Asthma is a chronic condition affecting the lungs, characterized by a reversible airflow limitation and symptoms such as wheezing, chest tightness, cough, and dyspnoea. Airflow limitation is a consequence of chronic inflammation, respiratory wall thickening, and rise in mucous production. Epidemiologic studies show that this condition affects about 300 million people worldwide, and it was responsible for 420,000 deaths in 2016. Asthma severity varies individually, and people who experience severe symptoms have a diminished quality of life and an increased risk of hospitalization and death. Some of the people with asthma may have a clinical overlap with chronic obstructive pulmonary disease (COPD), with an incompletely reversible airflow obstruction on spirometry, history of exacerbation, and severe functional impairment. In this scenario, rehabilitation aims to educate and improve the physical and psychological state of these patients, and modern programmes favour at least four weeks of structured training, even at high intensity, although few patients are eventually able to achieve that. Components of pulmonary rehabilitation (PR) programmes and their mode of delivery are not agreed upon. Pulmonary rehabilitation is proven to be beneficial in many respiratory conditions, and many biological effects were studied on COPD; therefore, PR is not univocally recommended for people with asthma, and there is a need for clearer evidence.
This review investigated whether, compared to usual care, pulmonary rehabilitation was able to improve exercise performance, asthma control, strength, physical activity levels, and quality of life, and whether it was helpful to reduce inflammatory biomarkers exacerbations/hospitalisations and adverse events.
This review is important for
People with asthma and dyspnoea, their loved ones/caregivers, health professionals caring for this population, general practitioners, researchers, and policymakers.
Outcomes of this review
This is an update of Cochrane Systematic Reviews (CSRs) published in 2007 and 2017. The outcomes analysed were exercise performance, asthma control, quality of life, number of exacerbations/hospitalisations, mental health, strength, levels of physical activity, inflammatory biomarkers, and adverse events.
The CSR included 10 studies published and/or registered up to May 2021 with 894 participants. Results showed that, compared to usual care, pulmonary rehabilitation probably increases physical fitness immediately after completion of the programme, but it may make little to no difference one year later. Pulmonary rehabilitation may make little or no difference on asthma control immediately after completion of the programme or up to one year later compared to usual care. Pulmonary rehabilitation probably improves quality of life as assessed by the St George’s Respiratory Disease questionnaire immediately after intervention, but because this result may differ according to the type of assessment tool used, it is uncertain whether this effect lasts one year.
There was insufficient data available for meta-analysis to determine the effect of pulmonary rehabilitation on rates of asthma exacerbations/hospitalisations, mental health, strength, levels of physical activity, or markers of inflammation.
These results must be interpreted with caution because of (i) the small sample sizes of all the included studies, and (ii) inconsistencies between studies for patient inclusion, type of exercise and overall programme duration, evaluation instruments, and time for reassessment. (iii) People with asthma may have different abilities to perform pulmonary
rehabilitation, especially because of exercise-induced bronchoconstriction limiting performance intensity and, thus, affecting outcomes. (iv) This review found evidence in favour of shorter programmes for milder disease, although this may result from the weighted impact of a single larger study. (v) Only one study evaluated the weight of asthma-COPD overlap on outcomes, thus limiting the capacity of the review to assess this issue. (vi) As previously stated, there was little data for most of secondary
outcomes; therefore, meta-analysis was not possible for any of these outcomes.
Author’s conclusion of the review
Pulmonary rehabilitation is likely to be helpful for people with asthma to improve exercise capacity and quality of life at the end of the intervention. However, it is difficult to assess the precise magnitude of effect and its clinical relevance because the certainty of evidence was very low to low. Pulmonary rehabilitation may make little or no difference on asthma control, as the certainty of evidence is very low to low.
There was insufficient data to assess the role of the intervention on level of physical activity, inflammatory biomarkers, mental health, and adverse events. Findings from one study suggest close monitoring for exercise-induced bronchoconstriction in patients completing maximal incremental treadmill tests.
Unclear reporting, small sample size, and study heterogeneity determine inconsistency of the findings, thus limiting applicability of the results.
The authors recommended that large-scale, multi-centre studies are needed, particularly to (a) support the results of this review for pulmonary rehabilitation on exercise tolerance and asthma control. (b) Further research should enquire about inflammatory biomarkers, muscle strength, level of physical activity, and mental health. (c) Further efforts should also define the type and time of interventions to decrease their heterogeneity. (d) The authors also suggest that the point of view of the patient can be implemented designing future trials with qualitative research methodology, such as qualitative enquiry and principles of co-design. This could benefit pulmonary rehabilitation programmes including behavioural change and exercise. (e) They should also involve careful consideration of important clinical features, such as patient age and asthma severity. (f) Studies should also address the definition of some important asthma phenotypes, such as people with obesity and asthma-COPD overlap, which may benefit from specific types of multimodal interventions. (g) Further enquiry is indicated to determine whether the different types of physical inactivity present in COPD and asthma may result in different responses to pulmonary rehabilitation.
Robin Kuruvila Sentinella