No effect of nocturnal oxygen on survival, progression to long-term oxygen therapy in COPD

The INOX trial failed to show an effect of nocturnal oxygen on survival or progression to long-term oxygen therapy in patients with chronic obstructive pulmonary disease, according to data published in The New England Journal of Medicine.

“Sleep-related nonapneic oxygen desaturation often occurs in patients with COPD not qualifying for long-term oxygen therapy,” Yves Lacasse, MD, from the University Institute of Cardiology and Respirology of Quebec, and colleagues wrote. “This phenomenon is considered by many physicians as an indication for prescribing nocturnal oxygen because the progression of COPD to its end stages of severe hypoxemia, right heart failure and death may result from the severity of desaturation occurring during sleep.”

Nocturnal oxygen desaturation in patients with COPD causes systemic inflammation that may contribute to pathogenesis of pulmonary hypertension and cardiovascular diseases, according to the researchers.

The double-blind, placebo-controlled, randomized INOX trial enrolled 243 patients with COPD with nocturnal arterial oxygen desaturation who did not qualify for long-term oxygen therapy. Patients also had an oxygen saturation of < 90% for at least 30% of the time on nocturnal oximetry. All patients were randomly assigned to receive nocturnal oxygen (n = 123) or ambient air from a sham concentrator (placebo; n = 120).

The primary outcome was death from any cause or requirement for long-term oxygen therapy, which was defined by the Nocturnal Oxygen Therapy Trial criteria. Secondary outcomes included rates of exacerbation and hospitalization.

Patient recruitment in the INOX trial was halted early due to difficulties with recruitment and retention.

Of those randomly assigned to nocturnal oxygen, 39% met the criteria for long-term oxygen therapy or had died at 3-year follow-up compared with 42% of patients in the placebo group (difference, –3%; 95% CI, –15.1 to 9.1).

Researchers observed no significant differences between groups in rates of COPD exacerbation and hospitalization.

“Our trial did not show evidence of an effect of nocturnal oxygen therapy on survival or progression to long-term oxygen therapy in patients with COPD with isolated nocturnal oxygen desaturation,” the researchers wrote. “Because enrollment in the trial was stopped before we had reached our proposed sample size, the trial was underpowered with the consequences of a wide confidence interval around the point estimate of the absolute difference in risk between the trial groups at 3 years of follow-up.”