Ambulatory oxygen improves quality of life of COPD patients: a randomised controlled study

It is unknown whether acute response to ambulatory oxygen (O-2) predicts longer term improvement in health-related quality of life (HRQL) in chronic obstructive pulmonary disease (COPD) patients. The aims of this study were 1) to assess the short-term clinical impact, as determined by HRQL, of ambulatory O-2 in a 12-week, double-blind, randomised crossover study of O-2 (versus cylinder compressed air) of dyspnoeic but not chronically hypoxic COPD patients with exertional desaturation less than or equal to88% (n=41), and 2) to determine whether either baseline characteristics or acute response to O-2 predicts short-term (12 weeks) response. Primary outcome measures were Chronic Respiratory Questionnaire (CRQ), Hospital Anxiety and Depression scale and the short form (SF)-36. Improvements were seen in all domains of the CRQ for cylinder O-2 compared with cylinder air. Significant improvements were also noted in anxiety and depression and in certain domains of the SF-36. There were 28 (68%) acute responders to cylinder O-2 (defined as increase in 6-min walk greater than or equal to 54 in or decrease in post-Borg dyspnoea greater than or equal to 1) and 23 (56%) short-term responders (defined as clinically significant improvement in CRQ). However, acute and short-term responses were not correlated with no predictors of short-term response identified. At study completion, 14 (41%) of acute or short-term responders did not want to continue therapy, with 11 citing poor acceptability or tolerability. Short-term ambulatory oxygen is associated with significant improvements in health-related quality of life. These benefits cannot be predicted by baseline characteristics or acute response. Despite acute or short-term response, a substantial proportion of patients declined ambulatory oxygen.