Determination of whether supplemental oxygen therapy is beneficial during exercise training in patients with COPD: A systematic review and meta-analysis

Exercise training is an integral component of the pulmonary rehabilitation program for patients with chronic obstructive pulmonary disease (COPD). The aim of this study was to systematically search the published literature and analyze the evidence on the efficacy of supplemental oxygen in improving outcomes during exercise training in patients with COPD. The PubMed, Scopus, Cochrane Central Register of Controlled Trials (CENTRAL) and Google scholar databases were searched electronically for articles in the English language published up to May, 2019. In total, 7 trials were included in this systematic review and meta-analysis. There was considerable heterogeneity amongst the included studies. Meta-analysis indicated no significant difference in power (random: MD = -2.38; 95% CI, -5.79 to 1.03; P=0.86) and maximum energy expenditure (VO2 max) (random: MD = -0.01; 95% CI, -0.06 to 0.07; P=0.45) between the oxygen and control groups on maximal exercise testing. Qualitative analysis of the included studies revealed no benefits of supplemental oxygen in improving exercise capacity and dyspnea scores. Data on the quality of life assessed by the Chronic Respiratory Disease Questionnaire was pooled for 95 participants in the study group and 91 participants in the control group. The results indicated no beneficial effects of supplemental oxygen in improving quality of life outcomes (random: MD = -0.09; 95% CI, -0.16 to -0.01; P=0.59). On the whole, the findings of this study indicate that supplemental oxygen during the exercise training of patients with COPD does not improve exercise capacity, dyspnea scores and quality of life. However, the quality of the evidence is weak. Multi-center randomized controlled trials with homogenous methodology and intervention are required to provide stronger evidence on this subject.