Chronic obstructive pulmonary disease (COPD) is the commonest indication for domiciliary non-invasive ventilation (NIV) in Europe.1 However, there is a paucity of evidence to support its use. A number of short-term randomised controlled trials (RCTs) failed to show any consistent benefit from NIV.2^–5 In a crossover study comparing 3 months of bilevel ventilation plus long term oxygen therapy (LTOT) with LTOT alone,6 there were small improvements in arterial blood gas tensions during spontaneous breathing by day and in health-related quality of life (QOL) with NIV. In a longer term RCT,7 20 patients randomised to NIV were compared with 24 controls; there was a reduction in the need for hospitalisation in the first 3 months in the NIV group but this effect disappeared by 1 year. One-year survival (78%) was similar in both groups. Dyspnoea, measured using the Borg scale, was reduced in the NIV group. In a larger RCT from Italy,8 90 stable patients on oxygen for more than 6 months were randomly assigned to continuing oxygen alone or oxygen and bilevel ventilation. There was no change in survival, lung or inspiratory muscle function, exercise tolerance or sleep quality score in either group. By contrast, the arterial carbon dioxide tension (Paco₂) measured on usual oxygen and resting dyspnoea scores improved. Health-related QOL, as assessed by the Maugeri Foundation Respiratory Failure Questionnaire (MRF 28), improved in the NIV plus oxygen group, but there was no difference in St George’s Respiratory Questionnaire (SGRQ) scores. NIV has also been used as an adjunct to pulmonary rehabilitation with two RCTs showing greater improvements in exercise capacity and QOL when NIV, used overnight, was added to a pulmonary rehabilitation programme.9 10

In this issue of Thorax McEvoy et al11 report the results of an …