Asthma-COPD overlap (ACO) is a common clinical syndrome, yet there is no single objective definition. We hypothesized that immunoglobulin E (IgE) measurements could be used to refine the definition of ACO. In baseline plasma samples from 2870 participants in the COPD Genetic Epidemiology (COPDGene®) study, we measured total IgE levels and specific IgE levels to 6 common allergens. Compared to usual chronic obstructive pulmonary disease (COPD), participants with ACO (based on self-report of asthma) had higher total IgE levels (median 67.0 versus 42.2 IU/ml) and more frequently had at least one positive specific IgE (43.5% versus 24.5%). We previously used a strict definition of ACO in participants with COPD, based on self-report of a doctor's diagnosis of asthma before age 40. This strict ACO definition was refined by the presence of atopy, determined by total IgE > 100 IU/ml or at least one positive specific IgE, as was the broader definition of ACO based on self-reported asthma history. Participants with all 3 ACO definitions were younger (mean age 60.0-61.3 years), were more commonly African American (36.8%-44.2%), had a higher exacerbation frequency (1.0-1.2 in the past year), and had more airway wall thickening on quantitative analysis of chest computed tomography (CT) scans. Among participants with ACO, 37%-46% did not have atopy; these individuals had more emphysema on chest CT scan. Based on associations with exacerbations and CT airway disease, IgE did not clearly improve the clinical definition of ACO. However, IgE measurements could be used to subdivide individuals with atopic and non-atopic ACO, who might have different biologic mechanisms and potential treatments.
Bibliographical noteFunding Information:
Abbreviations: asthma-COPD overlap, ACO; immunoglobulin E, IgE; COPD Genetic Epidemiology, COPDGene®; chronic obstructive pulmonary disease, COPD; computed tomography, CT; Global Initiative for Asthma, GINA; Global initiative for chronic Obstructive Lung Disease, GOLD; forced expiratory volume in 1 sec, FEV1; forced vital capacity, FVC; Hounsfield unit, HU; interleukin, IL Funding Support: This study was supported by National Institutes of Health grants R01HL130512, R01HL125583, K23HL123594, P01HL132825, U01HL089856, and U01HL089897 and a grant from Novartis. The COPDGene® study (NCT00608764) is also supported by the COPD Foundation through contributions made to an Industry Advisory Committee comprised of AstraZeneca, Boehringer-Ingelheim, GlaxoSmithKline, Novartis, and Sunovion. Date of Acceptance: October 10, 2019 Citation: Hersh CP, Zacharia S, Prakash R, et al and the COPDGene Investigators. Immunoglobulin E as a biomarker for the overlap of atopic asthma and chronic obstructive pulmonary disease. Chronic Obstr Pulm Dis. 2020;7(1):1-12. doi: https://doi.org/10.15326/ jcopdf.7.1.2019.0138
Dr. Hersh reports grant support from the National Institutes of Health and Novartis for this study. He reports grant support from Boehringer-Ingelheim and personal fees from AstraZeneca and 23andMe outside of this study. None of the other authors report any disclosures related to this study.
- Chest CT scan
- Chronic obstructive pulmonary disease
- Immunoglobulin E