title: Clinical, physiologic, and radiographic factors contributing to development of hypoxemia in moderate to severe COPD: a cohort study.
abstract: Hypoxemia is a major complication of COPD and is a strong predictor of mortality. We previously identified independent risk factors for the presence of resting hypoxemia in the COPDGene cohort. However, little is known about characteristics that predict onset of resting hypoxemia in patients who are normoxic at baseline. We hypothesized that a combination of clinical, physiologic, and radiographic characteristics would predict development of resting hypoxemia after 5-years of follow-up in participants with moderate to severe COPD METHODS: We analyzed 678 participants with moderate-to-severe COPD recruited into the COPDGene cohort who completed baseline and 5-year follow-up visits and who were normoxic by pulse oximetry at baseline. Development of resting hypoxemia was defined as an oxygen saturation ≤88% on ambient air at rest during follow-up. Demographic and clinical characteristics, lung function, and radiographic indices were analyzed with logistic regression models to identify predictors of the development of hypoxemia.
  
  
  
  Forty-six participants (7%) developed resting hypoxemia at follow-up. Enrollment at Denver (OR 8.30, 95%CI 3.05-22.6), lower baseline oxygen saturation (OR 0.70, 95%CI 0.58-0.85), self-reported heart failure (OR 6.92, 95%CI 1.56-30.6), pulmonary artery (PA) enlargement on computed tomography (OR 2.81, 95%CI 1.17-6.74), and prior severe COPD exacerbation (OR 3.31, 95%CI 1.38-7.90) were independently associated with development of resting hypoxemia. Participants who developed hypoxemia had greater decline in 6-min walk distance and greater 5-year decline in quality of life compared to those who remained normoxic at follow-up.
  
  
  
  Development of clinically significant hypoxemia over a 5-year span is associated with comorbid heart failure, PA enlargement and severe COPD exacerbation. Further studies are needed to determine if treatments targeting these factors can prevent new onset hypoxemia.
  
  
  
  COPDGene is registered at ClinicalTrials.gov: NCT00608764 (Registration Date: January 28, 2008).
authors.affiliation: Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama Birmingham, Birmingham, AL, USA. jmwells@uabmc.edu.|Lung Health Center University of Alabama Birmingham, Birmingham, AL, USA. jmwells@uabmc.edu.|Birmingham VA Medical Center, Birmingham, AL, USA. jmwells@uabmc.edu.|, 1900 University Blvd, THT 422, Birmingham, AL, 35294, USA. jmwells@uabmc.edu.
authors.forename: J Michael
authors.initials: JM
authors.lastname: Wells
authors.affiliation: Department of Radiology, Brigham and Women's Hospital, Boston, MA, USA.
authors.forename: Raul San Jose
authors.initials: RS
authors.lastname: Estepar
authors.affiliation: Channing Division of Network Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Merry-Lynn N
authors.initials: MN
authors.lastname: McDonald
authors.affiliation: Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama Birmingham, Birmingham, AL, USA.|Lung Health Center University of Alabama Birmingham, Birmingham, AL, USA.
authors.forename: Surya P
authors.initials: SP
authors.lastname: Bhatt
authors.affiliation: Division of Pulmonary Medicine, Brigham and Women's Hospital, Boston, MA, USA.
authors.forename: Alejandro A
authors.initials: AA
authors.lastname: Diaz
authors.affiliation: Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama Birmingham, Birmingham, AL, USA.|Lung Health Center University of Alabama Birmingham, Birmingham, AL, USA.
authors.forename: William C
authors.initials: WC
authors.lastname: Bailey
authors.affiliation: Department of Radiology, Brigham and Women's Hospital, Boston, MA, USA.
authors.forename: Francine L
authors.initials: FL
authors.lastname: Jacobson
authors.affiliation: Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama Birmingham, Birmingham, AL, USA.|Lung Health Center University of Alabama Birmingham, Birmingham, AL, USA.|Birmingham VA Medical Center, Birmingham, AL, USA.
authors.forename: Mark T
authors.initials: MT
authors.lastname: Dransfield
authors.affiliation: Division of Pulmonary Medicine, Brigham and Women's Hospital, Boston, MA, USA.
authors.forename: George R
authors.initials: GR
authors.lastname: Washko
authors.affiliation: Division of Pulmonary, Critical Care, and Sleep Medicine, National Jewish Health, Denver, CO, USA.
authors.forename: Barry J
authors.initials: BJ
authors.lastname: Make
authors.affiliation: Rehabilitation Clinical Trials Center, Los Angeles Biomedical Research Institute at Harbor UCLA Medical Center, Torrance, CA, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Casaburi
authors.affiliation: Department of Radiology, University of Edinburgh, Edinburgh, Scotland, UK.
authors.forename: Edwin J R
authors.initials: EJ
authors.lastname: van Beek
authors.affiliation: Department of Radiology, University of Iowa, Iowa City, IA, USA.
authors.forename: Eric A
authors.initials: EA
authors.lastname: Hoffman
authors.affiliation: Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: Frank C
authors.initials: FC
authors.lastname: Sciurba
authors.affiliation: Division of Pulmonary, Critical Care, and Sleep Medicine, National Jewish Health, Denver, CO, USA.
authors.forename: James D
authors.initials: JD
authors.lastname: Crapo
authors.affiliation: Channing Division of Network Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Edwin K
authors.initials: EK
authors.lastname: Silverman
authors.affiliation: Channing Division of Network Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Craig P
authors.initials: CP
authors.lastname: Hersh
mesh_terms: D000368:Aged; D015897:Comorbidity; D003430:Cross-Sectional Studies; D018450:Disease Progression; D005260:Female; D006333:Heart Failure / Q000453:epidemiology*; D006801:Humans; D000860:Hypoxia / Q000453:epidemiology*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010092:Oximetry; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications* / Q000503:physiopathology*; D011788:Quality of Life; D012146:Rest; D012307:Risk Factors; D012720:Severity of Illness Index; D014057:Tomography, X-Ray Computed; D014481:United States; D000070857:Walk Test