levels (268 IU), fraction of exhaled nitric oxide values (14.5 ppb), and blood eosinophil counts (96 cells/μL) than all other groups. CONCLUSIONS: In obese asthmatic subjects conventional biomarkers of inflammation are poorly predictive of eosinophilic airway inflammation. As such, biomarkers currently used to delineate eosinophilic inflammation in asthmatic subjects should be approached with caution in these subjects.