Long term oxygen does not benefit patients with stable COPD, study finds

Prescribing long term oxygen to patients with stable chronic obstructive pulmonary disease (COPD) and moderate desaturation at rest or during exercise does not extend the time to death or first admission or improve lung function or exercise capacity, a randomised trial has shown.1

Previous studies have shown that long term supplemental oxygen may reduce mortality in patients with COPD and severe resting hypoxaemia, resulting in guidelines recommending supplemental oxygen for patients with an oxyhaemoglobin saturation of less than 89%. But the benefits of long term oxygen in COPD patients with mild to moderate hypoxaemia have not been clear.

The Long-Term Oxygen Treatment Trial set out to investigate supplemental oxygen in patients with COPD and moderate resting desaturation, but lower than expected mortality prompted researchers to expand the trial to include patients with exercise induced desaturation. They randomly assigned 738 patients to long term supplemental oxygen or to a control group given no oxygen and followed them up for one to six years.

Results, published in the New England Journal of Medicine, showed no significant difference between patients given long term oxygen and those who were not in the composite endpoint of death or first admission for any cause (34.2 per 100 person years with oxygen v 36.4 per 100 person years without oxygen; hazard ratio 0.94 (95% confidence interval 0.79 to 1.12); P=0.52).

The study also found no difference between the two groups in the rate of COPD exacerbations (rate ratio 1.08 (0.98 to 1.19)) or COPD related admissions (0.99 (0.83 to 1.17)). And it found no consistent differences in measures of quality of life, lung function, or the distance patients could walk in six minutes.

“Among patients with stable COPD and resting or exercise induced moderate desaturation, we found that long term supplemental oxygen did not provide any benefit with respect to the time of death or first hospitalisation or any sustained benefit with respect to any other measured outcome,” said the research group, led by Robert Wise, of Johns Hopkins Asthma and Allergy Center in Baltimore, USA.

Magnus Ekström, of Lund University in Sweden, commented in an accompanying editorial, “Long term oxygen therapy should not be routinely prescribed in patients with mild or moderate hypoxemia at rest or during exercise.”2

He recommended that long term oxygen should be prescribed to prolong survival only in patients with COPD who have chronic severe resting hypoxaemia. Ekström proposed that patients with moderate exertional hypoxaemia and intractable breathlessness despite appropriate therapy should be given blinded exercise tests while breathing ambient air or oxygen and that long term oxygen therapy should be continued only in patients who show benefit.

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