Novel Respiratory Disability Score Predicts COPD Exacerbations and Mortality in the Spiromics Cohort

• Main Authors: Cooper CB, Paine R, Curtis JL, Kanner RE, Martinez CH, Meldrum CA, Bowler R, O'Neal W, Hoffman EA, Couper D, Quibrera M, Criner G, Dransfield MT, Han MK, Hansel NN, Krishnan JA, Lazarus SC, Peters SP, Barr RG, Martinez FJ, Woodruff PG
• Format: Article
• Language: English
• Published: Dove Medical Press 2020-08-01
• Series: International Journal of COPD
• Subjects: disability; frailty; exacerbation rate; mortality; spiromics
• Online Access: https://www.dovepress.com/novel-respiratory-disability-score-predicts-copd-exacerbations-and-mor-peer-reviewed-article-COPD

Christopher B Cooper,1 Robert Paine,2 Jeffrey L Curtis,3,4 Richard E Kanner,2 Carlos H Martinez,3 Catherine A Meldrum,3 Russell Bowler,5 Wanda O’Neal,6 Eric A Hoffman,7 David Couper,6 Miguel Quibrera,6 Gerald Criner,8 Mark T Dransfield,9 MeiLan K Han,3 Nadia N Hansel,10 Jerry A Krishnan,11 Stephen C Lazarus,12 Stephen P Peters,13 R Graham Barr,14 Fernando J Martinez,15 Prescott G Woodruff12 On behalf of the SPIROMICS investigators1Departments of Medicine and Physiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA; 2Section of Pulmonary and Critical Care Medicine, Department of Veterans Affairs Medical Center, University of Utah, Salt Lake City, UT, USA; 3Pulmonary and Critical Care Medicine Division, Department of Internal Medicine, University of Michigan Health System, Ann Arbor, MI, USA; 4Veterans Affairs Ann Arbor Healthcare System, Ann Arbor, MI, USA; 5National Jewish Health, University of Colorado School of Medicine, Denver, CO, USA; 6University of North Carolina Marisco Lung Institute, Chapel Hill, NC, USA; 7Department of Radiology, University of Iowa, Iowa City, IA, USA; 8Department of Pulmonary and Critical Care Medicine, Temple University, Philadelphia, PA, USA; 9Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA; 10Johns Hopkins University School of Medicine, Baltimore, MD, USA; 11Department of Medicine, University of Illinois at Chicago, Chicago, IL, USA; 12Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of California San Francisco, San Francisco, CA, USA; 13Wake Forest School of Medicine, Winston-Salem, NC, USA; 14Department of Medicine, Columbia University Medical Center, New York, NY, USA; 15Joan and Sanford I Weill Department of Medicine, Division of Pulmonary and Critical Care Medicine, Weill Cornell Medicine, New York, NY, 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 [e-mail]: Some COPD patients develop extreme breathlessness, decreased exercise capacity and poor health status yet respiratory disability is poorly characterized as a distinct phenotype.Objective: To define respiratory disability in COPD based on available functional measures and to determine associations with risk for exacerbations and death.Methods: We analyzed baseline data from a multi-center observational study (SPIROMICS). This analysis includes 2332 participants (472 with severe COPD, 991 with mild/moderate COPD, 726 smokers without airflow obstruction and 143 non-smoking controls).Measurements: We defined respiratory disability by ≥ 4 of 7 criteria: mMRC dyspnea scale ≥ 3; Veterans Specific Activity Questionnaire < 5; 6-minute walking distance < 250 m; St George’s Respiratory Questionnaire activity domain > 60; COPD Assessment Test > 20; fatigue (FACIT-F Trial Outcome Index) < 50; SF-12 < 20.Results: Using these criteria, respiratory disability was identified in 315 (13.5%) participants (52.1% female). Frequencies were severe COPD 34.5%; mild-moderate COPD 11.2%; smokers without obstruction 5.2% and never-smokers 2.1%. Compared with others, participants with disability had more emphysema (13.2 vs. 6.6%) and air-trapping (37.0 vs. 21.6%) on HRCT (P< 0.0001). Using principal components analysis to derive a disability score, two factors explained 71% of variance, and a cut point − 1.0 reliably identified disability. This disability score independently predicted future exacerbations (ß=0.34; CI 0.12, 0.64; P=0.003) and death (HR 2.97; CI 1.54, 5.75; P=0.001). Thus, participants with disability by this criterion had almost three times greater mortality compared to those without disability.Conclusion: Our novel SPIROMICS respiratory disability score in COPD was associated with worse airflow obstruction as well as airway wall thickening, lung parenchymal destruction and certain inflammatory biomarkers. The disability score also proved to be an independent predictor of future exacerbations and death. These findings validate disability as an important phenotype in the spectrum of COPD.Keywords: disability, frailty, exacerbation rate, mortality, SPIROMICS