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.
Trial registration: ClinicalTrials.gov NCT00000606.