EOH Journal Club Seminar - Fall 2018
Date: Thursday September 27, 2018
Time: 11am - 12pm
Presenter: Pattra Chun-on
Paper: Predictors of Asthma/COPD Overlap in FDNY Firefighters With World Trade Center Dust Exposure
Ankura Singh, MPH; Charles Liu, MD; Barbara Putman, MD; Rachel Zeig-Owens, DrPH, MPH; Charles B. Hall, PhD; Theresa Schwartz, MS; Mayris P. Webber, DrPH, MPH; Hillel W. Cohen, DrPH, MPH; Kenneth I. Berger, MD; Anna Nolan, MD; David J. Prezant, MD; and Michael D. Weiden, MD
BACKGROUND: Previously healthy firefighters with World Trade Center (WTC) dust exposure developed airway disease. Risk factors for irritant-associated asthma/COPD overlap are poorly defined.
METHODS: This study included 2,137 WTC-exposed firefighters who underwent a clinically indicated bronchodilator pulmonary function test (BD-PFT) between 9/11/2001 and 9/10/2017.Apost-BD FEV1 increase of>12% and 200 mL from baseline defined asthma, and a post-BD FEV1/FVC ratio < 0.7 identified COPD cases. Participants who met both criteria had asthma/COPD overlap. Eosinophil levels were measured on screening blood tests performed shortly after 9/11/2001 and prior to BD-PFT; a subgroup of participants also had serum IgE and 21 cytokines measured (n ¼215). Marginal Cox regression models formultiple events assessed the associations of eosinophil levels or serum biomarkers with subsequent diagnosis, with age, race, smoking,WTCexposure, first post-9/11 FEV1/FVC ratio, and BMI included as covariates.
RESULTS: BD-PFT diagnosed asthma/COPD overlap in 99 subjects (4.6%), isolated-asthma in 202 (9.5%), and isolated-COPD in 215 (10.1%). Eosinophil concentration $ 300 cells/mL was associated with increased risk of asthma/COPD overlap (hazard ratio [HR], 1.85; 95% CI,1.16-2.95) but not with isolated-asthma or isolated-COPD. Serum IL-4 also predicted asthma/COPD overlap (HR, 1.51 per doubling of cytokine concentration; 95% CI, 1.17-1.95). Greater IL-21 concentration was associated with both isolated-asthma and isolated-COPD (HRs of 1.73 [95% CI, 1.27-2.35] and 2.06 [95% CI, 1.31-3.23], respectively).
CONCLUSIONS: In WTC-exposed firefighters, elevated blood eosinophil and IL-4 levels are associated with subsequent asthma/COPD overlap. Disease-specific T-helper cell type 2 biomarkers present years before diagnosis suggest patient-intrinsic predisposition to irritantassociated asthma/COPD overlap.
KEY WORDS: asthma; airway obstruction; biomarkers; COPD; eosinophils
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