FROM THE COCHRANE DATABASE OF SYSTEMATIC REVIEWS

Yoga seems to improve the quality of life and symptoms of people with asthma, suggests a review of 15 randomized controlled trials comprising 1,048 patients with varying degrees of asthma severity.

The studies generally compared the outcomes for asthma patients participating in at least 2 weeks of yoga with the outcomes for those who were treated with usual care for asthma, a sham intervention, or no intervention.

Average improvements in the Asthma Quality of Life Questionnaire scores of 0.57 units per item on a 7-point scale were found through an analysis of responses from 375 individuals, with each person having participated in one of the five randomized controlled trials (RCTs). While the average increase exceeded the minimal clinically important difference (MCID) for this questionnaire, outcomes of two of the trials raise questions about whether the reported improvements in patients’ quality of life can be attributed to yoga. In those two trials, which included a placebo or sham intervention for some of the participants, no differences in these questionnaire scores were found following the interventions.

For 243 asthma patients who participated in three of the RCTs, on average, yoga improved their symptoms by 0.37 standard deviation units of the disease severity scores used.

“Our findings are preliminary and suggestive, rather than conclusive, and therefore should be interpreted cautiously. Yoga probably improves quality of life and symptoms in people with asthma to some extent. However, whether or not the improvements in symptoms exceed the MCID is uncertain due to lack of an established MCID for the severity scores used in the included studies,” noted Zu-Yao Yang of the Chinese University of Hong Kong, and colleagues.

They used various methods to collect data, including searching the Cochrane Airways Group Register of Trials, which is derived from systematic searches of bibliographic databases, and hand-searching respiratory journals and meeting abstracts. They searched all databases from their inception to July 22, 2015, and placed no restriction on language of publication. All studies were parallel-group trials, except for one cross-over trial.

While two of the studies reported adverse events, four of the studies reported having investigated the occurrences of such types of incidents. One of the studies said three participants in its control group required oral steroids because of acute exacerbations of their asthma, but that these adverse events could not be counted as having been caused by yoga. Another study showed that one participant in its yoga group, who used the Pink City Lung Exerciser (a medical device used to mimic the typical patterns of yoga breathing), reported mild dyspnea during the exercise.

“[As] the included studies were mostly small in sample size and at high risk of bias, high-quality RCTs with large sample sizes are needed to confirm the effects of yoga,” the researchers said.

They reported that they had no known declarations of interest. The project was supported by the National Institute for Health Research, via Cochrane Infrastructure funding to the Cochrane Airways Group.

The full review is available in the Cochrane Database of Systematic Reviews ( doi: 10.1002/14651858.CD010346.pub2 ).

klennon@frontlinemedcom.com

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