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Continuous Oxygen Use in Nonhypoxemic Emphysema Patients Identifies a High-Risk Subset of Patients

Retrospective Analysis of the National Emphysema Treatment Trial

Michael B. Drummond, MD^*; Amanda L. Blackford, ScM; Joshua O. Benditt, MD, FCCP; Barry J. Make, MD, FCCP; Frank C. Sciurba, MD, FCCP; Meredith C. McCormack, MD; Fernando J. Martinez, MD; Henry E. Fessler, MD; Alfred P. Fishman, MD; Robert A. Wise, MD, FCCP; for the NETT Investigators

*From the Division of Pulmonary and Critical Care Medicine (Drs. Drummond, McCormack, Fessler, and Wise), The Johns Hopkins University School of Medicine, Baltimore, MD; Division of Biostatistics (Ms. Blackford), Department of Oncology, Johns Hopkins University, Baltimore, MD; University of Washington (Dr. Benditt), Seattle, WA; National Jewish Medical Center (Dr. Make), Denver, CO; University of Pittsburgh (Dr. Sciurba), Pittsburgh, PA; University of Michigan (Dr. Martinez), Ann Arbor, MI; and University of Pennsylvania (Dr. Fishman), Philadelphia, PA.

Correspondence to: M. Bradley Drummond, MD, The Johns Hopkins University School of Medicine, Division of Pulmonary and Critical Care Medicine, 5501 Hopkins Bayview Circle, JHAAC 4B.70, Baltimore, MD 21224; e-mail: mdrummo3{at}jhmi.edu

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 PaO₂ 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 FEV₁ 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.

Trial registration:Clinicaltrials.gov Identifier: NCT00000606 [ClinicalTrials.gov] .

Key Words: guideline adherence • pulmonary disease • chronic obstructive • supplemental oxygen

Abbreviations: BMI, body mass index • mBODE, modified body mass index, obstruction, dyspnea; exercise capacity • MRC, Medical Research Council Working Party • NETT, National Emphysema Treatment Trial • NOTT, Nocturnal Oxygen Treatment Trial • QWB, quality of well-being score • SGRQ, St. George Respiratory Questionnaire • SpO₂, oxygen saturation by pulse oximetry • UCSD-SOBQ, University of California San Diego Shortness of Breath Questionnaire