Yoga for asthma: a systematic review and meta-analysis

Background: Although yoga is frequently used by patients with asthma, its efficacy in alleviating asthma remains unclear. Objective: To systematically assess and meta-analyze the available data on efficacy and safety of yoga in alleviating asthma. Methods: MEDLINE/PubMed, Scopus, the Cochrane Central Register of Controlled Trials, PsycINFO, CAM-Quest, CAMbase, and IndMED were searched through January 2014. Randomized controlled trials of yoga for patients with asthma were included if they assessed asthma control, symptoms, quality of life, and/or pulmonary function. For each outcome, standardized mean differences (SMDs) or risk ratios (RRs) and 95% confidence intervals (CIs) were calculated. Risk of bias was assessed using the Cochrane tool. Results: Fourteen randomized controlled trials with 824 patients were included. Evidence for effects of yoga compared with usual care was found for asthma control (RR, 10.64; 95% CI, 1.98 to 57.19; P = .006), asthma symptoms (SMD, -0.37; 95% CI, -0.55 to -0.19; P < .001), quality of life (SMD, 0.86; 95% CI, 0.39 to 1.33; P < .001), peak expiratory flow rate (SMD, 0.49; 95% CI, 0.32 to 0.67; P <.001), and ratio of forced expiratory volume in 1 second to forced vital capacity (SMD, 0.50; 95% CI, 0.24 to 0.75; P < .001); evidence for effects of yoga compared with psychological interventions was found for quality of life (SMD, 0.61; 95% CI, 0.22 to 0.99; P = .002) and peak expiratory flow rate (SMD, 2.87; 95% CI, 0.14 to 5.60; P = .04). No evidence for effects of yoga compared with sham yoga or breathing exercises was revealed. No effect was robust against all potential sources of bias. Yoga was not associated with serious adverse events. Conclusion: Yoga cannot be considered a routine intervention for asthmatic patients at this point. It can be considered an ancillary intervention or an alternative to breathing exercises for asthma patients interested in complementary interventions. (C) 2014 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.