Longterm supplemental oxygen had no benefit on multiple outcome measures in patients with stable chronic obstructive pulmonary disease (COPD) and resting or exercise-induced moderate desaturation, Robert Wise, MD, and his colleagues in The Long-Term Oxygen Treatment Trial (LOTT) Research Group reported.
Recommendations that supplemental oxygen be administered to patients with severe desaturation – an oxyhemoglobin saturation of less than 89% on pulse oximetry (SpO2) – date to two trials performed in the 1970s. Since that time, subsequent studies have been performed in patients with COPD and mild-to-moderate daytime hypoxemia, but the studies were underpowered to assess mortality and the impact of oxygen therapy on hospitalization, exercise performance, and quality of life were unclear.
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Dr. Wise, professor of medicine and director of research, in the division of pulmonary and critical care medicine, Johns Hopkins University, Baltimore, and his fellow LOTT researchers examined whether longterm treatment with supplemental oxygen would extend life and avoid hospitalization among patients who had stable COPD with moderate resting desaturation – defined as an SpO2 of 89% to 93% – and patients who had stable COPD with moderate exercise-induced desaturation during the 6-minute walk test – defined as an SpO2 of at least 80% for at least 5 minutes and less than 90% for 10 seconds or more.
The 738 study participants, about 75% of whom were men, were randomly assigned at one of 42 centers either to receive (368) or not to receive (370) longterm supplemental oxygen. In the supplemental oxygen group, patients with resting desaturation were prescribed 24-hour oxygen, and those with desaturation only during exercise were prescribed oxygen during exercise and sleep (N Engl J Med. 2016;375:1617-27. DOI: 10.1056/NEJMoa1604344).
The groups were balanced for oxygen-desaturation type: 60 (16%) and 73 (20%) had oxygen desaturation only at rest, 171 (46%) and 148 (40%) had oxygen desaturation only upon exercise, and 139 (38%) and 147 (40%) had oxygen desaturation at rest and upon exercise. Patients were followed for 1 to 6 years.
Supplemental oxygen, regardless of prescription type or adherence, failed to benefit patients overall or any subgroup of patients with stable COPD and moderate desaturation. The results were similar for all groups based on measures of time to death or first hospitalization (hazard ratio, 0.94; 95% confidence interval [CI], 0.79 to 1.12; P = .52), hospitalization for a COPD-related hospitalizations (rate ratio, 0.99; 95% CI, 0.83 to 1.17), non–COPD-related hospitalizations (rate ratio, 1.03; 95% CI, 0.90 to 1.18), the rate of all hospitalizations (rate ratio, 1.01; 95% CI, 0.91 to 1.13), and the rate of all COPD exacerbations (rate ratio, 1.08; 95% CI, 0.98 to 1.19). Additionally, patients who did and did not receive oxygen treatment did not differ based on changes on measures of quality of life, depression, anxiety, or functional status.
Oxygen treatment also was not without risk. Among the 51 adverse events attributed to the use of supplemental oxygen were 23 reports of tripping over equipment, including two cases that necessitated hospitalization. There were five patients who reported six cases of fires or burns, including one who had to be hospitalized.
The researchers acknowledged that some patients may not have enrolled in the trial because they were too ill or felt that oxygen was beneficial. “Highly symptomatic patients who declined enrollment might have had a different response to oxygen than what we observed in the enrolled patients,” they noted.
Additionally, uniform devices weren’t used for oxygen delivery, so the amount of oxygen delivered may have varied, and the study did not evaluate the immediate effects of oxygen on symptoms or exercise performance. Nocturnal oxygen saturation was not measured, and “some patients with COPD and severe nocturnal desaturation might benefit from nocturnal oxygen supplementation,” they pointed out. Moreover, “patients’ self-reported adherence may have been an overestimate of their actual oxygen use,” they added, noting, however, that there was good agreement with use “as measured by means of serial meter readings on the concentrator.”
Based on the results, the authors concluded, “the consistency of the null findings strengthens the overall conclusion that long-term supplemental oxygen in patients with stable COPD and resting or exercise-induced moderate desaturation has no benefit with regard to the multiple outcomes measured.”
LOTT was funded by the National Heart, Lung, and Blood Institute and the Centers for Medicare and Medicaid Services. LOTT researchers reported relationships with a wide variety of drug companies.
mdales@frontlinemedcom.com
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