No link between long-term oxygen, improved mortality for stable COPD

Use of long-term supplemental oxygen did not prolong life or delay time to first hospitalization compared with no long-term supplementation in patients with stable chronic obstructive pulmonary disease (COPD) with resting or exercise-induced moderate desaturation, according to the results of a study published in The New England Journal of Medicine.

“COPD patients with moderate resting oxygen desaturation or who have desaturation only with exercise do not benefit [from supplemental oxygen] in terms of survival or hospitalization,” study researcher Robert Wise, MD, of the Johns Hopkins Asthma and Allergy Center in Baltimore, Maryland, told Medical Economics. “However, prior evidence supports the fact that COPD patients with more severe resting oxygen desaturation do have improved survival.”

The efficacy of long-term supplemental oxygen in patients with stable COPD and resting or exercise-induced moderate desaturation was unknown. According to Wise, currently, most physicians do not provide oxygen to patients with COPD with moderate resting desaturation. However, it is very common that patients who had moderate exercise-induced desaturation receive supplemental oxygen with activity and sleep.

Next: Study details

In this study, Wise and colleagues evaluated whether supplemental oxygen would result in longer time to death compared with no use of supplemental oxygen. The study was originally designed to test this in patients with stable COPD with moderate resting desaturation (oxyhemoglobin saturation as measured by pulse oximetry [Spo₂ ], 89% to 93%); however, after seven months the trial was redesigned to include patients with stable COPD with moderate exercise-induced desaturation (during the six-minute walk test, Spo₂ ≥80% for ≥5 minutes and <90% for ≥10 seconds). In addition, the researchers added the endpoint of time to first hospitalization for any cause.

The study included 738 patients who were randomly assigned to receive long-term supplemental oxygen or no long-term supplemental oxygen. Patients with resting desaturation were prescribed 24-hour oxygen; those with exercise-induced desaturation were prescribed oxygen during exercise and sleep. Patients were followed for between one and six years.

There was no significant difference between those patients who received supplemental oxygen and those who did not for the time to death or first hospitalization (hazard ratio [HR]=0.94; 95% CI, 0.79-1.12; P=0.52). Additionally, there was no difference in the rates of all hospitalizations (rate ratio [RR]=1.01), COPD exacerbations (RR=1.08), and COPD-related hospitalizations (RR=0.99).

“We did a number of subgroup analyses and several subgroups such as those who had recent severe exacerbations seemed to do better, but the results were not statistically conclusive,” Wise said.

Those patients assigned to supplemental oxygen who had a COPD exacerbation 1 to 3 months prior to enrollment had a longer time to death or first hospitalization than those in the no oxygen group (HR=0.58; 95% CI, 0.39-0.88; P=0.007). Longer time to death or first hospitalization was also observed for patients who were 71 years of age or older at enrollment (HR=0.75; 95% CI, 0.57-0.99; P=0.03) and those who had a lower quality of life score at enrollment (HR=0.77; 95% CI, 0.60-0.99; P=0.03).

However, after adjustment for multiple comparisons, none of these subgroup-by-treatment interactions effects remained statistically significant.

“Our recommendations based on the study is that patients who are using oxygen for moderate resting or exercise-induced desaturation should discuss this with their physicians,” Wise said. “Our study provides evidence that can be integrated into this conversation and individual decision-making.”

For example, if the use of long-term supplemental oxygen helps improve symptoms and activity level it is reasonable to continue using it, Wise said. If it does not provide symptomatic benefit, then the choice of whether or not to use oxygen should be considered in the context of the finding that it does not improve life expectancy or reduce hospitalizations.