"Yoga could help asthma sufferers, research finds," reports The Independent.
A major review of existing data found there is "moderate-quality evidence" that yoga improves both symptoms and reported quality of life in people with asthma.
Yoga is an ancient form of exercise that focuses on strength, flexibility and breathing to boost physical and mental wellbeing.
Hong Kong-based researchers reviewed previously published data to see if yoga could improve symptoms and quality of life for people with asthma, compared with usual care or a dummy therapy.
Data from 1,048 people who took part in 15 randomised controlled trials (RCTs) was analysed. The researchers found small improvements for quality of life and symptoms, and a reduction in asthma medication use. However, the only meaningful clinical difference was for quality of life.
The review was well designed, but reviews are only as good as the studies they include – there was a high risk of bias in many studies.
There is also no comparison with other forms of exercise that could be equally effective in improving quality of life for people with asthma.
Still, one of the positives of yoga is that, provided you train with a properly qualified instructor, it is relatively risk-free and does not usually have any side effects or complications.
Read more advice about getting started with yoga.
Where did the story come from?
The study was carried out by researchers from the Cochrane Collaboration and was funded by the National Institute for Health Research.
It was published online via the Cochrane Library in the peer-reviewed Cochrane Databases of Systematic Reviews. The Cochrane Library is a non-profit organisation, so, like all their research, the review is open access and can be read for free online.
This story has been reported relatively accurately in the UK media, with a clear message that the findings are not entirely reliable because of the inclusion of flawed studies. We also don't know whether yoga has any negative effects, if any.
However, the Daily Mail's headline that yoga could help people with asthma "get their breath back" and reduce the risk of asthma attacks is rather misleading – this is not what this review concluded.
There was also some inaccuracy with The Independent's story, which incorrectly stated that participants were aged between six months and 23 years old – this was actually how long people had asthma for. We're not sure how you could get a six-month-old baby to start learning yoga.
What kind of research was this?
This systematic review aimed to assess the effect of yoga in people with asthma.
A review like this combines data from individual studies to form conclusions about the current state of the evidence on the effectiveness and safety of an intervention.
Caution should always be taken with the results, however, as a systematic review is only as reliable as the studies included in the analysis.
What did the research involve?
A comprehensive search of medical databases, trial registries, and hand-searching of relevant journals and meeting abstracts was carried out to identify studies for inclusion in the review.
The researchers decided to only include RCTs that compared yoga with usual care, no intervention, or a dummy intervention – a "sham" treatment.
They measured the following outcomes:
- quality of life
- asthma symptom score
- asthma control
- lung function measures
- asthma medication usage
- adverse events
After relevant studies were chosen, data was extracted on the characteristics of participants, interventions, methodology, and outcomes. Outcome data was combined where appropriate and analysed using statistical methods.
What were the basic results?
Fifteen trials were included in the study, with a total of 1,048 participants. Participants mostly had mild to moderate asthma for a range of 6 months to more than 23 years.
The quality of the studies included was assessed as ranging from very low to moderate.
Analysis found some evidence that yoga may improve outcomes in people with asthma compared with usual care or a dummy intervention:
- quality of life – mean score difference on the seven-point scale of the Asthma Quality of Life Questionnaire (AQLQ) 0.57 units (95% confidence interval [CI] 0.37 to 0.77); 0.5 units is considered clinically meaningful
- improve symptoms – standardised mean difference 0.37, 95% CI 0.09 to 0.65; this is equivalent to a small effect
- reduce medication usage – relative risk 5.35, 95% CI 1.29 to 22.11; the wide range of this confidence interval casts the reliability of the result into doubt
To put these findings into context, the change in quality of life had a minimal clinically important difference, while yoga had no clinical benefit for symptoms.
Yoga did not improve lung function during the course of the study and there were no serious side effects associated with the practice, but there was limited data on this outcome.
How did the researchers interpret the results?
The researchers concluded that, "We found moderate-quality evidence that yoga probably leads to small improvements in quality of life and symptoms in people with asthma.
"There is more uncertainty about potential adverse effects of yoga and its impact on lung function and medication usage.
"RCTs with a large sample size and high methodological and reporting quality are needed to confirm the effects of yoga for asthma."
This well-conducted systematic review aimed to assess whether yoga could improve outcomes for people with asthma when compared with usual care or dummy therapy.
Using statistical methods, small improvements were found for quality of life, symptoms, and a reduction in medication use.
However, the only effect that could make a meaningful difference for someone is the small benefit seen for quality of life.
The review itself was well designed. Efforts were made by the researchers to avoid combining studies that differed significantly in their design and methods.
However, this study did have some limitations:
- The studies included were of very low to moderate quality, and many were small in sample size, which has an impact on the reliability of the findings.
- The studies varied widely in their described yoga interventions and additional drug therapy.
- Some of the analyses included small numbers of participants and the confidence intervals were therefore wide, which reduces the reliability of the estimate.
- Data on some outcomes, such as unwanted side effects, was limited.
- Most of the studies included those with mild to moderate asthma, so yoga may not relieve symptoms in those that need it the most.
This review does not produce conclusive evidence that yoga would be beneficial to people with asthma, and any negative effects were not investigated.
The main thing it found was that yoga may improve quality of life – however, this could be the case if you take part in many types of physical activity, not just yoga. There was no comparison with other forms of exercise.
If you have asthma, there is usually no reason why you should have a restricted life. There are several things you can do to keep asthma under control:
- make sure to take all medicine as prescribed
- attend regular reviews
- understand your symptoms – know when to take your inhaler or call for emergency help
- keep away from known triggers, such as animal fur and cigarette smoke
Read more lifestyle advice about how to live better with asthma.
Analysis by Bazian
Edited by NHS Website
Links to the headlines
The Independent, 27 April 2016
Daily Mirror, 27 April 2016
Daily Mail, 27 April 2016
Links to the science
Cochrane Database of Systematic Reviews. Published online April 27 2016