International Journal of COPD (Dec 2019)
Clinical Significance of Bronchodilator Responsiveness Evaluated by Forced Vital Capacity in COPD: SPIROMICS Cohort Analysis
Abstract
Igor Z Barjaktarevic,1 Russell G Buhr,1,2 Xiaoyan Wang,3 Scott Hu,1 David Couper,4 Wayne Anderson,4 Richard E Kanner,5 Robert Paine III,5 Surya P Bhatt,6 Nirav R Bhakta,7 Mehrdad Arjomandi,7 Robert J Kaner,8 Cheryl S Pirozzi,5 Jeffrey L Curtis,9,10 Wanda K O’Neal,4 Prescott G Woodruff,7 MeiLan K Han,9 Fernando J Martinez,8 Nadia Hansel,11 James Michael Wells,6 Victor E Ortega,12 Eric A Hoffman,13 Claire M Doerschuk,4 Victor Kim,14 Mark T Dransfield,6 M Bradley Drummond,4 Russell Bowler,15 Gerard Criner,14 Stephanie A Christenson,7 Bonnie Ronish,5 Stephen P Peters,12 Jerry A Krishnan,16 Donald P Tashkin,1 Christopher B Cooper1 On behalf of the NHLBI SubPopulations and InteRmediate Outcome Measures In COPD Study (SPIROMICS)1Department of Medicine, University of California, Los Angeles, Los Angeles, CA, USA; 2Department of Health Policy and Management, Fielding School of Public Health, University of California, Los Angeles, Los Angeles, CA, USA; 3Department of General Internal Medicine and Health Services Research, University of California, Los Angeles, Los Angeles, CA, USA; 4Department of Medicine, University of North Carolina, Chapel Hill, NC, USA; 5Department of Medicine, University of Utah, Salt Lake City, UT, USA; 6Division of Pulmonary, Allergy and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL, USA; 7Department of Medicine, University of California, San Francisco, San Francisco, CA, USA; 8Department of Medicine, Weill Cornell Weill Cornell Medical Center, New York, NY, USA; 9Department of Medicine, University of Michigan, Ann Arbor, MI, USA; 10Medicine Service, VA Ann Arbor Healthcare System, Ann Arbor, MI, USA; 11Department of Medicine, John Hopkins University, Baltimore, MD, USA; 12Department of Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA; 13Department of Medicine, University of Iowa, Iowa City, IA, USA; 14Department of Thoracic Medicine and Surgery, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA; 15Department of Medicine, National Jewish Health Systems, Denver, CO, USA; 16Department of Medicine, University of Illinois at Chicago, Chicago, IL, USACorrespondence: Christopher B CooperDepartments of Medicine and Physiology, David Geffen School of Medicine, University of California Los Angeles, 10833 Le Conte Avenue, 37-131 CHS, Los Angeles, CA 90095, USAEmail [email protected]: Bronchodilator responsiveness (BDR) is prevalent in COPD, but its clinical implications remain unclear. We explored the significance of BDR, defined by post-bronchodilator change in FEV1 (BDRFEV1) as a measure reflecting the change in flow and in FVC (BDRFVC) reflecting the change in volume.Methods: We analyzed 2974 participants from a multicenter observational study designed to identify varying COPD phenotypes (SPIROMICS). We evaluated the association of BDR with baseline clinical characteristics, rate of prospective exacerbations and mortality using negative binomial regression and Cox proportional hazards models.Results: A majority of COPD participants exhibited BDR (52.7%). BDRFEV1 occurred more often in earlier stages of COPD, while BDRFVC occurred more frequently in more advanced disease. When defined by increases in either FEV1 or FVC, BDR was associated with a self-reported history of asthma, but not with blood eosinophil counts. BDRFVC was more prevalent in subjects with greater emphysema and small airway disease on CT. In a univariate analysis, BDRFVC was associated with increased exacerbations and mortality, although no significance was found in a model adjusted for post-bronchodilator FEV1.Conclusion: With advanced airflow obstruction in COPD, BDRFVC is more prevalent in comparison to BDRFEV1 and correlates with the extent of emphysema and degree of small airway disease. Since these associations appear to be related to the impairment of FEV1, BDRFVC itself does not define a distinct phenotype nor can it be more predictive of outcomes, but it can offer additional insights into the pathophysiologic mechanism in advanced COPD.Clinical trials registration: ClinicalTrials.gov: NCT01969344T4.Keywords: bronchodilator responsiveness, inspiratory capacity, FVC, FEV1, SPIROMICS