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Review
, 11 (11), CD006429

Oxygen for Breathlessness in Patients With Chronic Obstructive Pulmonary Disease Who Do Not Qualify for Home Oxygen Therapy

Affiliations
Review

Oxygen for Breathlessness in Patients With Chronic Obstructive Pulmonary Disease Who Do Not Qualify for Home Oxygen Therapy

Magnus Ekström et al. Cochrane Database Syst Rev.

Abstract

Background: Breathlessness is a cardinal symptom of chronic obstructive pulmonary disease (COPD). Long-term oxygen therapy (LTOT) is given to improve survival time in people with COPD and severe chronic hypoxaemia at rest. The efficacy of oxygen therapy for breathlessness and health-related quality of life (HRQOL) in people with COPD and mild or no hypoxaemia who do not meet the criteria for LTOT has not been established.

Objectives: To determine the efficacy of oxygen versus air in mildly hypoxaemic or non-hypoxaemic patients with COPD in terms of (1) breathlessness; (2) HRQOL; (3) patient preference whether to continue therapy; and (4) oxygen-related adverse events.

Search methods: We searched the Cochrane Airways Group Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and Embase, to 12 July 2016, for randomised controlled trials (RCTs). We handsearched the reference lists of included articles.

Selection criteria: We included RCTs of the effects of non-invasive oxygen versus air on breathlessness, HRQOL or patient preference to continue therapy among people with COPD and mild or no hypoxaemia (partial pressure of oxygen (PaO2) > 7.3 kPa) who were not already receiving LTOT. Two review authors independently assessed articles for inclusion in the review.

Data collection and analysis: Two review authors independently collected and analysed data. We assessed risk of bias by using the Cochrane 'Risk of bias tool'. We pooled effects recorded on different scales as standardised mean differences (SMDs) with 95% confidence intervals (CIs) using random-effects models. Lower SMDs indicated decreased breathlessness and reduced HRQOL. We performed subanalyses and sensitivity analyses and assessed the quality of evidence according to the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) approach.

Main results: Compared with the previous review, which was published in 2011, we included 14 additional studies (493 participants), excluded one study and included data for meta-analysis of HRQOL. In total, we included in this review 44 studies including 1195 participants, and we included 33 of these (901 participants)in the meta-analysis.We found that breathlessness during exercise or daily activities was reduced by oxygen compared with air (32 studies; 865 participants; SMD -0.34, 95% CI -0.48 to -0.21; I2 = 37%; low-quality evidence). This translates to a decrease in breathlessness of about 0.7 points on a 0 to 10 numerical rating scale. In contrast, we found no effect of short-burst oxygen given before exercise (four studies; 90 participants; SMD 0.01, 95% CI -0.26 to 0.28; I2 = 0%; low-quality evidence). Oxygen reduced breathlessness measured during exercise tests (25 studies; 442 participants; SMD -0.34, 95% CI -0.46 to -0.22; I2 = 29%; moderate-quality evidence), whereas evidence of an effect on breathlessness measured in daily life was limited (two studies; 274 participants; SMD -0.13, 95% CI, -0.37 to 0.11; I2 = 0%; low-quality evidence).Oxygen did not clearly affect HRQOL (five studies; 267 participants; SMD 0.10, 95% CI -0.06 to 0.26; I2 = 0%; low-quality evidence). Patient preference and adverse events could not be analysed owing to insufficient data.

Authors' conclusions: We are moderately confident that oxygen can relieve breathlessness when given during exercise to mildly hypoxaemic and non-hypoxaemic people with chronic obstructive pulmonary disease who would not otherwise qualify for home oxygen therapy. Most evidence pertains to acute effects during exercise tests, and no evidence indicates that oxygen decreases breathlessness in the daily life setting. Findings show that oxygen does not affect health-related quality of life.

Conflict of interest statement

ME, ZA, ABH and DC declare no conflicts of interest relevant to this work.

AA is the Chief Medical Officer and Chief Scientific Officer at Flatiron Health, a cancer‐focused health technology company in New York, New York, USA. Collaborators and end‐users of the dataset and Flatiron's research & analytics services include academic researchers, pharmaceutical manufacturers and government users, including the US FDA. Investors in Flatiron include three pharmaceutical manufacturers (Roche, Amgen, Celgene), but these venture investments do not relate to any drug products. These companies have no specific data rights and no say in the day‐to‐day research activities at Flatiron.

Figures

Figure 1
Figure 1
Study flow diagram.
Figure 2
Figure 2
Methodological quality summary: review authors' judgements about each methodological quality item for each included study.
Figure 3
Figure 3
Funnel plot of comparison: 1 Oxygen versus air, outcome: 1.1 Breathlessness ‐ all trials.
Figure 4
Figure 4
Forest plot of comparison: 1 Oxygen versus air, outcome: 1.2 Breathlessness ‐ subgroup analysis ‐ short‐burst oxygen versus not.
Figure 5
Figure 5
Forest plot of comparison: 1 Oxygen versus air, outcome: 1.5 Breathlessness ‐ subgroup analysis ‐ measured during exercise test versus not.
Figure 6
Figure 6
Forest plot of comparison: 1 Oxygen versus air, outcome: 1.13 Health‐related quality of life ‐ all trials.
Analysis 1.1
Analysis 1.1
Comparison 1 Oxygen versus air, Outcome 1 Breathlessness ‐ all trials.
Analysis 1.2
Analysis 1.2
Comparison 1 Oxygen versus air, Outcome 2 Breathlessness ‐ subgroup analysis ‐ short‐burst oxygen vs not.
Analysis 1.3
Analysis 1.3
Comparison 1 Oxygen versus air, Outcome 3 Breathlessness ‐ subgroup analysis ‐ exertional desaturation vs not.
Analysis 1.4
Analysis 1.4
Comparison 1 Oxygen versus air, Outcome 4 Breathlessness ‐ subgroup analysis ‐ mean PaO2 < 9.3 kPa vs higher.
Analysis 1.5
Analysis 1.5
Comparison 1 Oxygen versus air, Outcome 5 Breathlessness ‐ subgroup analysis ‐ measured during exercise test vs not.
Analysis 1.6
Analysis 1.6
Comparison 1 Oxygen versus air, Outcome 6 Breathlessness ‐ subgroup analysis ‐ laboratory vs other.
Analysis 1.7
Analysis 1.7
Comparison 1 Oxygen versus air, Outcome 7 Breathlessness ‐ subgroup analysis ‐ short‐term vs long‐term (training) effect of oxygen.
Analysis 1.8
Analysis 1.8
Comparison 1 Oxygen versus air, Outcome 8 Breathlessness ‐ subgroup analysis ‐ mean oxygen dose > 2 L/min vs lower.
Analysis 1.9
Analysis 1.9
Comparison 1 Oxygen versus air, Outcome 9 Breathlessness ‐ sensitivity analysis ‐ excluding measurements at peak exertion.
Analysis 1.10
Analysis 1.10
Comparison 1 Oxygen versus air, Outcome 10 Breathlessness ‐ sensitivity analysis ‐ excluding studies with high risk of bias.
Analysis 1.11
Analysis 1.11
Comparison 1 Oxygen versus air, Outcome 11 Breathlessness ‐ sensitivity analysis ‐ excluding outliers.
Analysis 1.12
Analysis 1.12
Comparison 1 Oxygen versus air, Outcome 12 Breathlessness ‐ sensitivity analysis ‐ post hoc ‐ excluding short‐burst and outliers.
Analysis 1.13
Analysis 1.13
Comparison 1 Oxygen versus air, Outcome 13 Health‐related quality of life ‐ all trials.

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