title: Continuous oxygen use in nonhypoxemic emphysema patients identifies a high-risk subset of patients: retrospective analysis of the National Emphysema Treatment Trial.
abstract: BACKGROUND
  Continuous oxygen therapy is not recommended for emphysema patients who are not hypoxemic at rest, although it is often prescribed. Little is known regarding the clinical characteristics and survival of nonhypoxemic emphysema patients using continuous oxygen. Analysis of data from the National Emphysema Treatment Trial (NETT) offers insight into this population.
  
  
  METHODS
  We analyzed demographic and clinical characteristics of 1,215 participants of NETT, stratifying by resting PaO(2) and reported oxygen use. Eight-year survival was evaluated in individuals randomized to medical therapy.
  
  
  RESULTS
  At enrollment, 33.8% (n = 260) of participants nonhypoxemic at rest reported continuous oxygen use. When compared to nonhypoxemic individuals not using oxygen (n = 226), those using continuous oxygen had worse dyspnea, lower quality of life, more frequent exercise desaturation, and higher case-fatality rate. After adjusting for age, body mass index, and FEV(1) percentage of predicted, the presence of exercise desaturation accounted for the differential mortality seen between these groups.
  
  
  CONCLUSIONS
  In the NETT, the use of continuous oxygen in resting nonhypoxemic emphysema patients was associated with worse disease severity and survival. The differential survival observed could nearly all be accounted for by the higher prevalence of exercise desaturation in those using continuous oxygen, suggesting that it is not a harmful effect of oxygen therapy contributing to mortality. It remains unclear whether continuous oxygen therapy improves survival in normoxic patients with exercise desaturation.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD. Electronic address: mdrummo3@jhmi.edu.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Drummond
authors.affiliation: Division of Biostatistics, Department of Oncology, Johns Hopkins University, Baltimore, MD.
authors.forename: Amanda L
authors.initials: AL
authors.lastname: Blackford
authors.affiliation: University of Washington, Seattle, WA.
authors.forename: Joshua O
authors.initials: JO
authors.lastname: Benditt
authors.affiliation: National Jewish Medical Center, Denver, CO.
authors.forename: Barry J
authors.initials: BJ
authors.lastname: Make
authors.affiliation: University of Pittsburgh, Pittsburgh, PA.
authors.forename: Frank C
authors.initials: FC
authors.lastname: Sciurba
authors.affiliation: Division of Pulmonary and Critical Care Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD.
authors.forename: Meredith C
authors.initials: MC
authors.lastname: McCormack
authors.affiliation: University of Michigan, Ann Arbor, MI.
authors.forename: Fernando J
authors.initials: FJ
authors.lastname: Martinez
authors.affiliation: University of Pennsylvania, Philadelphia, PA.
authors.forename: Henry E
authors.initials: HE
authors.lastname: Fessler
authors.affiliation: University of Michigan, Ann Arbor, MI.
authors.forename: Alfred P
authors.initials: AP
authors.lastname: Fishman
authors.affiliation: Division of Pulmonary and Critical Care Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Wise
mesh_terms: D000368:Aged; D004417:Dyspnea / Q000503:physiopathology; D015444:Exercise / Q000502:physiology; D005080:Exercise Test; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010100:Oxygen / Q000627:therapeutic use*; D010102:Oxygen Inhalation Therapy / Q000379:methods*; D011656:Pulmonary Emphysema / Q000401:mortality* / Q000503:physiopathology / Q000628:therapy*; D011788:Quality of Life; D016032:Randomized Controlled Trials as Topic; D012146:Rest / Q000502:physiology; D012189:Retrospective Studies; D012307:Risk Factors; D012720:Severity of Illness Index
chemical_list: D010100:Oxygen