CRD summary

The review reported that the Buteyko breathing technique and similar breathing retraining techniques, yoga and respiratory muscle training all showed some benefits as treatments for asthma but there were too few well-designed studies with adequate power and follow-up to allow a definite conclusion to be drawn. This conclusion reflects the evidence presented and seems reliable.

Authors' objectives

To evaluate the effectiveness of breathing retraining techniques (complementary and alternative medicine) in asthma management.

Searching

PubMed, EMBASE, CINAHL and The Cochrane Library were searched from 1954 to 2011. Search terms were reported. Reference lists of retrieved articles were handsearched.

Study selection

Studies that used breathing techniques as a treatment for asthma were included. Asthma had to be diagnosed by a clinician or fulfil the criteria of the American Thoracic Society, British Thoracic Society or those of Crofton and Douglas. Studies had to report spirometry, respiratory resistance, provocation tests, quality-of-life indices, medication use or asthma symptoms as outcomes. Studies that included patients with chronic obstructive pulmonary disease were excluded.

Breathing retraining techniques used were Buteyko breathing technique, yoga, biofeedback and respiratory muscle training. Duration and frequency of the interventions varied. Both children and adults with different stage of asthma were included in the interventions.

Two reviewers were involved in study selection.

Assessment of study quality

Study quality was assessed by randomisation, blinding, sample size, power calculations, duration of training period, run-in and follow-up (where applicable) and baseline comparability.

The authors did not state how many reviewers assessed study quality.

Data extraction

Study characteristics and mean differences were extracted together with their 95% confidence intervals (CI). Study authors were contacted for additional data.

The authors did not state how many reviewers were involved in data extraction.

Methods of synthesis

Pooled weighted mean difference (WMD) and standardised mean difference (SMD), each with 95% CI, were calculated using fixed-effect meta-analysis for continuous outcomes; the random-effects model was used where heterogeneity was observed (Ι²≥25%).

Results of the review

Forty-one studies were included in the review.

Breathing modification technique: There were 12 RCTs and one before-and-after study. Follow-up ranged from one week to 28 weeks. Drop-out rates ranged from zero to 24%. The 12 RCTS (six Buteyko Breathing Technique and six employed respiratory physiotherapy) examined the effect of breathing modification techniques compared with control interventions. Double blinding was effective on four studies and there was a true randomisation in 11 studies.

Meta-analysis showed no significant effect of breathing retraining in peak expiratory flow, forced expiratory volume in one second (FEV1) percentage predictive, FEV1 (litre) and asthma-related quality-of-life score between the two groups. There was a statistically significant effect for end tidal CO₂ from breathing retraining (WMD 1.65 mmHg, 95% CI 0.31 to 2.99; Ι²=41.3%; five trials, 313 participants). The statistical test result was not reported for the before-and-after study.

Yoga: There were nine RCTs and six before-and-after studies. Follow-up times ranged from immediate to 54 months. Drop-out rates ranged from zero to 43%. True randomisation was not clear in six RCTs and double blinding was either not clear or not reported in seven RCTs.

Meta-analysis showed no effect on peak expiratory flow (PEF) or absolute values of FEV1. There was a significant effect of yoga on FEV1 % predicted (WMD 8.79, 95% CI 0.37 to 17.22; heterogeneity present Ι²=65.2%; three trials, 221 participants) and asthma-related quality-of life (SMD -0.61, 95% CI -1.01 to -0.21; Ι²=0%; two trials, 102 participants). Five non-randomised studies reported improvement in lung function, asthma-related quality-of-life or airway hyper-responsiveness for the intervention compared to the control group.

Respiratory muscle training: There were four RCTS. Follow-up times ranged from four months to six months. Drop-out rates ranged from zero to 27%. All studies used muscle strengthening techniques.

Meta-analysis showed significant effect of respiratory training on B2-agonist (WMD -1.19, 95% CI -2.15 to -0.24; Ι²=0%; two trials, 41 participants).

Biofeedback training: There were seven RCTs and five before-and-after studies. Follow-up ranged from zero to 12 months. Drop-out rate ranged from zero to 19%.

Six RCTs and two before-and-after studies found significant improvement in lung function, medication use or asthma symptoms (test results not reported).

Authors' conclusions

The Buteyko breathing technique and similar breathing retraining techniques, yoga and respiratory muscle training all showed some benefits as alternative treatments for asthma. However, there were too few well-designed studies with adequate power and length of follow-up to allow definite conclusions to be drawn.

CRD commentary

The review question and inclusion criteria were clear. Relevant data sources were searched. It was unclear whether language restrictions were applied and there were no apparent searches for unpublished studies so language and publication and language biases could not be ruled out. Appropriate methods to reduce reviewer error and bias were used for the study selection process but it was unclear whether similar methods were used for quality assessment and data extraction. Some criteria were used to assess the quality of the studies but the full results were not reported. Appropriate methods were used to pool data and assess heterogeneity for RCTs.

Given the very small sample sizes, low or some unknown quality of the studies, non-significant results for most of the outcomes and possible language and publication biases, the author’s statement that it was difficult to make a definitive conclusion regarding the benefit of breathing retraining technique seems appropriate.

Implications of the review for practice and research

Practice: The authors stated that on the existing evidence, and provided that prescribed medications were continued, it would be reasonable for clinicians to offer qualified support to asthma patients intending to undertake such techniques under the supervision of a qualified instructor.

Research: The authors stated that further studies of breathing retraining were warranted so that clinicians and patients alike can make informed treatment decisions.

Funding

No funding.

Bibliographic details

Burgess J, Ekanayake B, Lowe A, Dunt D, Thien F, Dharmage SC. Systematic review of the effectiveness of breathing retraining in asthma management. Expert Review of Respiratory Medicine 2011; 5(6): 789-807. [PubMed: 22082165]

Original Paper URL

http://www.expert-reviews.com/doi/abs/10.1586/ers.11.69

Indexing Status

Subject indexing assigned by NLM

MeSH

Adrenal Cortex Hormones /therapeutic use; Adrenergic beta-2 Receptor Agonists /therapeutic use; Anti-Asthmatic Agents /therapeutic use; Anti-Inflammatory Agents /therapeutic use; Asthma /drug therapy /physiopathology /therapy; Biofeedback, Psychology; Breathing Exercises; Bronchodilator Agents /therapeutic use; Combined Modality Therapy; Evidence-Based Medicine; Humans; Lung /drug effects /physiopathology; Randomized Controlled Trials as Topic; Respiratory Muscles /drug effects /physiopathology; Treatment Outcome; Yoga

AccessionNumber

12011007483

Database entry date

27/06/2013

Record Status

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.