John: Hello, I'm John Hilton, editor of the Cochrane Editorial unit. In many parts of the world, chronic obstructive pulmonary disease (COPD) is the second most common respiratory illness after asthma, and exacerbations and hospitalisations represent a major health burden for patients and healthcare systems. In an updated Cochrane Review from December 2016, Milo Puhan from the University of Zurich in Switzerland and colleagues have examined the latest evidence on the possible role for pulmonary rehabilitation following these exacerbations. Milo tells us what they found in this podcast.

Milo: For patients with stable chronic obstructive pulmonary disease, or COPD, exercise training and other components of pulmonary rehabilitation such as patient education or psychosocial support are an important part of management. More than 50 randomised trials have tested this, and the Cochrane Review shows that pulmonary rehabilitation improves exercise capacity and health-related quality of life for patients.
Leading on from this, we wanted to investigate its effects for patients with unstable COPD, which is experienced during and in the weeks following an exacerbation. The previous version of our Cochrane Review, in 2011, showed that rehabilitation after exacerbation reduces hospital readmissions and mortality and improves health-related quality of life and exercise capacity, informing guidelines that recommend pulmonary rehabilitation. However, some more recent studies have suggested that pulmonary rehabilitation may not always be effective in patients with COPD suffering from an exacerbation and it was important to update the review to bring this evidence within it.
We assessed the effects of pulmonary rehabilitation after COPD exacerbations on hospital admissions as the primary outcome, and on other patient important outcomes such as mortality, health-related quality of life and exercise capacity. This update adds a further 11 randomised trials comparing post-exacerbation rehabilitation and usual care, bringing the total to 20 included studies with nearly 1500 participants with COPD.
The rehabilitation programmes were very different in terms of type and duration of exercise training, patient education and how programmes were organized. For instance, some programmes took place entirely within a pulmonary rehabilitation setting whereas others included patients who started exercise training in hospital before moving on to an outpatient rehabilitation centre and the home setting.
Across the studies, the results for hospital readmissions and mortality were diverse, which might, in part, be due to the variable methodological quality of the studies. 
Some studies found that pulmonary rehabilitation reduced hospital admissions and mortality, while others did not show such effects; and the more extensive rehabilitation programmes seemed to be most effective. We also found high quality evidence for improvements in health-related quality of life and exercise capacity that patients would deem worthwhile. 
In summary, pulmonary rehabilitation is a safe and effective intervention for patients with COPD after they have experienced an exacerbation, but the reasons for diverse effects on hospital readmissions and mortality remain unclear. We’d like to see future research that explores the impact of the extent of the rehabilitation programme and whether its organization within, for example, the rehabilitation setting or in the continuum of care from hospital to home and outpatient care, influences the effects after COPD exacerbations.

John: If you would like to read more about these latest findings and conclusions on the effects of pulmonary rehabilitation after COPD exacerbations, as well as the review Milo mentioned about stable COPD, you can find both online at Cochrane Library dot com with a simple search for ‘pulmonary rehabilitation and COPD’.