Continuous oxygen use in nonhypoxemic emphysema patients identifies a high-risk subset of patients: retrospective analysis of the National Emphysema Treatment Trial.
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.
Drummond
Michael B
MB
Division of Pulmonary and Critical Care Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD. Electronic address: mdrummo3@jhmi.edu.
Blackford
Amanda L
AL
Division of Biostatistics, Department of Oncology, Johns Hopkins University, Baltimore, MD.
Benditt
Joshua O
JO
University of Washington, Seattle, WA.
Make
Barry J
BJ
National Jewish Medical Center, Denver, CO.
Sciurba
Frank C
FC
University of Pittsburgh, Pittsburgh, PA.
McCormack
Meredith C
MC
Division of Pulmonary and Critical Care Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD.
Martinez
Fernando J
FJ
University of Michigan, Ann Arbor, MI.
Fessler
Henry E
HE
University of Pennsylvania, Philadelphia, PA.
Fishman
Alfred P
AP
University of Michigan, Ann Arbor, MI.
Wise
Robert A
RA
Division of Pulmonary and Critical Care Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD.
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
D010100:Oxygen