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Short-term Effects of Supplemental Oxygen on 6-Min Walk Test Outcomes in Patients With COPD: A Randomized, Placebo-Controlled, Single-blind, Crossover Trial

Submitted by Priscila Robles 

Jarosch I, Gloeckl R, Damm E, Schwedhelm AL, Buhrow D, Jerrentrup A, et al. Short-term Effects of Supplemental Oxygen on 6-Min Walk Test Outcomes in Patients With COPD: A Randomized, Placebo-Controlled, Single-blind, Crossover Trial. Chest. 2017;151(4):795-803.

Providing oxygen supplement (O2_suppl.) to patients with Chronic Obstructive Pulmonary Disease (COPD) who would benefit from this intervention is clinically important.  Identification of those with a high “oxygen response” is also important as there appear to be subgroups with different levels of oxygenation. A total of 124 severe to very severe COPD patients underwent one 6-min walk test on supplemental oxygen, and one 6-min walk test on room air after a practice 6-min walk test in a prospective, randomized, placebo-controlled, single-blind, crossover fashion. Three subgroups were identified through a post-hoc approach: HYX= hypoxemia at rest and following exercise, EIH= exercise-induced hypoxemia; and NOX= normoxemia at rest and during exercise. Results showed significant improvements from O2_suppl. in hypoxemic patients: i) 42% of patients with HYX and 47% with EIH had ≥ 30 metres increase in 6MWD; ii) oxygen saturation (SpO2) improved by 8.5% (HYX) and 5.4% (EIH), and iii) 24% of patients with HYX and 19% with EIH had a reduction in end-exercise dyspnea scores of ≥ 1 Borg point. In normoxemic patients with COPD, oxygen-related effects were not of clinical relevance. O2_suppl. generally improved exercise capacity and oxygenation in COPD patients with HYX as well as EIH; however, final sample size may opaque clinically relevant differences in the characteristic of oxygen responders and nonresponders among those subgroups.

A Randomized Trial of Long-Term Oxygen for COPD with Moderate Desaturation

Submitted by Priscilla Robles

Long-Term Oxygen Treatment Trial Research G, Albert RK, Au DH, Blackford AL, Casaburi R, Cooper JA, Jr., et al. A Randomized Trial of Long-Term Oxygen for COPD with Moderate Desaturation. N Engl J Med. 2016;375(17):1617-27.

The Long-Term Oxygen Treatment Trial (LOTT) is a parallel-group, randomized, multi-centre study of long-term supplemental oxygen in patients with COPD and moderate resting desaturation. The trial was originally designed to test whether the use of supplemental oxygen would result in a longer time to death than no supplemental oxygen among these patients. To meet recruitment goals, the investigators further included patients with exercise-induced desaturation and incorporated the secondary outcome of hospitalization for any cause. Other health outcomes were also assessed. Three hundred and sixty eight patients were assigned to supplemental-oxygen and 370 to no-supplemental-oxygen groups, and were then followed for 1 to 6 years. The prescription of supplemental oxygen (either for resting or exercise-induced desaturation) did not affect the time to death or first hospitalization, time to death, time to first hospitalization, time to first COPD exacerbation, time to first hospitalization for a COPD exacerbation, the rate of all hospitalizations, the rate of all COPD exacerbations, or changes in measures of quality of life, depression, anxiety, or functional status. There was no effect on the primary outcome in subgroups defined according oxygen prescription. The investigators concluded 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.

Clinical Usefulness of Long-Term Oxygen Therapy in Adults

Submitted by Priscilla Robles

Ekstrom M. Clinical Usefulness of Long-Term Oxygen Therapy in Adults. N Engl J Med. 2016;375(17):1683-4.

Whether long-term oxygen therapy is beneficial in moderate hypoxemia is a question no more, according to this NEJM editorial on the Long-Term Oxygen Treatment Trial (LOTT) published in the same issue. The Editorial highlights the lack of quality evidence regarding clinical usefulness of long-term oxygen treatment in patients with COPD and moderate hypoxemia despite frequent prescription, relatively high costs, and the potential burden on patients. The Editor tackles the fact that indication and eligibility criteria have been based on two classic papers that included patients whose characteristics may not adequately reflect characteristics of patients being prescribed such therapy in current practice. Moreover, survival benefit in mild to moderate hypoxemia has not been confirmed in subsequent studies and evidence of efficacy on symptoms and health-related quality of life is also limited. The LOTT study then represents a groundbreaking contribution to the scarce literature on long-term oxygen therapy that includes the largest patient cohort to date, patient-centred outcomes, clinically relevant subgroups with moderate desaturation (at rest and during exercise) and treatment strategies for which evidence is needed. Based on the lack of effect observed in the LOTT, the Editor understands that long-term oxygen therapy should be reserved for those with severe resting hypoxemia to prolong survival, and should not be routinely prescribed for those with mild to moderate hypoxemia.


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