Background: Breathing exercises have been widely used worldwide as a complementary therapy to the pharmacological treatment of people with asthma.
Objectives: To evaluate the evidence for the efficacy of breathing exercises in the management of patients with asthma.
Search methods: The search for trials led review authors to review the literature available in The Cochrane Library, MEDLINE, EMBASE, PsycINFO, CINAHL and AMED and to perform handsearching of respiratory journals and meeting abstracts. Trial registers and reference lists of included articles were also consulted.The literature search has been updated to January 2013.
Selection criteria: We included randomised controlled trials of breathing exercises in adults with asthma compared with a control group receiving asthma education or, alternatively, with no active control group.
Data collection and analysis: Two review authors independently assessed trial quality and extracted data. RevMan software was used for data analysis based on the fixed-effect model. Continuous outcomes were expressed as mean differences (MDs) with confidence intervals (CIs) of 95%. Heterogeneity was assessed by inspecting the forest plots. The Chi(2) test was applied, with a P value of 0.10 indicating statistical significance. The I(2) statistic was implemented, with a value greater than 50% representing a substantial level of heterogeneity.
Main results: A total of 13 studies involving 906 participants are included in the review. The trials were different from one another in terms of type of breathing exercise performed, number of participants enrolled, number and duration of sessions completed, outcomes reported and statistical presentation of data. Asthma severity in participants from the included studies ranged from mild to moderate, and the samples consisted solely of outpatients. The following outcomes were measured: quality of life, asthma symptoms, number of acute exacerbations and lung function. Eleven studies compared breathing exercise with inactive control, and two with asthma education control groups. All eight studies that assessed quality of life reported an improvement in this outcome. An improvement in the number of acute exacerbations was observed by the only study that assessed this outcome. Six of seven included studies showed significant differences favouring breathing exercises for asthma symptoms. Effects on lung function were more variable, with no difference reported in five of the eleven studies that assessed this outcome, while the other six showed a significant difference for this outcome, which favoured breathing exercises. As a result of substantial heterogeneity among the studies, meta-analysis was possible only for asthma symptoms and changes in the Asthma Quality of Life Questionnaire (AQLQ). Each meta-analysis included only two studies and showed a significant difference favouring breathing exercises (MD -3.22, 95% CI -6.31 to -0.13 for asthma symptoms; MD 0.79, 95% CI 0.50 to 1.08 for change in AQLQ). Assessment of risk of bias was impaired by incomplete reporting of methodological aspects of most of the included trials.
Authors' conclusions: Even though individual trials reported positive effects of breathing exercises, no reliable conclusions could be drawn concerning the use of breathing exercises for asthma in clinical practice. This was a result of methodological differences among the included studies and poor reporting of methodological aspects in most of the included studies. However, trends for improvement are encouraging, and further studies including full descriptions of treatment methods and outcome measurements are required.