Breathing exercises for adults with asthma

  • Conclusions changed
  • Review
  • Intervention

Authors


Abstract

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 Chi2 test was applied, with a P value of 0.10 indicating statistical significance. The I2 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.

Résumé scientifique

Exercices de respiration chez les adultes asthmatiques

Contexte

Les exercices de respiration sont largement utilisés dans le monde en tant que traitement complémentaire pour le traitement pharmacologique de personnes souffrant d'asthme.

Objectifs

Évaluer les preuves concernant l'efficacité des exercices de respiration dans la prise en charge des patients asthmatiques.

Stratégie de recherche documentaire

Les auteurs de la revue ont recherché des essais dans La Bibliothèque Cochrane, MEDLINE, EMBASE, PsycINFO, CINAHL et AMED et réalisé une recherche manuelle dans des journaux sur la respiration et dans des résumés de conférences. Les registres des essais et les références bibliographiques des articles inclus ont également été consultés.

La recherche de littérature a été mise à jour jusqu'en janvier 2013.

Critères de sélection

Nous avons inclus les essais contrôlés randomisés portant sur des exercices de respiration chez les adultes atteints d'asthme par rapport à un groupe témoin recevant une formation en matière d'asthme ou à un groupe témoin avec un contrôle inactif.

Recueil et analyse des données

Deux auteurs de la revue ont indépendamment évalué la qualité des essais et extrait les données de manière indépendante. Le logiciel RevMan a été utilisé pour l'analyse des données sur la base du modèle à effets fixes. Les critères de jugement étaient exprimés sous forme de différences moyennes (DM) avec des intervalles de confiance (IC) de 95 %. L'hétérogénéité a été évaluée en inspectant les espaces forestiers. Le test Chi2 a été appliqué, avec une valeur P de 0,10, indiquant une signification statistique. La statistique I2 a été utilisée, avec une valeur supérieure à 50 % représentant un niveau d'hétérogénéité substantiel.

Résultats principaux

Treize études portant sur 906 participants ont été inclues dans la revue. Les essais étaient différents les uns des autres en termes de type d'exercices de respiration réalisés, du nombre de participants recrutés, du nombre et de la durée des séances, des critères indiqués et de la présentation statistique des données. La gravité de l'asthme chez les participants des études incluses variait de légère à modérée et les échantillons étaient uniquement des patients non hospitalisés. Les critères de jugement suivants ont été mesurés : La qualité de vie, les symptômes de l'asthme, le nombre d'exacerbations aiguës et la fonction pulmonaire. Onze études ont comparé des exercices de respiration avec un contrôle inactif et deux groupes témoins avec une formation en matière d'asthme. Les huit études ayant évalué la qualité de vie ont rapporté une amélioration dans ce domaine. Une amélioration dans le nombre d'exacerbations aiguës a été observée par la seule étude ayant évalué ce critère. Six des sept études incluses montraient des différences significatives en faveur des exercices de respiration pour les symptômes de l'asthme. Les effets sur la fonction pulmonaire étaient plus variable, aucune différence n'a été rapportée dans cinq des onze études ayant évalué ce critère, tandis que les six autres études qui favorisaient les exercices de respiration ont montré une différence significative. En raison de l'hétérogénéité substantielle entre les études, une méta-analyse a été possible uniquement pour les symptômes de l'asthme et le questionnaire sur la qualité de vie des asthmatiques (AQLQ). Chaque méta-analyse incluait seulement deux études et a montré une différence significative en faveur des exercices de respiration (DM de -3,22, IC à 95 % -6,31 à -0,13 pour les symptômes de l'asthme ; DM de 0,79, IC à 95 % 0,50 à 1,08 à changer en AQLQ). Le risque de biais était limité par la consignation incomplète des aspects méthodologiques de la plupart des essais inclus.

Conclusions des auteurs

Bien que des essais individuels aient rapporté des effets positifs concernant les exercices de respiration, aucune conclusion fiable n'a pu être tirée concernant l'utilisation des exercices de respiration pour le traitement de l'asthme dans la pratique clinique. Il s'agissait d'un résultat de différences méthodologiques entre les études incluses et la notification médiocre des aspects méthodologiques dans la plupart des études incluses. Cependant, les tendances pour l'amélioration sont encourageantes et d'autres études décrivant les méthodes de traitement et les mesures de critères de jugement sont nécessaires.

Plain language summary

Breathing exercises for asthma

Background

Asthma is a lung disease, that comprises underlying inflammation and tightening of the small tubes in the airways (called airway obstruction), which occurs in response to asthma triggers such as animal danders or pollen (also called bronchial hyperresponsiveness). The high prevalence of asthma worldwide is a major public health problem because of the high healthcare costs associated with hospitalisation and medication. Breathing exercises are a non-pharmacological intervention that has been used routinely in the treatment of patients with asthma. Breathing exercises aim to control the hyperventilation symptoms of asthma and can be performed as the Papworth Method, the Buteyko breathing technique, yoga or any other similar intervention that manipulates the breathing pattern.

Review question

We wanted to look at available evidence for the effectiveness of breathing exercises in adults with asthma.

Key results

We found 13 studies involving 906 adults with mild to moderate asthma. Eleven studies compared breathing exercises with inactive controls and two with asthma education control groups. Overall, improvements in quality of life, asthma symptoms and numbers of exacerbations were reported. Six of the eleven studies that assessed lung function showed a significant difference favouring breathing exercises. No adverse effects related to the intervention were described, which indicates that this is a safe and well-tolerated intervention in people with asthma.

Quality of the evidence

The trials were different in terms of type of breathing exercises performed, number of participants enrolled, number and duration of sessions completed, outcomes reported and statistical presentation of data. As a result, we were not able to compare the results from these trials using a meta-analysis for all outcomes. Meta-analysis was possible for only two outcomes (asthma symptoms and change in Asthma Quality of Life Questionnaire—AQLQ), each of which was reported in only two studies. Both meta-analyses showed a significant difference favouring breathing exercises. The methods used to conduct these studies were not as well reported as we would have liked, and so the quality of the trials was unclear. Overall the quality of the evidence included in the review was very low.

Conclusion

Even though individual trials reported positive effects of breathing exercises, no conclusive evidence in this review supports or refutes the efficacy of such intervention in the treatment of adult patients with asthma.

Résumé simplifié

Exercices de respiration pour le traitement de l'asthme

Contexte

L'asthme est une maladie pulmonaire, caractérisé par une inflammation sous-jacente et un resserrement de petits tubes dans les voies respiratoires (appelé obstruction des voies respiratoires). Les crises d'asthme sont déclenchées par les phanères d’animaux ou le pollen (également appelées hyperréactivité bronchique). La forte prévalence de l'asthme dans le monde est un problème de santé publique majeur dû aux importants coûts de soins de santé associés à une hospitalisation et des médicaments. Les exercices de respiration sont des interventions non pharmacologiques qui ont été systématiquement utilisés dans le traitement des patients asthmatiques. Les exercices de respiration visent à contrôler les symptômes d'hyperventilation et peuvent être réalisés par la Méthode Papworth, la technique de respiration Buteyko, le yoga ou toute autre intervention similaire qui manipule le profil respiratoire.

Question de la revue

Nous avons cherché à examiner les preuves disponibles pour l'efficacité des exercices de respiration chez les adultes asthmatiques.

Résultats principaux

Nous avons trouvé 13 études portant sur 906 adultes atteints d'asthme léger à modéré. Onze études comparaient les exercices de respiration avec un contrôle inactif et deux études composées de groupes témoins ayant reçu un programme d’éducation sur l’asthme. Les améliorations de la qualité de vie, les symptômes de l'asthme et le nombre d'exacerbations ont été rapportés. Six des onze études qui évaluaient la fonction pulmonaire ont montré une différence significative en faveur des exercices de respiration. Aucun effet indésirable lié à l'intervention n’a été mentionné, ce qui indique qu'il s'agit d'une intervention sûre et bien tolérée chez les personnes asthmatiques.

Qualité des preuves

Les essais étaient différents en termes de type d'exercices de respiration réalisés, du nombre de participants recrutés, du nombre et de la durée des séances, des critères indiqués et de la présentation statistique des données. En conséquence, nous n'avons pas été en mesure de comparer tous les critères de jugement de ces essais en utilisant une méta-analyse. La méta-analyse n'a été possible que pour deux critères de jugement (les symptômes de l'asthme et le questionnaire sur la qualité de vie des asthmatiques (AQLQ - Asthma Quality of Life Questionnaire), chacun de ces critères de jugement était rapporté dans seulement deux études. Les deux méta-analyses ont montré une différence significative en faveur des exercices de respiration. Nous aurions souhaitez que les méthodes soient mieux documentées, la qualité des essais n'était donc pas claire. La qualité globale des preuves inclues dans cette revue était très faible.

Conclusion

Bien que des essais individuels aient rapporté des effets positifs grâce aux exercices de respiration, aucune preuve concluante dans cette revue soutient ou récuse clairement l'efficacité d'une telle intervention dans le traitement des patients adultes asthmatiques.

Notes de traduction

Traduit par: French Cochrane Centre 14th January, 2014
Traduction financée par: Ministère du Travail, de l'Emploi et de la Santé Français

Ringkasan bahasa mudah

Latihan pernafasan untuk asma

Latar Belakang

Asma merupakan sejenis penyakit paru-paru yang terdiri daripada radang paru-paru serta pengetatan tiub-tiub pernafasan kecil dalam salur pernafasan (dikenali sebagai penghalangan saluran pernafasan), yang berlaku akibat tindakbalas badan terhadap pencetus asma seperti bulu haiwan dan debunga (juga dikenali sebagai tindak balas bronkial). Kelaziman asma yang tinggi di seluruh dunia merupakan satu masalah kesihatan awam yang utama disebabkan oleh kos perubatan rawatan yang tinggi termasuklah kos kemasukan wad dan ubat-ubatan. Latihan pernafasan merupakan satu intervensi bukan farmakologi yang telah digunakan secara rutin dalam rawatan pesakit asma.Latihan pernafasan bertujuan untuk mengawal gejala-gejala hiperventilasi asma serta boleh dilakukan melalui beberapa kaedah seperti Kaedah Papworth, teknik pernafasan Buteyko, yoga atau intervensi yang lain yang dapat memanipulasi corak pernafasan.

Soalan kajian

Kami hendak melihat kepada bukti yang sedia ada tentang keberkesanan latihan pernafasan di kalangan orang dewasa yang menghidap penyakit asma.

Hasil utama

Kami menemui 13 kajian yang melibatkan 906 orang dewasa yang mempunyai asma bertahap ringan sehingga sederhana. Sejumlah 11 kajian telah membandingkan latihan pernafasan dengan kumpulan kawalan yang tidak aktif, serta juga dengan kumpulan kawalan pendidikan asma. Keseluruhannya, terdapat peningkatan kualiti hidup, gejala-gelaja asma dan jumlah serangan asma telah dilaporkan. Enam daripada 11 kajian yang menilai fungsi paru-paru telah menunjukkan perbezaan yang ketara yang memihak kepada latihan pernafasan. Tiada kesan buruk berkaitan dengan intervensi yang telah diterangkan, yang menunjukkan bahawa intervensi ini selamat dan baik diterima oleh mereka yang menghidap penyakit asma.

Kualiti bukti

Kajian percubaan yang terlibat adalah berbeza dari segi jenis latihan pernafasan yang dilakukan, jumlah peserta yang terlibat, jumlah dan tempoh masa sesi-sesi yang selesai, hasil yang dilaporkan serta perbentangan statistik data. Oleh sebab itu, kami tidak dapat membandingkan keputusan dalam ujian-ujian ini dengan menggunakan meta-analisis untuk kesemua hasil pendapatan. Meta-analisis hanya dapat dijalankan bagi dua hasil keputusan (gejala-gejala asma dan perubahan dalam Asthma Quality of Life Questionnaire-AQLQ), yang dilaporkan dalam dua kajian. Kedua-dua keputusan meta-analysis menunjukkan perbezaan yang ketara yang memihak kepada latihan pernafasan. Kaedah yang digunakan dalam menjalani kajian-kajian ini tidak dilaporkan sebaik yang kami jangka. Oleh yang demikian, kualiti kajian-kajian ini tidak dijelaskan. Keseluruhannya, kualiti bukti-bukti yang terlibat dalam ulasan ini adalah amat rendah.

Kesimpulan

Walaupun kajian-kajian individu telah melaporkan kebaikan latihan pernafasan, tiada bukti yang kukuh di dalam ulasan ini yang menyokong atau melawan keberkesanan intervensi seperti ini di dalam rawatan pesakit asma di kalangan orang dewasa.

Catatan terjemahan

Diterjemahkan oleh Yap Kar Suan (Melaka Manipal Medical College). Disunting oleh Gan Siew Hua (Universiti Sains Malaysia). Untuk sebarang pertanyaan sila hubungi yapkarsuan@gmail.com.

எளியமொழிச் சுருக்கம்

ஆஸ்துமாக்கான சுவாசப் பயிற்சிகள்

பின்புலம்

ஆஸ்துமா நுரையீரலை பாதிக்கும் நோய், இதில் விலங்குகளில் இருந்து உதிரும் முடி,இறகு மற்றும் தோல் (danders) அல்லது மகரந்தம் போன்ற ஆஸ்துமா தூண்டிகளால் (இதனை மூச்சுக்குழாய் ஹைப்பர்ரெஸ்பான்சிவ்னஸை என அழைப்பர்) காற்று செல்லும் பாதையிலுள்ள சிறிய மூச்சுக்குழாய்களில் அழற்சி மற்றும் இறுக்கம் உண்டாகும். (சுவாசப்பாதையில் அடைப்பு என அழைக்கப்படும்). மருத்துவமனையில் சேர்ப்பது மற்றும் அதனால் ஏற்படும் செலவுகள் (அனுமதிக்கப்பட்ட செலவு மற்றும் மருந்தின் செலவு) காரணமாக உலகளவில் பரவலாக மக்களை பாதிக்கும் ஆஸ்துமா ஒரு பெரிய உடல்நல பிரச்னையாக உருவாகி உள்ளது. சுவாசப் பயிற்சிகள் ஒரு மருந்தற்ற சிகிச்சையாக உள்ள தலையீடாகும். இது ஆஸ்துமா உள்ளவர்களுக்கு வழக்கமான சிகிச்சையாக பயன்படுத்தப்படுகின்றது.சுவாசப் பயிற்சிகள், ஆஸ்துமா அறிகுறிகளான மிகை காற்றோட்டத்தை (அதிகமூச்சு) கட்டுப்படுத்துவதை நோக்கமாக கொண்டுள்ளன. இது பாப்வொர்த் செயல்முறை, புடிகோ சுவாச நுட்பம், யோகா அல்லது சுவாச அமைமுறையை மாற்றுவதின் மேல் நோக்கம் கொண்ட அதே மாதிரியான பிற செயல்முறைகளிலும் செயலாக்கப்படுகிறது.

திறனாய்வு கேள்வி

ஆஸ்துமா உள்ள பெரியவர்களுக்கு சுவாசப் பயிற்சிகளின் வினைவுறுதிறன் குறித்து கிடைக்கக் கூடிய ஆதாரங்களை காண நாங்கள் விரும்பினோம்.

முக்கிய முடிவுகள்

லேசான முதல் மிதமான ஆஸ்துமா கொண்ட 906 பெரியவர்களை உள்ளடக்கிய 13 ஆய்வுகளை நாங்கள் கண்டறிந்தோம். பதினொரு ஆய்வுகள் சுவாசப் பயிற்சியினை செயலற்று கட்டுப்பாட்டுகுழுக்களுடனும் இரண்டு ஆய்வுகள்ஆஸ்துமா பற்றின கல்வி கட்டுப்பாட்டு குழுக்களுடனும் செயல்படுத்தி ஒப்பிட்டன. ஒட்டுமொத்தமாக, வாழ்க்கை தரம், ஆஸ்துமா அறிகுறிகள் மற்றும் நோய் பண்பு மிகத்தல் போன்ற நிகழ்வுகளின் எண்ணிக்கை மேம்பட்டது. நுரையீரல் செயல்பாட்டு திறனை மதிப்பீடு செய்த 11 ஆய்வுகளில் 6ஆய்வுகள், சுவாசப் பயிற்சி செய்தவர்களுக்கு சாதகமாக குறிப்பிடத்தக்க வேறுபாடு உள்ளது என்று தெரிவித்தன. இந்த சிகிச்சை எந்தவிதமான பக்க விளைவுகளையும் ஏற்படுத்தியதாக தெரிவிக்கப் படவில்லை. இது இந்த சிகிச்சை பாதுகாப்பானது மற்றும் ஆஸ்துமா உள்ளவர்கள் பொறுத்துக்கொள்ளகூடியது என்பதைக் காண்பிக்கிறது.

ஆதாரங்களின் தரம்

சுவாசப் பயிற்சி முறைகள், ஆய்வில் சேர்த்துக் கொள்ளப்பட்ட பங்கேற்பாளர்களின் எண்ணிக்கை, சிகிச்சைகளின் எண்ணிக்கை மற்றும் சிகிச்சை காலஅளவு, ஆய்வில் அறிவிக்கப்பட்ட விளைவுபயன் அளவீடு மற்றும் தரவு புள்ளிவிவர வழங்கல் போன்றவை இந்த ஆய்வுகளில் விதவிதமாக இருந்தன. இதன் விளைவாக, மெட்டா-பகுப்பாய்வு மூலமாக (ஒருங்கிணைத்தல்) இந்த சோதனைகளின் முடிவுகளை எங்களால் ஒப்பிட முடியவில்லை. இரு விளைவுகளுக்கு மட்டுமே (ஆஸ்துமா அறிகுறிகள் மற்றும் ஆஸ்துமா வாழ்க்கை தரம் கேள்விப்பட்டியல்— AQLQ) மெட்டா-பகுப்பாய்வு செய்யமுடிந்தது.இவை ஒவ்வொன்றும் இரண்டு ஆய்வுகளில்மட்டும் அறிவிக்கப்பட்டது. இந்த இரண்டு மெட்டா-பகுப்பாய்வுகளும், குறிப்பிடத்தக்க வேறுபாடு உள்ளது என்று சுவாசப் பயிற்சி செய்தவர்களுக்கு சாதகமாக தெரிவித்தன. ஆய்வுகளை நடத்துவதற்கு பயன்படுத்தப்பட்ட செயல்முறைகள், நாம் விரும்புகிற வண்ணம் சிறப்பாக அறிக்கையிடப்படவில்லை. அதனால் சோதனைகளின் தரத்தை பற்றியும் தெளிவு இல்லை. ஒட்டுமொத்தமாக திறனாய்வுக்கு சேர்க்கப்பட்டுள்ள ஆதாரங்களின் தரம் மிகவும் குறைவாக இருந்தது.

முடிவுரை

ஆஸ்துமா உள்ள பெரியவர்களுக்கு (adults) சுவாசப் பயிற்சிகள் சாதகமான விளைவுகளை ஏற்படுத்தும் என்று சிலதனிப்பட்ட ஆய்வுகள் கூறியபோதும் இதன் பலாபலனை ஆதரிக்கவோ அல்லது ஆட்சேபிக்கவோ, முடிவான ஆதாரங்கள் இந்த திறனாய்வில் இல்லை.

மொழிபெயர்ப்பு குறிப்புகள்

மொழிபெயர்ப்பாளர்: சி.இ.பி.என்.ஆர் குழு

Summary of findings(Explanation)

Summary of findings for the main comparison. 
  1. a(-1 limitations) Methods of randomisation and allocation concealment and any attempts to blind outcome assessors were not described in one study assessing this outcome.

    b(-1 limitations) One study with a high risk of bias for 'blinding of outcome assessment' due to lack of blinding.

    cSingle study.

    d(-1 limitations) Methods of randomisation and allocation concealment and any attempts to blind outcome assessors were not described in the studies assessing this outcome.

    eSubstantial heterogeneity (I2 = 82%).

Breathing exercises compared with inactive control for asthma

Patient or population: adults with asthma

Settings: outpatient

Intervention: breathing exercises

Comparison: inactive control

OutcomesIllustrative comparative risks* (95% CI)Relative effect
(95% CI)
No of participants
(studies)
Quality of the evidence
(GRADE)
Comments
Assumed riskCorresponding risk
Inactive controlBreathing exercises

Change in AQLQ

Follow-up: 8 weeks to 3 months

Mean AQLQ score ranged across control groups from 0.14 to 4.5Mean AQLQ score in the intervention groups was 0.79 higher
(0.50 to 1.08 higher)
MD 0.79 (0.50 to 1.08)172 (2 studies)⊕⊝⊝⊝
very lowa
I2 = 43%

Change in SGRQ

Follow-up: 6 and 12 months

See commentSee comment

Not

estimable

78 at 6 months post baseline (1 study)

72 at 12 months post baseline (1 study)

⊕⊝⊝⊝

very lowb,c

Only one trial contributed to this outcome, so we were unable to pool data

Asthma symptoms

Measured by the Nijmegen questionnaire

Follow-up: 6 months to 12 months

Mean asthma symptoms ranged across control groups from 15 to 16.4Mean asthma symptoms in the intervention groups was 3.22 lower
(6.31 to 0.13 lower)
MD -3.22 (-6.31 to -0.13)118 (2 studies)⊕⊝⊝⊝
very lowb
I2 = 0%

Number of acute exacerbations

Number of attacks recorded by a diary

Follow-up: 6 to 54 months

See commentSee comment

Not

estimable

106 (1 study)⊕⊝⊝⊝
very lowd
Only one trial contributed to this outcome, so we were unable to pool data
Inpatient hospitalisation episodesSee commentSee commentSee commentSee commentSee commentNo studies reported this outcome

Lung function (FEV1)

Percentage of predicted

Follow-up: 8 weeks

Mean FEV1 ranged across control groups from 59.9% to 77.26%See comment

Not

estimable

177 (2 studies)⊕⊝⊝⊝
very lowd,e
We were unable to pool data for this outcome because of substantial heterogeneity
Days off workSee commentSee commentSee commentSee commentSee commentNo studies reported this outcome
*The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).
AQLQ: Asthma Quality of Life Questionnaire; CI: Confidence interval; FEV1: forced expiratory volume in 1 second; SGRQ: St George’s Respiratory Questionnaire.

Background

Description of the condition

Asthma is a chronic inflammatory disorder of the lungs that can lead to structural and functional changes, resulting in bronchial hyperresponsiveness and airflow obstruction (Taylor 2008; Holgate 2009; Zhang 2010; Allen 2012; Brightling 2012). Symptoms of asthma include recurrent episodes of wheeze, cough, breathlessness and chest tightness, together with episodes of marked worsening of symptoms, known as exacerbations (Bateman 2008; Zhang 2010; Brightling 2012).

The diagnosis of asthma is based on the individual's medical history, physical examination findings and lung function and laboratory test results (Sveum 2012). Measurement of lung function provides an assessment of the severity of airflow limitation. These measures yield complementary information about different aspects of asthma control and are obtained by spirometry and by peak expiratory flow measurement (GINA 2011). Assessment of airway responsiveness to factors that can cause asthma symptoms, evaluation of airway inflammation and measurement of allergic status may facilitate the diagnosis of patients with asthma (GINA 2011).

Asthma is a serious public health problem that is a major cause of disability and health resource utilisation for those affected (Bateman 2008; Eisner 2012; To 2012). Around 300 million individuals of all ages worldwide are affected by asthma (Bateman 2008; Bousquet 2010; Brightling 2012). Increases in morbidity, mortality and economic costs are associated with severe or difficult to treat asthma, particularly in industrialised countries (Zhang 2010; Eisner 2012).

Asthma has been associated with symptomatic hyperventilation, which decreases carbon dioxide (CO2) levels, causing hypocapnia (Thomas 2001; Laffey 2002; Bruton 2005a). Hypocapnia resulting from hyperventilation may perpetuate the bronchospasm and culminate in a cycle of progressive hypocapnia and increasing bronchospasm (Laffey 2002). Thus, hypocapnia may contribute to increased airway resistance in patients with asthma (van den Elshout 1991; Laffey 2002). This fact has led to increasing interest in strategies that can be used to reduce hyperventilation. In addition, psychological symptoms may interfere with the severity of the respiratory symptoms and may influence patients’ quality of life (Rimington 2001; Juniper 2004). Thus, an important component of asthma management is identifying individual issues that impair health-related quality of life and treating them (Rimington 2001; Juniper 2004).

Description of the intervention

Although no cure for asthma is known, its symptoms are controllable in most patients (Taylor 2008). Asthma treatment can be pharmacological or non-pharmacological or a combination of the two associated with strategies of symptom control (environmental triggers and asthma education) (Wolf 2008; Burgess 2011; GINA 2011; Welsh 2011).

Medications to treat asthma can be broadly divided into long-term controllers and short-term relievers (Arun 2012). Controller medications are taken daily on a long-term basis, and the relievers are used to rapidly decrease bronchoconstriction and relieve its symptoms (GINA 2011). Such treatment can be administered in different ways (by inhalation, orally or parenterally) (GINA 2011).  

Non-pharmacological interventions have gained attention in the treatment of asthma. Complementary and alternative medicine includes breathing exercises, homeopathy, acupuncture, aromatherapy, reflexology, massage, inspiratory muscle training and the Alexander technique (Blanc 2001; Ram 2009; Dennis 2012; McCarney 2012). Breathing exercises have been used routinely by physiotherapists and other professionals to control the hyperventilation symptoms of asthma (Bruton 2005b) and can be performed as the Papworth method, Buteyko breathing technique, yoga or any other similar intervention that manipulates the breathing pattern (Ram 2003). 

How the intervention might work

Work undertaken at the Papworth Hospital, in Cambridge, UK, has changed the techniques used for treatment of asthma and hyperventilation (Cluff 1984; Innocenti 1993; Holloway 1994; Lum 1994). The Papworth method focuses on the use of an appropriate breathing pattern to reduce hyperventilation and hyperinflation, therefore increasing CO2 levels and thus reducing the effects of hypocapnia and some symptoms attributed to asthma crisis.

The Buteyko method was developed in the 1950s by Konstantin Buteyko; the rationale behind its use is similar to that of the Papworth method for people who experience hypocapnia as a major contributor to their asthma symptoms. This method aims to develop a more efficient pattern of respiration through the use of controlled breathing and respiratory pauses. As a result, the method intends to increase alveolar and arterial CO2 tension, which may reverse bronchospasm, normalise the breathing pattern and reduce breathlessness (Bruton 2005b; Burgess 2011).

Yoga is an ancient discipline from India that has been shown to be an alternative technique for the management of asthma to help reduce anxiety associated with asthma symptoms. Some mechanisms may explain the rationale for yoga, such as reduction in psychological overactivity and emotional instability, and thereby reduction in efferent vagal discharge; increased autonomic control; decreased vagal outflow to the lung causing bronchodilatation and decreased bronchial reactivity (Singh 1990a). Yoga breathing techniques include deep breathing exercises (pranayama), which deal explicitly with control of breathing, postures (asanas), cleansing techniques (kriyas), meditation, prayer and often dietary changes to reduce asthma symptoms (Burgess 2011).

Why it is important to do this review

The worldwide high prevalence of asthma has become a public health problem because of the high healthcare costs resulting from hospitalisation and medication (Giavina-Bianchi 2010).

Breathing exercises have been used widely as an adjunct therapy in the treatment of asthmatic patients, generating considerable interest among researchers to develop studies that seek to show evidence of the effectiveness of this intervention.

This is an update of a review last published in 2003, in which the review authors concluded that there was insufficient evidence on the clinical benefits of breathing exercises in patients with asthma. Recently, new studies have been conducted to evaluate the effects of breathing exercises on quality of life, symptom control and lung function in asthmatic patients. Thus, within this review update, we aim to summarise and assess evidence from randomised controlled trials showing the efficacy of breathing exercises in the treatment of patients with asthma.  

Objectives

To evaluate the evidence for the efficacy of breathing exercises in the management of patients with asthma.

Methods

Criteria for considering studies for this review

Types of studies

Randomised controlled trials of breathing exercises in adults with asthma.

Types of participants

Adult patients with physician diagnosed asthma and/or diagnosis by internationally established criteria: American Thoracic Society (ATS), European Respiratory Society (ERS) or British Thoracic Society (BTS). Patients may be either community or hospital based with their treatment supervised by a general practitioner or respiratory specialist.

Types of interventions

Intervention: Patients with asthma who have received at least one course of treatment comprising breathing retraining.

Comparison: Control group receiving asthma education or, alternatively, no active control group (e.g. waiting list control).

Types of outcome measures

Primary outcomes
  • Quality of life.

Secondary outcomes
  • Asthma symptoms (e.g. measures of dyspnoea or breathlessness with Borg score or visual analogue scale).

  • Number of acute exacerbations (mean number and number of participants experiencing one or more exacerbations).

  • Inpatient hospitalisation episodes.

  • Physiological measures—lung function (especially low flow rates) and functional capacity.

  • General practitioner (GP) or hospital outpatient appointments or both.

  • Days off work.

  • Patient's subjective evaluation of the intervention.

Search methods for identification of studies

Electronic searches

Trials were identified from the Cochrane Airways Group Specialised Register of Trials (CAGR), which is derived from systematic searches of bibliographic databases including the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, CINAHL, AMED and PsycINFO, and from handsearching of respiratory journals and meeting abstracts (see Appendix 1 for further details). All records in the CAGR coded as 'asthma' were searched using the following terms:

((breath*) and (technique* or exercise* or re-train* or train* or re-educat* or educat* or physiotherap* or "physical therap*" or "respiratory therapy")) or (buteyko or "qigong yangsheng" or pranayama* OR yoga*) or "breathing control"

For the previous version of this review, searches were conducted up to April 2003. For this version, the literature search has been updated to February 2012. A repeat search was undertaken in January 2013.

Searching other resources

Reference lists of relevant articles found by the above methods were consulted to look for additional studies, and a search in clinical trial registries (clinicaltrials.gov and the WHO trial portal) was undertaken to look for planned, ongoing and unpublished trials.

Data collection and analysis

Selection of studies

Two review authors (DAF and GSSC) independently assessed studies for the possibility of inclusion in this review. We retrieved full text articles and reviewed them to determine eligibility. Final decisions and disagreements were resolved by consultation with a third review author (KMPPM).

Data extraction and management

Two review authors (DAF and GSSC) independently extracted data into RevMan (RevMan 2011) by using a standard data collection form. According to methods described in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011a), we collected information from the studies, including the following.

  • Methods (design, method of randomisation, method of allocation concealment, outcome assessor blinding, withdrawal and dropouts).

  • Participants (country, health status, mean age, gender, total sample and exclusion criteria).

  • Interventions (methods and types of intervention, including number and duration of sessions and methods used for control group comparisons).

  • Outcomes (improvement in quality of life indices, asthma symptoms, number of acute exacerbations, inpatient hospitalisation episodes, etc).

We resolved disagreements by discussion and consensus.

Assessment of risk of bias in included studies

Two review authors (DAF and GSSC) independently assessed the risk of bias using The Cochrane Collaboration’s tool for assessing risk of bias, which includes the following items: random sequence generation, allocation concealment, blinding of participants and personnel, blinding of outcome assessment, incomplete outcome data, selective reporting and other sources of bias. The risk of bias was classified as high, low or unclear, according to the methods described in Chapter 8 of the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011b). Disagreements were resolved by discussion and consensus.

Measures of treatment effect

Continuous outcomes were expressed as mean difference (MD) with 95% confidence interval (CI) when outcome measurements were performed on the same scale, or as standardised mean difference (SMD) with 95% CI when studies assessed an outcome by using different methods.

Unit of analysis issues

Trials with a cross-over and cluster-randomised design were not included in the review.

Dealing with missing data

We wrote to authors of included trials to request additional data as required.

Assessment of heterogeneity

We assessed heterogeneity by inspecting the forest plots to detect non-overlapping CIs, while applying the Chi2 test with a P value of 0.10 indicating statistical significance. We also implemented the I2 statistic, with a value of 50% denoting moderate levels of heterogeneity and above 50% indicating a substantial level of heterogeneity (Higgins 2011c).

Assessment of reporting biases

If we had been able to meta-analyse sufficient data (10 studies or more), we planned to assess reporting bias among the studies using the funnel plot method discussed in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011d). If asymmetry was noted, we planned to explore possible causes, including publication bias, poor methodological quality and true heterogeneity.

Data synthesis

We used The Cochrane Collaboration's statistical package, Review Manager, to combine outcomes when possible (RevMan 2011). We used a fixed-effect model unless substantial heterogeneity (a value of I2 greater than 50%) was obtained, in which case we used a random-effects model. For trials with more than two arms, we split the control group to avoid double counting.

We created a 'Summary of findings' table that included the following outcomes, according to the methods described in Chapter 11 of the Cochrane Handbook for Systematic Reviews of Interventions: change in Asthma Quality of Life Questionnaire (AQLQ), change in St George's Respiratory Questionnaire (SGRQ), asthma symptoms, number of acute exacerbations, inpatient hospitalisation episodes, lung function (forced expiratory volume in 1 second (FEV1)) and days off work.

Subgroup analysis and investigation of heterogeneity

If we were able to combine sufficient data and identify substantial heterogeneity (a value of I2 greater than 50%), we planned to conduct the following subgroup analyses.

  • Degree of asthma severity.

  • Age groups (adult versus elderly).

  • Duration of treatment.

Sensitivity analysis

If we had been able to combine sufficient data, sensitivity analysis would have been performed to explore the influence on the results of the following factors.

  • Trial quality (randomised controlled trials with poor methodology).

  • Trial size (stratified by sample size).

  • Allocation concealment (high risk of bias versus low risk of bias versus unclear risk of bias).

  • Assessor blinding (high risk of bias versus low risk of bias versus unclear risk of bias).

 

Results

Description of studies

Results of the search

For the initial version of the review (1998), full texts of 42 potentially relevant studies were obtained after 182 abstracts and titles revealed by the searches were screened; five studies were included (Nagarathna 1985; Girodo 1992; Fluge 1994; Bowler 1998; Vedanthan 1998). In the 2003 update, two more studies were included (Opat 2000; Thomas 2003). The search of the Airways Group Register for the 2012 update returned 147 references. Of these, twelve were identified as potentially relevant, and the full text articles were retrieved for closer inspection, of which five were new additions in the 2012 update (Holloway 2007; Thomas 2009; Sodhi 2009; Vempati 2009; Grammatopoulou 2011). A repeat search was undertaken from February 2012 to January 2013, and 12 new references were identified. Of these, three were considered eligible and thus were included in the review (Bidwell 2012; Singh 2012Prem 2013).  

We excluded two studies that were included in earlier versions of this review (see Excluded studies).

Included studies

In total, 13 studies are now included in this review: Nagarathna 1985; Girodo 1992; Fluge 1994; Vedanthan 1998; Thomas 2003; Holloway 2007; Thomas 2009; Sodhi 2009; Vempati 2009; Grammatopoulou 2011; Bidwell 2012; Singh 2012Prem 2013. See 'Characteristics of included studies' for full details on each study.

Setting and populations

Five trials were conducted in India (Nagarathna 1985; Sodhi 2009; Vempati 2009; Singh 2012Prem 2013), one in Canada (Girodo 1992), one in Germany (Fluge 1994), three in the UK (Thomas 2003; Holloway 2007; Thomas 2009), two in the USA (Vedanthan 1998; Bidwell 2012) and one in Greece (Grammatopoulou 2011). All papers were written in English with the exception of Fluge 1994, which was written in German. Nine studies were conducted between 2003 and 2013, three were conducted between 1992 and 1998 and one was conducted in 1985. The studies varied in size from 17 to 183 participants. Participants in the included studies were older than 18 years of age, with the exception of Nagarathna 1985 (aged 9 to 47), Thomas 2003 (aged 17 to 65) and Holloway 2007 (aged 16 to 70). We included all studies as the mean age was over 18.

Interventions and control groups

In seven studies (Nagarathna 1985; Fluge 1994; Vedanthan 1998; Sodhi 2009; Vempati 2009; Bidwell 2012; Singh 2012), participants undertook yoga training that involved breathing exercises as the major component, and the control groups did not undergo yoga training but continued taking their usual medication. In Nagarathna 1985, participants in the intervention group underwent training for two weeks and were told to practise these exercises for 65 minutes daily. In Fluge 1994, participants underwent 15 yoga sessions over 3 weeks. In Vedanthan 1998, yoga sessions were performed 3 times a week over 16 weeks. In Sodhi 2009, each yoga training session was of 45 minutes' duration per week with a trained instructor for a period of 8 weeks. In Vempati 2009, the intervention consisted of 2-week supervised training in lifestyle modification and stress management based on yoga followed by closely monitored continuation of these practises at home for 6 weeks. In Bidwell 2012, yoga training consisted of two 1-hour supervised yoga sessions per week for 10 weeks. In Singh 2012, participants attended yoga training provided by a yoga expert for 5 to 6 days. Thereafter, participants were told to practise yoga for an average of 40 to 50 minutes daily at home for 2 months. Participants were called to the yoga centre regularly (about every 7 days) so investigators could see whether they were doing the yoga exercises properly.

In the Girodo 1992 study, participants undertook a 16-week programme of deep diaphragmatic breathing exercises and were compared against a group of controls that were on a waiting list. Thomas 2003 compared participants who completed three short breathing retraining sessions (total contact time 75 minutes), taught by a physiotherapist, with a control group that received asthma education from a nurse. In the Holloway 2007 study, the intervention group completed five 60-minute individual sessions on the Papworth method provided by a respiratory physiotherapist. The control group received no additional treatment. In the Thomas 2009 study, the breathing training group attended three sessions (one small group session and two individual sessions) that provided an explanation of normal breathing and possible effects of abnormal 'dysfunctional breathing'. During individual sessions, participants were taught diaphragmatic and nasal breathing techniques and were encouraged to practise these exercises for at least 10 minutes per day. The control group received three sessions of nurse-provided asthma education. The intervention group in the Grammatopoulou 2011 study received twelve individual breathing retraining sessions, and the control group received usual asthma care. In the study of Prem 2013, 120 participants were divided into three groups: Buteyko, yoga and control. Participants assigned to Buteyko or yoga groups received 3 to 5 days of sessions totalling 60 minutes each day. Participants in the control group followed routine physician care involving pharmacological management.

Outcomes

The primary outcome in Holloway 2007, Thomas 2009, Bidwell 2012 and Prem 2013 was quality of life, although different instruments (SGRQ in Holloway 2007 and Bidwell 2012, and AQLQ in Thomas 2009 and Prem 2013) were used. Asthma symptoms as measured by the Asthma Control Test score were the main outcome in Grammatopoulou 2011. In Vempati 2009, pulmonary function was the primary outcome.

Secondary outcomes were asthma symptom and lung function in Holloway 2007 and Thomas 2009. Asthma symptoms were measured by the Nijmegen questionnaire in Holloway 2007 and by the Asthma Control Questionnaire in Thomas 2009. In Grammatopoulou 2011, secondary outcomes were quality of life (as measured by the Short Form (SF)-36 v2 Health Survey) and lung function. In Vempati 2009, the secondary outcome was quality of life (as measured by the AQLQ).

In the other included trials, primary and secondary outcomes were not specified, but the authors reported several main outcome measures, including pulmonary function (Fluge 1994; Sodhi 2009), asthma symptoms (Girodo 1992), number of acute exacerbations and pulmonary function (Nagarathna 1985), quality of life and asthma symptoms (Thomas 2003), asthma symptom and lung function (Vedanthan 1998), and lung function and quality of life (Singh 2012).

Excluded studies

After the full text of potentially eligible trials was retrieved, a total of 43 studies were excluded from the review. Two studies previously included were excluded in the 2012 update (Bowler 1998; Opat 2000). Reasons for exclusion are described in the Characteristics of excluded studies.

Risk of bias in included studies

Full details of risk of bias judgments can be found in Characteristics of included studies and in Figure 1.

Figure 1.

Risk of bias summary: review authors' judgements about each risk of bias item for each included study.

Allocation

Four studies reported adequate sequence generation and were judged to have low risk of bias (Thomas 2003; Holloway 2007; Grammatopoulou 2011; Prem 2013). Nine studies were reported as randomised but gave no description of the methods used and were therefore judged to be at unclear risk of bias (Nagarathna 1985; Girodo 1992; Fluge 1994; Vedanthan 1998; Sodhi 2009; Thomas 2009; Vempati 2009; Bidwell 2012; Singh 2012).

Thomas 2003 recruited individuals with high Nijmegen scores who were currently being treated for asthma at a general practice. Volunteers were randomly assigned by numbering them alphabetically and using random number tables to assign them to trial groups. In Holloway 2007, randomisation was undertaken by a computer-generated number sequence that assigned consecutive subject ID numbers a 1 or a 2 to denote intervention or a control condition. Random allocation was undertaken with sealed envelopes in Grammatopoulou 2011. In Prem 2013, participants were assigned to three groups (Buteyko, yoga and control) through block randomisation.

Only two trials described adequate allocation concealment and were then judged to have low risk of bias (Grammatopoulou 2011; Prem 2013). In Grammatopoulou 2011, allocation concealment was undertaken with sealed envelopes, and in Prem 2013, the method of allocation was concealed in sequentially numbered, sealed, opaque envelopes. The other eleven studies gave no description of the methods of allocation concealment used and were therefore judged to have unclear risk of bias (Nagarathna 1985; Girodo 1992; Fluge 1994; Vedanthan 1998; Thomas 2003; Holloway 2007; Thomas 2009; Vempati 2009; Sodhi 2009; Bidwell 2012; Singh 2012).

Blinding

A study is classed as double-blinded if neither the investigator nor the participant involved knows the identity of the intervention. Blinding reduces bias in a trial. Double-blinding is not possible or practical in these studies. Participants in these trials must know whether or not they are undertaking breathing training or asthma education, as compliance is critical to the study. However, it is possible to blind the assessor who is analysing the results of the trial.

Five trials described that the blinding of participants and personnel was not possible; these studies were judged to have a high risk of bias, as it was determined that the outcomes may be influenced by the lack of blinding (Thomas 2003; Holloway 2007; Thomas 2009; Vempati 2009; Grammatopoulou 2011). Eight studies did not describe blinding of participants and personnel, so they were judged to have an unclear risk of bias (Nagarathna 1985; Girodo 1992; Fluge 1994; Vedanthan 1998; Sodhi 2009; Bidwell 2012; Singh 2012; Prem 2013).

Blinding of outcome assessors was described in five studies (Vedanthan 1998; Thomas 2003; Holloway 2007; Grammatopoulou 2011; Prem 2013). In Grammatopoulou 2011, participants were assessed by the same trained assessor, who was blinded to the participants' treatment allocation. In Thomas 2003, questionnaires completed by the participants were scored by the blinded investigator. In Vedanthan 1998, records of the yoga and control groups were coded during the study period, and the decoded data were unavailable to the principal investigators. In Prem 2013, the parameters were recorded before and after training by a person blinded to the allocation of groups. Eight studies did not describe blinding of outcome assessment, so they were judged to have an unclear risk of bias (Nagarathna 1985; Girodo 1992; Fluge 1994; Thomas 2003; Vempati 2009; Sodhi 2009; Bidwell 2012; Singh 2012).  

Incomplete outcome data

Two studies did not describe the occurrence of withdrawals and dropouts and were judged to be at unclear risk of bias (Girodo 1992; Sodhi 2009). The study of Nagarathna 1985 affirmed that in total 25 participants dropped out of the study. However, this study was judged to have an unclear risk of bias because it did not describe how many participants dropped out of the study in each group (intervention and control). In three studies, no withdrawals or dropouts were reported; these studies were judged to have a low risk of bias (Vedanthan 1998; Grammatopoulou 2011; Bidwell 2012). Seven studies described withdrawals and dropouts and were also judged to have a low risk of bias because the missing outcome data were balanced in numbers across intervention groups (Thomas 2003; Holloway 2007; Thomas 2009; Vempati 2009) or because the reasons for missing outcome data were unlikely to be related to true outcomes (Fluge 1994; Singh 2012; Prem 2013).

Selective reporting

Two studies were registered on clinicaltrials.gov, and all of the prespecified primary and secondary outcomes were reported in a prespecified way (Holloway 2007; Vempati 2009). These studies were judged to have a low risk of bias. Six studies adequately reported outcome data for all primary and secondary outcomes as listed in the methods, although the protocol for each study is not available ( Nagarathna 1985; Thomas 2003; Thomas 2009; Sodhi 2009; Grammatopoulou 2011; Singh 2012). Five studies were judged to be at high risk of bias because one or more outcomes of interest in the review were reported incompletely, so that they cannot be entered into a meta-analysis (Girodo 1992; Fluge 1994; Vedanthan 1998; Bidwell 2012; Prem 2013).

Other potential sources of bias

We were unable to identify any other potential biases in four studies (Thomas 2003; Holloway 2007; Grammatopoulou 2011; Prem 2013). Nine studies were judged to be at unclear risk of bias, as they did not provide sufficient information to allow assessment of whether an important risk of bias is present (Nagarathna 1985; Girodo 1992; Fluge 1994; Vedanthan 1998; Thomas 2009; Sodhi 2009; Vempati 2009; Bidwell 2012; Singh 2012).

Effects of interventions

See: Summary of findings for the main comparison

Breathing exercises versus inactive control

Primary outcome: quality of life

Six studies involving 381 participants reported improvement in quality of life in the groups that submitted to breathing exercises (Holloway 2007; Vempati 2009; Grammatopoulou 2011; Bidwell 2012; Singh 2012; Prem 2013). One study (Holloway 2007) reported data at baseline and at 6 and 12 months after baseline; one (Grammatopoulou 2011) at baseline and at 1, 2 and 6 months; and one (Vempati 2009) at baseline and at 2, 4 and 8 weeks. In Bidwell 2012, Singh 2012 and Prem 2013, data were reported at baseline and at post-treatment. Three of these studies (Holloway 2007; Vempati 2009; Prem 2013) were included in the meta-analysis. However, the studies of Vempati 2009 and Prem 2013 assessed quality of life by the AQLQ, and the study of Holloway 2007 assessed this outcome by the SGRQ. When the AQLQ showed the opposite direction of effect to the SGRQ, these questionnaires were analysed separately.

For the outcome 'Change in AQLQ' (Analysis 1.1), which included the studies of Vempati 2009 and Prem 2013, meta-analysis showed significant differences favouring the breathing exercises group (MD 0.79, 95% CI 0.50 to 1.08). The postintervention values for the AQLQ in the study of Prem 2013 were provided by the author as means and standard deviations.

The statistical analysis for the SGRQ in the study of Holloway 2007 has a P value that has been adjusted for a baseline covariate. However, the adjusted mean difference was not given in this study. Thus, after the adjusted mean difference was calculated, the analysis for the outcome ‘Change in SGRQ’ (Analysis 1.2)  yielded a P value smaller than the 0.186 reported in the paper (6 months post-baseline), whereas no difference was seen in the final scores analysis (12 months post-baseline).

We were not able to include the other three studies in the meta-analysis (Grammatopoulou 2011; Bidwell 2012; Singh 2012). Of these, Grammatopoulou 2011 showed that the group that performed breathing exercises showed improvement in the physical component of the SF-36 quality of life questionnaire compared with controls in all assessments (2, 3 and 6 months after intervention, with P values of 0.003, 0.0002 and 0.066, respectively). Bidwell 2012 found significant improvement in the three aspects of the SGRQ (symptoms, activity and impact) in the yoga group compared with the control group (P < 0.05). Singh 2012 observed a significant difference favouring the group submitted to the intervention, with a P value ˂ 0.001 for all four domains of the AQLQ.

Holloway 2007 also assessed the Hospital Anxiety and Depression Score (HADS). This study found significantly lower HADS scores in the intervention group than in the control group, with a P value of 0.002 for HADS Anxiety score and of 0.075 for HDAS Depression score at 6 months post-baseline assessment. At 12 months post-baseline assessment, significant differences favoured the intervention group, with P = 0.772 for the HADS Anxiety score and P < 0.001 for the HADS Depression score.

Secondary outcome: asthma symptoms

Five studies involving 331 participants reported asthma symptoms (Girodo 1992; Vedanthan 1998; Holloway 2007; Grammatopoulou 2011; Prem 2013). Meta-analysis was possible for two studies for this outcome (Holloway 2007; Grammatopoulou 2011) (Analysis 1.3; Figure 2). Assessment of heterogeneity revealed no significant difference between these two studies (I2 = 0%). Meta-analysis showed significant differences favouring the breathing exercises group (MD -3.22, 95% CI -6.31 to -0.13). The other three studies (Girodo 1992; Vedanthan 1998; Prem 2013) did not report sufficient data to enter the meta-analysis. Of these, one study reported no significant difference in asthma symptoms between yoga and control groups (Vedanthan 1998). Girodo 1992 did not observe significant changes in frequency of symptoms on the Asthma Symptom Checklist in any group. However, this study also reported that significant differences (P < 0.03) favoured the intervention group for attack intensity scores (Girodo 1992). In Prem 2013, the comparison between baseline and postintervention values showed that the Buteyko group had better trends toward improvement in total Asthma Control Questionnaire (ACQ) score (P = 0.001) than the pranayama (P = 0.356) and control groups (P = 0.383). The study of Prem 2013 did not provide between-group analyses for this outcome.

Figure 2.

Forest plot of comparison: 1 Breathing exercises versus inactive control, outcome: 1.3 Asthma symptoms.

Secondary outcome: number of acute exacerbations

Only one study reported this outcome (Nagarathna 1985). Over two weeks, the intervention group involving 53 participants attended a daily yoga programme lasting two and a half hours. Comparison between the two groups (yoga and control) showed significant improvement (P < 0.005) in the number of exacerbations in the group that received the intervention (Nagarathna 1985). 

Secondary outcome: physiological measures

Six studies involving 462 participants reported improvement in spirometry in the groups that performed the intervention (Nagarathna 1985; Sodhi 2009; Vempati 2009; Grammatopoulou 2011; Bidwell 2012; Prem 2013). Four studies did not show significant differences in this outcome (Fluge 1994; Vedanthan 1998; Holloway 2007; Singh 2012). Only two of the ten studies (Sodhi 2009; Vempati 2009) were included in the meta-analysis (Analysis 1.4, Analysis 1.5, Analysis 1.6, Analysis 1.7; Analysis 1.8). However, because of the substantial heterogeneity indicated by an I2 statistic greater than 50% for all variables evaluated in spirometry (peak expiratory flow (PEF), forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), FEV1/FVC, air flow in the middle of a forced exhalation (FEF25-75%)), data could not be pooled. This heterogeneity may be attributed to methodological differences in the studies, such as duration of intervention (duration of 45 minutes for 8 weeks vs 4 hours for 2 weeks) for Sodhi 2009 and Vempati 2009, respectively.

Two studies also assessed capnography (Holloway 2007; Grammatopoulou 2011). The study of Holloway 2007 did not find significant differences between intervention and control groups regarding end-tidal carbon dioxide. However, values for relaxed breathing rate over a 10-minute period showed better results in the intervention group than in the control group, with P < 0.001 at 6- and 12-month post-baseline assessments. In the study of Grammatopoulou 2011, the intervention group compared with the control group showed increased end-tidal carbon dioxide (P = 0.002 and 0.003 for 1- and 6-month post-baseline assessments, respectively; P < 0.0001 for 2-month post-baseline assessment). The intervention group showed a decreased respiratory rate compared with the control group (P < 0.0001).

Secondary outcomes: inpatient hospitalisation episodes, GP appointments, days off work and subjective evaluation of the intervention

These outcomes were not reported in any of the studies.

Breathing exercises versus asthma education

Primary outcome: quality of life

Two studies involving 194 participants assessed this outcome (Thomas 2003; Thomas 2009). Both studies had follow-up periods of 1 and 6 months. The study of Thomas 2003 showed a statistically significant improvement (P = 0.018) in overall AQLQ scores in the intervention group compared with the control group after 1 month. After 6 months, only the improvement in the activities domain of the AQLQ was significantly greater in the intervention group than in the control group (P = 0.018). The study of Thomas 2009 showed no significant between-group differences in the four subdomains of the AQLQ at 1-month assessment. At 6 months, significantly greater improvements were found in the intervention group in terms of symptoms (P = 0.01), activities (P = 0.01) and emotions (P = 0.05) domains but not in the environment domain (P = 0.40) compared with controls, with a significant between-groups difference favouring the intervention group (P = 0.01) for the total score (see Analysis 2.1).

Thomas 2009 also assessed the Hospital Anxiety and Depression Score (HADS). This study found significant reductions in HAD Anxiety and Depression domain scores in both groups 1 month after the intervention, with no significant difference noted between the groups. At the 6-month assessment, significant between-group differences were observed to favour the intervention group for Anxiety score (P = 0.02) and Depression score (P = 0.03).

Secondary outcome: asthma symptoms

Two studies involving 194 participants assessed asthma symptoms (Thomas 2003; Thomas 2009). Both studies carried out assessment of symptoms at baseline and 1 month and 6 months after the intervention (Thomas 2003; Thomas 2009). In Thomas 2003, the between-group difference favouring the intervention was statistically significant only after 6 months (P = 0.01). In Thomas 2009, no between-group difference was noted for the ACQ, whereas a statistically significant difference favoured the intervention group at 6-month assessment for the Nijmegen Questionnaire (P = 0.005).

Secondary outcome: physiological measures

Only one study assessed spirometric values (Thomas 2009). This study assessed FEV1 by checking that no significant difference (P = 0.07) was evident between the intervention and control groups.

The study of Thomas 2009 also assessed resting end-tidal carbon dioxide concentration, showing that values for this outcome did not change significantly within or between groups.

Secondary outcomes: numbers of acute exacerbations, inpatient hospitalisation episodes, GP appointments and days off work and subjective evaluation of the intervention

These outcomes were not reported in these two studies.

Discussion

Summary of main results

This systematic review assessed available evidence for the efficacy of breathing exercises in the treatment of patients with asthma. A total of 13 studies involving 906 participants satisfied the inclusion criteria. Although these studies met the inclusion criteria, they differed significantly in terms of intervention characteristics, such as type of breathing exercise, number of participants, number and duration of sessions, reported outcomes and statistical presentation of data. These differences limited meta-analysis.  

The included studies reported that breathing exercises were well tolerated by participants, and no adverse effects related to the intervention were described, showing that this is a safe non-pharmacological intervention. All eight studies that assessed quality of life reported improvement in this outcome. Improvement in the number of acute exacerbations was observed by the only study that assessed this outcome. Six of seven included studies showed a significant difference favouring breathing exercises for asthma symptoms. Effects on lung function were more variable, with no difference noted in five of the eleven studies that assessed this outcome, although the other six showed a significant difference for this outcome that favoured breathing exercises.

Because the included studies employed different interventions by using different methodologies, meta-analysis for lung function was not possible because of high heterogeneity. For asthma symptoms and changes in AQLQ, meta-analysis showed improvement favouring the group that submitted to breathing exercises. However, each meta-analysis was performed with only two studies.

Overall completeness and applicability of evidence

The types of breathing exercises that were related to improvements in quality of life, asthma symptoms and numbers of exacerbations were the Papworth method, Buteyko, diaphragmatic breathing and yoga. The ones that improved lung function were Buteyko, yoga and diaphragmatic breathing. However, the effects seen may represent a combination of many characteristics rather than breathing exercises alone. Some of the included studies involved group sessions in which participants were able to talk to each other and share their experiences. This can also be considered a therapeutic procedure that may affect the sensation of well-being (Evans 1993). Awareness of participation in the study, the sensation of increased care and cure and the specialists’ recommendations to continue regular asthma medication are characteristics that must be considered when the findings of an experimental study are interpreted (Grammatopoulou 2011).

Moreover, asthma severity of participants from the included studies ranged from mild to moderate, so it was not possible to assess the effects of breathing exercises on participants with severe asthma. The samples from studies consisted solely of outpatients. Besides that, four of the eight outcomes proposed by this review were not addressed: inpatient hospitalisation episodes, reduction in general practice (GP) and hospital outpatient appointments, days off work and participants' subjective evaluation of the intervention. 

Quality of the evidence

This systematic review was limited by the quality of existing data. Some points must be taken into consideration when the results of this review are analysed, including small sample size and small number of sessions of some studies coupled with limitations in the design and reporting of studies, leading to risk of bias.

In general, the included studies had a small number of participants. The impact of a small sample size on trial results was already reported in a previous study (Moher 1994), which reviewed 383 randomised controlled trials. This study concluded that most trials with negative results did not have large enough sample sizes to detect relative differences. Furthermore, the description of how sample size was determined is recommended by the CONSORT statement (CONSORT 2010). Three of the included studies performed sample size and power calculations: Thomas 2003 (based on AQLQ), Holloway 2007 (based on SGRQ) and Grammatopoulou 2011 (based on ACT). Moreover, the number of sessions involved in these studies was small, given the longer duration of 6 months.

Of the thirteen studies included in the review, only four described the method of random sequence generation and were classified as “low risk of bias”. In addition, the allocation concealment was described in only two studies, which had a low risk of bias for this item. According to Savović 2012, inadequate reporting of trial methods can severely impede assessment of trial quality and of risk of bias in trial results. According to this study, this is a particular problem for the assessment of sequence generation and allocation concealment, which often are not described in trial publications (Savović 2012). In addition, inadequately reported randomisation has been associated with bias in estimating the effectiveness of interventions (Moher 2001).

In a randomised controlled trial, at least three distinct groups (trial participants, trial personnel and outcome assessors) can potentially be blinded (Savović 2012). When a randomised controlled study that involves breathing exercises is conducted, it is not possible for the participants and the personnel to be blinded to the intervention (Holloway 2007). According to Savović 2012, the lack of or unclear double blinding (participants and personnel) can be associated with marked exaggeration of intervention effect estimates.

Potential biases in the review process

Although an attempt was made to apply a systematic process for including and excluding studies in this review, besides following the criteria prespecified in the protocol with robust methods for data collection and risk of bias assessment, final decisions are open to interpretation or criticism.

Incomplete outcome data may be considered a potential source of bias of this review. This factor has also limited analysis, as the data from these studies could not be entered into a meta-analysis. Also related to meta-analysis, the subgroup and the sensitivity analysis were not possible because of the impossibility of obtaining sufficient data. This could have showed possible differences in degree of asthma severity, age groups and duration of treatment. Moreover, sensitivity analysis could have identified the influence of some factors (such as trial quality and trial size) on the results, thus revealing a source of the substantial heterogeneity found among studies on lung function.  

Agreements and disagreements with other studies or reviews

The current review update included eight new randomised controlled trials and removed two trials that were included in the last published version of this review. In addition, this review brings together trials that were not included in previous systematic reviews (Ernst 2000; Ram 2003). These two reviews assessed the effectiveness of breathing exercises in the management of asthma. The outcomes assessed by Ernst 2000 were asthma symptoms and lung function, and those assessed by Ram 2003 were quality of life, asthma symptoms, number of exacerbations and lung function.

The findings of this review show that, even though outcomes reported by individual trials showed improvement in quality of life indices, asthma symptoms, number of exacerbations and lung function of participants who submitted to breathing exercises, evidence supporting the efficacy of breathing exercises in these outcomes is not sufficient. The systematic review performed by Ernst 2000 affirmed that, on the basis of available data, it was not possible to make firm judgments. Also, this review suggested that breathing techniques seem to have some potential and should be tested rigorously in the future. Similarly, the systematic review performed by Ram 2003 concluded that because evidence available from the small randomised controlled trials included in the review is limited, it was not possible to draw any firm conclusions as to the effectiveness of breathing exercises in the treatment and management of asthma.

It is important to emphasise that, even though the results of this review are consistent with results reported by the two previous systematic reviews (Ernst 2000; Ram 2003), some methodological differences have been noted among these studies. The review of Ernst 2000 was published more than one decade ago. Moreover, this review included two cross-over studies and one study that was performed with children admitted to hospital with acute severe asthma. Ram 2003 included only six studies, which did not involve the same breathing exercise techniques that were examined by the present review, such as the Papworth method.

Authors' conclusions

Implications for practice

This review indicates that breathing exercises are a safe and well-tolerated intervention for people with asthma. Also, meta-analysis of two studies showed that breathing exercises may have positive effects on asthma symptoms and quality of life (more specifically, on AQLQ score). Even though outcomes that were reported from individual trials show that breathing exercises may have a role in the treatment and management of asthma, no conclusive evidence is provided in this review to support or refute the benefits of these techniques in terms of quality of life, asthma symptoms, number of exacerbations and lung function. This is a result of the small number of participants in most of the included studies, the small number of sessions, the methodological differences among included studies, trials with poor methodology and the statistical heterogeneity noted among the studies for three of the four outcomes assessed by meta-analysis. No data are available regarding the effects of breathing exercises on inpatient hospitalisation episodes, reduction in GP and hospital outpatient appointments, days off work and participants' subjective evaluation of the intervention.

Implications for research

Well-conducted randomised controlled trials are needed to assess the clinical benefit of breathing exercises in the management of asthma, including those that were not assessed by the studies included in this review such as inpatient hospitalisation episodes, reduction in GP and hospital outpatient appointments, days off work and participants' subjective evaluation of the intervention. Furthermore, in the future, much more attention needs to be paid to good reporting and high-quality study design, including items such as adequate random sequence generation and allocation concealment, blinding of outcome assessor and determination of the trial sample size before the study is begun.

Acknowledgements

The authors would like to thank Emma Welsh (the Managing Editor of the Cochrane Airways Group) for providing assistance throughout the review process and Elizabeth Stovold (the Trials Search Co-ordinator/Information Specialist of the Cochrane Airways Group) for performing the search. 

We would also like to thank all the authors who responded to our enquiries.

Anne Holland was the Editor for this review. Anne commented critically on the review and assisted the Co-ordinating Editor with signing off on the review for publication.

Data and analyses

Download statistical data

Comparison 1. Breathing exercises versus inactive control
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Change in AQLQ2172Mean Difference (IV, Fixed, 95% CI)0.79 [0.50, 1.08]
1.1 Buteyko159Mean Difference (IV, Fixed, 95% CI)0.98 [0.55, 1.41]
1.2 Pranayama156Mean Difference (IV, Fixed, 95% CI)0.5 [0.04, 0.96]
1.3 Yoga157Mean Difference (IV, Fixed, 95% CI)0.96 [0.28, 1.64]
2 Change in SGRQ1 Mean Difference (IV, Fixed, 95% CI)Subtotals only
2.1 6 months post baseline178Mean Difference (IV, Fixed, 95% CI)-5.9 [-12.64, 0.84]
2.2 12 months post baseline172Mean Difference (IV, Fixed, 95% CI)-5.00 [-13.97, -0.03]
3 Asthma symptoms2118Mean Difference (IV, Fixed, 95% CI)-3.22 [-6.31, -0.13]
4 Lung function (PEF)2 Mean Difference (IV, Random, 95% CI)Totals not selected
5 Lung function (FVC)2 Mean Difference (IV, Random, 95% CI)Totals not selected
6 Lung function (FEV1)2 Mean Difference (IV, Random, 95% CI)Totals not selected
7 Lung function (FEV1/FVC)2 Mean Difference (IV, Random, 95% CI)Totals not selected
8 Lung function (FEF25-75%)2 Mean Difference (IV, Random, 95% CI)Totals not selected
Analysis 1.1.

Comparison 1 Breathing exercises versus inactive control, Outcome 1 Change in AQLQ.

Analysis 1.2.

Comparison 1 Breathing exercises versus inactive control, Outcome 2 Change in SGRQ.

Analysis 1.3.

Comparison 1 Breathing exercises versus inactive control, Outcome 3 Asthma symptoms.

Analysis 1.4.

Comparison 1 Breathing exercises versus inactive control, Outcome 4 Lung function (PEF).

Analysis 1.5.

Comparison 1 Breathing exercises versus inactive control, Outcome 5 Lung function (FVC).

Analysis 1.6.

Comparison 1 Breathing exercises versus inactive control, Outcome 6 Lung function (FEV1).

Analysis 1.7.

Comparison 1 Breathing exercises versus inactive control, Outcome 7 Lung function (FEV1/FVC).

Analysis 1.8.

Comparison 1 Breathing exercises versus inactive control, Outcome 8 Lung function (FEF25-75%).

Comparison 2. Breathing exercises versus asthma education
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Change in AQLQ1 Mean Difference (Fixed, 95% CI)0.38 [0.08, 0.68]
Analysis 2.1.

Comparison 2 Breathing exercises versus asthma education, Outcome 1 Change in AQLQ.

Appendices

Appendix 1. Sources and search methods for the Cochrane Airways Group Specialised Register (CAGR)

Electronic searches: core databases

Database Frequency of search
CENTRAL (The Cochrane Library)Monthly
MEDLINE (Ovid)Weekly
EMBASE (Ovid)Weekly
PsycINFO (Ovid)Monthly
CINAHL (EBSCO)Monthly
AMED (EBSCO)Monthly

 

Handsearches: core respiratory conference abstracts

Conference Years searched
American Academy of Allergy, Asthma and Immunology (AAAAI)2001 onwards
American Thoracic Society (ATS)2001 onwards
Asia Pacific Society of Respirology (APSR)2004 onwards
British Thoracic Society Winter Meeting (BTS)2000 onwards
Chest Meeting2003 onwards
European Respiratory Society (ERS)1992, 1994, 2000 onwards
International Primary Care Respiratory Group Congress (IPCRG)2002 onwards
Thoracic Society of Australia and New Zealand (TSANZ)1999 onwards

 

MEDLINE search strategy used to identify trials for the CAGR

Asthma search

1. exp Asthma/

2. asthma$.mp.

3. (antiasthma$ or anti-asthma$).mp.

4. Respiratory Sounds/

5. wheez$.mp.

6. Bronchial Spasm/

7. bronchospas$.mp.

8. (bronch$ adj3 spasm$).mp.

9. bronchoconstrict$.mp.

10. exp Bronchoconstriction/

11. (bronch$ adj3 constrict$).mp.

12. Bronchial Hyperreactivity/

13. Respiratory Hypersensitivity/

14. ((bronchial$ or respiratory or airway$ or lung$) adj3 (hypersensitiv$ or hyperreactiv$ or allerg$ or insufficiency)).mp.

15. ((dust or mite$) adj3 (allerg$ or hypersensitiv$)).mp.

16. or/1-15

Filter to identify RCTs

1. exp "clinical trial [publication type]"/

2. (randomised or randomised).ab,ti.

3. placebo.ab,ti.

4. dt.fs.

5. randomly.ab,ti.

6. trial.ab,ti.

7. groups.ab,ti.

8. or/1-7

9. Animals/

10. Humans/

11. 9 not (9 and 10)

12. 8 not 11

The MEDLINE strategy and RCT filter are adapted to identify trials in other electronic databases.

What's new

DateEventDescription
30 January 2013New search has been performedLiterature search run.
30 January 2013New citation required and conclusions have changedEight new studies included; two formerly included studies excluded. New author team. Title changed to specify that the review pertains to adults only. Summary of findings table added.

History

Protocol first published: Issue 4, 1998
Review first published: Issue 3, 2000

DateEventDescription
21 July 2008AmendedConverted to new review format.
16 September 2003New citation required and conclusions have changedSubstantive amendment

Contributions of authors

Diana Freitas: selected the studies, extracted data, entered data into RevMan, carried out the analysis, interpreted data and drafted the final review.

Elizabeth Holloway: drafted the original review and contributed her clinical expertise.

Selma Bruno: contributed with clinical expertise, carried out the analysis, interpreted data and drafted the final review.

Gabriela Chaves: selected the studies, extracted data, entered data into RevMan, carried out the analysis, interpreted data and drafted the final review.

Guilherme Fregonezi: contributed with clinical expertise and drafted the final review.

Karla Mendonça: coordinated the review, made an intellectual contribution, interpreted data and drafted the final review.

Declarations of interest

None known.

Characteristics of studies

Characteristics of included studies [ordered by study ID]

Bidwell 2012

Methods

Design: randomised controlled trial

Method of randomisation: not described

Method of allocation concealment: not described

Outcome assessor blinding: not described

Withdrawals/dropouts: none

Participants

Country: USA
Setting: Human Performance Laboratory
Health status: mild to moderate asthma
This trial included 2 arms (yoga and control group)
Total sample: 19 female participants
Mean age, years: 43 ± 4 (yoga group) and 40 ± 4 (control group)

Age range, years: 20 to 65
Exclusion criteria: Participants were excluded if they were smokers, participated in yoga therapy in the previous 12 months, were diagnosed as having hypertension or major orthopaedic injuries prohibiting the performance of various yoga postures and/or were currently taking any medications that would alter autonomic function

Interventions

Active treatment: Yoga training consisted of two 1-hour supervised yoga sessions/wk for 10 weeks. Additionally, participants were required to perform one 30-minute session/wk at home, which was based on a written lesson plan (5 minutes of deep breathing, 20 minutes of asanas and 5 minutes of meditation and relaxation)

Control group: Participants were instructed not to participate in yoga or related breathing practises for the duration of the study

Outcomes

Quality of life (St George’s Respiratory Questionnaire)

Spirometry response

NotesWe have written to the author for further clarification regarding total sample size and the values of the SGRQ and the pulmonary function test
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskThe method of sequence generation is not described
Allocation concealment (selection bias)Unclear riskThe method of concealment is not described
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskInsufficient information to permit judgement of ‘low risk’ or ‘high risk'
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskInsufficient information to permit judgement of ‘low risk’ or ‘high risk'
Incomplete outcome data (attrition bias)
All outcomes
Low riskNo missing outcome data
Selective reporting (reporting bias)High riskOne or more outcomes of interest in the review are reported incompletely, so that they cannot be entered into a meta-analysis
Other biasUnclear riskInsufficient information to assess whether an important risk of bias exists

Fluge 1994

MethodsDesign: randomised controlled trial over 3 weeks
Method of randomisation: randomly assigned into three equal groups (12 × 3)
Method of allocation concealment: not described
Outcome assessor blinding: not described
Withdrawals/dropouts: 3 dropouts described in the control group
(This paper was translated from German)
Participants

Country: Germany
Setting: community
Health status: mild asthma
This trial included 3 arms (yoga, physiotherapy and physical exercises and control group). Two arms were included in the review (yoga and control groups).
Total sample: 36 participants (14 males and 22 females)
Mean age, years: 48.8 ±1.8

Age range, years: 21 to 55
12 participants in each group

Exclusion criteria: cardiopulmonary complications due to asthma, exacerbation 8 weeks before the beginning of the study, smoke

Interventions

Active treatment: 3 weeks' training of 3 hours, 15 times total
Intervention group: Yoga consisted of Asana, Mudra, Pranayama, Kriya and Yoga Nidra

Control group received no additional treatment
Participants were re-evaluated after 15 sessions

OutcomesSpirometry
NotesWe have written to the author for further clarification
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskThe method of sequence generation is not described
Allocation concealment (selection bias)Unclear riskThe method of concealment is not described
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskInsufficient information to permit judgement of ‘low risk’ or ‘high risk'
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskInsufficient information to permit judgement of ‘low risk’ or ‘high risk
Incomplete outcome data (attrition bias)
All outcomes
Low riskReasons for missing outcome data unlikely to be related to true outcome
Selective reporting (reporting bias)High riskOne outcome of interest in the review is reported incompletely
Other biasUnclear riskInsufficient information to assess whether an important risk of bias exists

Girodo 1992

Methods

Design: randomised controlled trial over 16 weeks

Method of randomisation: not described
Method of allocation concealment: not possible
Outcome assessor blinding: not described
Withdrawals/dropouts: not described

Participants

Country: Canada
Setting: community
Time: December to May
Participants: from media solicitations for asthmatic participants, 274 respondents
Eligible: 92
Randomly assigned: 92 to 4 groups
Providers: 2 deep diaphragmatic breathing (DDB) groups, one taught by a singing instructor, the other by a 25-year-old participant with asthma. Physical education group led by student with PE experience. Control group: waiting list participants. Three arms were included in the review (the deep diaphragmatic breathing groups and the control groups)
Data at the end of the 2-week run-in period:

  • DDB groups: n = 32: 20 (62%) female

    • Mean age, years: 28.61 (11.21)

  • PE group: n = 12: 8 (66%) female

    • Mean age, years: 34.92 (10.53)

  • Waiting list control group: n = 23: 13 (56% female)

    • Mean age, years: 32.9 (6.55)

  • Inclusion criteria: detailed examination of the history of their condition—doctor's approval and informed consent

  • Exclusion criteria: history of allergies, severe asthma, chest disease, diabetes, inability to make 26-week commitment

Interventions

Duration: active treatment: 16 weeks' training of one hour 3 times a week
Breathing groups: physical and respiratory exercises to enlarge the thoracic cage and increase the capacity for maximum lung efficiency during expiration
PE group: physical exercises with no emphasis on deep diaphragmatic breathing
Control/placebo: waiting list controls had pretest assessment of 'chronicled' medication use and asthma symptoms
Re-evaluated after 8 and 16 weeks
Co-intervention: no information given

Data from the 2 breathing groups were combined

OutcomesAsthma symptom checklist
NotesWe have written to the author to ask for information on randomisation methods and further data
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskMethod of sequence generation not described
Allocation concealment (selection bias)Unclear riskMethod of allocation concealment not described
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskInsufficient information to permit judgement of ‘low risk’ or ‘high risk
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskInsufficient information to permit judgement of ‘low risk’ or ‘high risk’
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskInsufficient information to permit judgement of ‘low risk’ or ‘high risk’
Selective reporting (reporting bias)High riskOne outcome of interest in the review is reported incompletely, so that it cannot be entered into a meta-analysis
Other biasUnclear riskInsufficient information to assess whether an important risk of bias exists

Grammatopoulou 2011

Methods

Design: randomised controlled trial over 6 months

Method of randomisation: undertaken with sealed envelopes

Method of allocation concealment: undertaken with sealed envelopes

Outcome assessor blinding: Assessors were blinded to the participants' treatment allocation

Withdrawals/dropouts: none

Participants

Country: Greece

Setting: outpatient

Health status: mild to moderate asthma

Mean age, years: 45.45 ± 12.67 (control group) and 48.15 ± 14.63 (intervention group)

Age range, years: 18 to 60

Gender: 10 males and 10 females (control group), 13 males and 7 females (intervention group)

Total sample: 40 participants

Exclusion criteria: individuals older than 60 years, smokers, use of oral corticosteroids in the previous 3 months, heart disease, participation in a prior asthma education programme

Interventions

The intervention consisted of two phases:

  • The first phase (1 month) consisted of a 60-minute, small-group session (five participants/group) in which participants were educated in (1) the “normal” breathing pattern, as well as the pattern during exacerbations, (2) recognising asthma symptoms, and (3) comprehending their ability to modify their breathing pattern while targeting self-management of the symptoms and expressing their perceived severity of asthma and the benefits and barriers of adapting a modified breathing pattern for a 6-month period. This phase also included twelve individual sessions (three/wk), each of nearly 1 hour duration, comprising education and practise of (1) diaphragmatic breathing, (2) nasal breathing, (3) short hold of breath (2 to 3 seconds) and (4) adaptation of the speech pattern (speaking, singing), in any position, during physical activity and in asthma exacerbation

  • The second phase (5 months) consisted of instructions regarding the duration (20 minutes at least) and frequency (2 to 3 times/day) of training at home for the remaining months, as well as adaptation of breathing behavior during leisure-time physical activities

The control group received no additional treatment

Outcomes

Quality of life (as measured by the SF-36 questionnaire)

Asthma control was measured by the Asthma Control Test (ACT), whose score ranges from 5 (poorly controlled) to 25 (completely controlled)

Nijmegen Questionnaire (used to screen for the hyperventilation syndrome)

Spirometry

Capnography

NotesThe author responded to our request regarding further clarification about the scores of the SF-36 questionnaire
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskRandom allocation was undertaken with sealed envelopes
Allocation concealment (selection bias)Low riskAllocation concealment was undertaken with sealed envelopes
Blinding of participants and personnel (performance bias)
All outcomes
High riskNo blinding of participants and personnel, and the outcome is likely to be influenced by lack of blinding
Blinding of outcome assessment (detection bias)
All outcomes
Low riskParticipants were assessed by the same trained assessor, blinded to the participants' treatment allocation
Incomplete outcome data (attrition bias)
All outcomes
Low riskNo missing outcome data
Selective reporting (reporting bias)Low riskThe study protocol is not available, but the published reports include all expected outcomes, including those that were prespecified
Other biasLow riskThe study appears to be free of other sources of bias

Holloway 2007

Methods

Design: randomised controlled trial over five sessions

Method of randomisation: undertaken by a computer-generated number sequence assigning consecutive participant ID numbers a 1 or a 2 to denote intervention or control condition

Method of allocation concealment: not described

Outcome assessor blinding: not possible

Withdrawals/dropouts: 13 participants dropped out (7 after 6 months and 6 after 12 months)

Participants

Country: England, UK

Setting: semi-rural GP practise

Health status: mild to moderate asthma

Mean age, years: 49.3 ± 14.2 (control group) and 50.2 ± 14.0 (intervention group)

Gender: 18 males and 28 females (control group), 18 males and 21 females (intervention group)

Total sample: 85 participants

Inclusion criteria: participants aged 16 to 70 years; able to understand, read and write English, with a commitment to participate for possibly eight attendances; willing to give written informed consent and with no serious comorbidity

Interventions

The intervention group received five 60-minute individual sessions on the Papworth method from a respiratory physiotherapist. The Papworth method consisted of five components: breathing training, education, relaxation training, integration of 'appropriate' breathing and relaxation techniques into daily living activities and home exercises (audiotape or CD containing reminders of the breathing and relaxation techniques)

The control group received no additional treatment

Assessments took place at baseline and at 6 and 12 months after baseline

Outcomes

Quality of life as measured by the St George’s Respiratory Questionnaire (SGRQ), which assesses impaired respiratory symptoms and quality of life related to these

Hypocapnic symptoms as assessed by the Nijmegen Questionnaire

Hospital Anxiety and Depression Score (HADS)

Spirometry

Capnography

NotesN/A
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskRandomisation was undertaken by a computer-generated number sequence
Allocation concealment (selection bias)Unclear riskInsufficient information to permit judgement of ‘low risk’ or ‘high risk”
Blinding of participants and personnel (performance bias)
All outcomes
High riskNo blinding of participants and personnel, and the outcome is likely to be influenced by lack of blinding
Blinding of outcome assessment (detection bias)
All outcomes
High riskBlinding of outcome assessment was not possible, and the outcome measurement may be influenced by lack of blinding
Incomplete outcome data (attrition bias)
All outcomes
Low riskMissing outcome data balanced in numbers across intervention groups (seven from the intervention group and six from the control group), with similar reasons for missing data across groups
Selective reporting (reporting bias)Low riskThe study protocol is available, and all of the study’s prespecified (primary and secondary) outcomes that are of interest in the review have been reported in the prespecified way
Other biasLow riskThe study appears to be free of other sources of bias

Nagarathna 1985

Methods

Design: randomised controlled trial over two weeks

Method of randomisation: not described

Method of allocation concealment: not described

Outcome assessor blinding: not described

Withdrawals/dropouts: Participants who stopped practicing or did not practise for more than 16 days each month were eliminated from the study. No other reason for attrition was noted. 25 dropped out: 7 after 6 months, 7 after 12 months, 2 after 18 months 4 after 24 months and 5 after 30 months

Participants

Country: India

Setting: Yoga Therapy and Research Centre

Participants: n = 106

Yoga group: n = 53, 15 (28%) female

  • Mean age, years: 26.36

  • Age range, years: 9 to 47

Control group: n = 53, 15 (28%) female

  • Mean age, years: 26.41

  • Age range, years: 9 to 47

Asthma diagnosis: satisfying the clinical criteria of Crotton, Douglas and Shivpuri
Inclusion criteria: established bronchial asthma
Exclusion criteria: not recorded

Interventions

Active treatment:

  • Training programme over 2 weeks with 2.5 hours daily. Included were breathing exercises associated with simple movements; yoga loosening exercises; various physical postures combined with slow breathing and exercise; relaxation and slow deep breathing; meditation and devotional session including chanting; weekly traditional voluntary nose and stomach wash techniques; yoga philosophy lectures and discussions

Participants were instructed to continue the practises daily during the follow-up period of 30 months
Control group: continued taking the usual drugs during the study. Participants in this group reported for checkups every 6 months
Co-intervention: no inhalers used; continued with usual, self-regulated bronchodilators and injections. The doctor decided whether a change in the 'brand' of drug was required
Participants kept diaries recording drug usage, number and severity of attacks of airway obstruction

OutcomesPulmonary function: PEF
Number and severity of attacks (1 = mild, but did not disturb sleep or daily routine; 2 = moderate, disturbed sleep and daily routine and relieved by oral drugs; 3 = severe, required injection or admission to hospital)
NotesWrote to author for clarification
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskThe method of sequence generation is not described
Allocation concealment (selection bias)Unclear riskThe method of concealment is not described
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskInsufficient information to permit judgement of ‘low risk’ or ‘high risk'
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskInsufficient information to permit judgement of ‘low risk’ or ‘high risk’
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskInsufficient reporting of attrition/exclusions to permit judgement of ‘low risk’ or 'high risk'
Selective reporting (reporting bias)Low riskPublished reports include all expected outcomes
Other biasUnclear risk

Insufficient information to assess whether an important risk of bias exists

Blinding of participants and personnel (performance bias)

Days off work

Prem 2013

Methods

Design: randomised controlled trial

Method of randomisation: participants assigned to three groups through block randomisation

Method of allocation concealment: allocation concealed by sequentially numbered, sealed, opaque envelopes

Outcome assessor blinding: participant parameters recorded before and after training for three months by a person blinded to allocation of the groups

Withdrawals/dropouts: 5 dropouts described

Participants

Country: India
Setting: conducted at an outpatient department of chest medicine
Health status: mild to moderate asthma
Three arms in this trial (Buteyko, Pranayama and control group). The three arms were included in the review
Total sample: 120 participants, 40 in each group
Mean age, years: 38 ± 13 (Buteyko group), 35 ± 13 (pranaiama group) and 41 ± 14 (control group)

Age range, years: 18 to 60s

Exclusion criteria: Participants were excluded if they had medical conditions that impaired the performance of breathing techniques, had a previous history of breathing retraining, were pregnant and non-compliant with exercise for more than 15% of study period

Interventions

Active treatment: 3 to 5 days with a session of 60 minutes each day. Participants were then followed up for three months and were instructed to practise the exercise for 15 minutes twice daily

Intervention group: Buteyko and Pranayama

Control group received no additional treatment

Outcomes

Quality of life (Asthma Quality of Life Questionnaire—AQLQ)

Asthma symptoms (Asthma Control Questionnaire—ACQ)

Pulmonary function test

NotesThe author responded to our request regarding asthma severity of participants and the values on AQLQ, ACQ and pulmonary function tests
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskParticipants were assigned to three groups through block randomisation
Allocation concealment (selection bias)Low riskThe method of allocation was concealed by sequentially numbered, sealed, opaque envelopes
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskInsufficient information to permit judgement of ‘low risk’ or ‘high risk'
Blinding of outcome assessment (detection bias)
All outcomes
Low riskAssessments were performed by a person blinded to allocation of the groups
Incomplete outcome data (attrition bias)
All outcomes
Low riskReasons for missing outcome data unlikely to be related to true outcome
Selective reporting (reporting bias)High riskOne or more outcomes of interest in the review are reported incompletely, so that they cannot be entered into a meta-analysis
Other biasLow riskThe study appears to be free of other sources of bias

Singh 2012

Methods

Design: randomised controlled trial

Method of randomisation: not described

Method of allocation concealment: not described

Outcome assessor blinding: not described

Withdrawals/dropouts: Four participants withdrew from the study

Participants

Country: India
Setting: department of physiology, University College of Medical Sciences

Health status: mild to moderate asthma
Two arms in this trial (yoga and control groups)
Total sample: 60 participants
Mean age: not described

Age range, years: 18 to 60
30 participants in each group

Exclusion criteria: Individuals with a history of an exacerbation or respiratory tract infection, current smokers, pregnant or lactating women and those with any other disorder were excluded

Interventions

Active treatment: Group 1 (yoga training group) and Group 2 (control group). Yoga sessions included Pranayama (30 to 35 minutes), asanas (10 minutes), meditation (10 minutes) and lifestyle modification for 5 to 6 days. Thereafter, participants were practicing yoga for an average of 40 to 50 minutes daily at home for 2 months

Control group received no additional treatment

Outcomes

Asthma quality of life (AQLQ)

Pulmonary function test

NotesWe have written to the author to ask for further clarification regarding total sample size and total score on the AQLQ
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskThe method of sequence generation is not described
Allocation concealment (selection bias)Unclear riskThe method of concealment is not described
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskInsufficient information to permit judgement of ‘low risk’ or ‘high risk'
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskInsufficient information to permit judgement of ‘low risk’ or ‘high risk’
Incomplete outcome data (attrition bias)
All outcomes
Low riskReasons for missing outcome data unlikely to be related to true outcome
Selective reporting (reporting bias)Low riskPublished reports include all expected outcomes
Other biasUnclear riskInsufficient information to assess whether an important risk of bias exists

Sodhi 2009

Methods

Design: randomised controlled trial over 8 weeks

Method of randomisation: not described

Method of allocation concealment: not described

Outcome assessor blinding: not described

Withdrawals/dropouts: not described

Participants

Country: India

Setting: Departments of Medicine and Physiology, Christian Medical College & Hospital

Health status: mild to moderate asthma

Mean age, years: 35.55 ± 10.62 (range 17 to 50 years) in the control group and 38.77 ± 9.92 years (range 20 to 50 years) in the intervention group

Gender: 37 males and 23 females (control group) and 34 males and 26 females (intervention group)

Total sample: 120 participants

Inclusion criteria: non-smokers in the age group of 17 to 50 years with mild to moderate asthma

Exclusion criteria: individuals with a history of tuberculosis, chronic obstructive airway disease (COPD), diabetes, renal failure, coronary artery disease and musculoskeletal chest deformities, respiratory tract infection within the previous 6 weeks and engagement in any regular exercise/training

Interventions

Intervention group: 45-minute yoga training sessions per week with a trained instructor, which included pranayamas (deep breathing exercises), kapalabhati (cleaning breath), bhastrika (rapid and deep respiratory movements), ujjayi (loud sound producing pranayama) and sukha purvaka pranayama (easy comfortable breathing). Participants were instructed to practise at home, 45 minutes twice daily, on all days of the week. Participants maintained a diary record of each day of the yoga practise

Control group: conventional treatment

Pulmonary function tests were performed on all participants at baseline and after 4 and 8 weeks

OutcomesSpirometry
NotesThe author responded to our request regarding control group treatment
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskThe method of sequence generation is not described
Allocation concealment (selection bias)Unclear riskThe method of concealment is not described
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskInsufficient information to permit judgement of ‘low risk’ or ‘high risk'
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskInsufficient information to permit judgement of ‘low risk’ or ‘high risk’
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskInsufficient information to permit judgement of ‘low risk’ or ‘high risk’
Selective reporting (reporting bias)Low riskThe study protocol is not available, but published reports include all expected outcomes
Other biasUnclear riskInsufficient information to assess whether an important risk of bias exists

Thomas 2003

Methods

Design: randomised controlled trial

Method of randomisation: Volunteers were randomly assigned by alphabetical numbering and use of random number tables for assignment to trial groups

Method of allocation concealment: A statistician supervised the random allocation.
Blinding: The assessor was blinded when marking the assessments. Participants could not be blinded to their treatment group as to whether they were attending for breathing exercise or asthma education

Withdrawals/dropouts: intervention group: One participant had an exacerbation of a non-respiratory illness. Control group: One participant had already completed a similar breathing training course. One died from a myocardial infarct between the one- and six-month assessments. Two participants failed to return the six-month questionnaire

Participants

Country: England, UK
Setting: semi-rural general practise
Participants: n = 33.

Age range, years: 17 to 65.

Mean age, years: 48.8 ± 10.9 (intervention group) and 48.9 ±15.6 (control group)
7 (21%) male participants
Breathing trial: n = 17
Control group: n = 16
Asthma diagnosis: Searches were made of medical notes of participants with a diagnosis of asthma made by a general practitioner and at least one prescription for an inhaled or oral bronchodilator or a prophylactic antiasthma medication in the previous year

InterventionsActive treatment: breathing retraining with a chartered physiotherapist. Initial group treatment for 45 minutes followed by two individual training sessions lasting 15 minutes each, which were 1 and 2 weeks apart. Explanation and training given in relaxed diaphragmatic breathing. Participants were assessed at 1 and 6 months post-intervention
Control group: 60-minute group session with asthma nurse teaching asthma education. Participants invited to attend for further individual asthma review if they wished
Outcomes

Quality of life measured by the Asthma Quality of Life Questionnaire (AQLQ)

Dysfunctional breathing measured by the Nijmegen Questionnaire

NotesThe author has responded with further information regarding non-parametric data, method of randomisation, etc
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskVolunteers were randomly assigned by alphabetical numbering and by use of random number tables for assignment to trial groups
Allocation concealment (selection bias)Unclear riskRandomisation was supervised by a statistician, but the paper does not fully describe the method of allocation concealment
Blinding of participants and personnel (performance bias)
All outcomes
High riskNo blinding of participants and personnel or of the outcome is likely to be influenced by lack of blinding
Blinding of outcome assessment (detection bias)
All outcomes
Low riskThe questionnaires were scored blinded by the investigator
Incomplete outcome data (attrition bias)
All outcomes
Low riskMissing outcome data were balanced in numbers across intervention groups, with similar reasons for missing data across groups
Selective reporting (reporting bias)Low riskPublished reports include all expected outcomes
Other biasLow riskThe study appears to be free of other sources of bias

Thomas 2009

Methods

Design: single-blind randomised controlled trial over three sessions

Method of randomisation: not described

Method of allocation concealment: not described

Outcome assessor blinding: Data entry and analysis were performed blind to randomisation status

Withdrawals/dropouts: 54 withdrawals (22 preintervention, 9 after intervention and before assessment; 23 did not return 6-month questionnaires)

Participants

Country: England, UK

Setting: not described

Health status: mild to moderate asthma

Mean age, years: 46.0 (35.0 to 57.0) (control group) and 46.0 (33.0 to 57.3) (intervention group)

Gender: 29 males and 60 females (control group) and 42 males and 52 females (intervention group)

Total sample: 183

Inclusion criteria: non-smokers, patients treated for asthma at 10 UK primary care general practises in Leicester, UK, and having moderate impairment of asthma-related health status (Asthma Quality of Life Questionnaire score < 5.5)

Interventions

Both groups consisted of an initial 60-minute small group session (2 to 4 participants) followed by two individual sessions of 30 to 45 minutes with 2 to 4 weeks between attendances

Breathing training group received explanation of normal breathing and possible effects of abnormal 'dysfunctional breathing'. During individual sessions, participants were taught diaphragmatic and nasal breathing techniques and were encouraged to practise these exercises for at least 10 minutes each day

Control group received three sessions of nurse-provided asthma education

Outcomes

Quality of life measured by the Asthma Quality of Life Questionnaire (AQLQ)

Asthma control assessed by the Asthma Control Questionnaire (ACQ) and asthma symptoms measured by the Nijmegen Hyperventilation Questionnaire (NQ)

Hospital Anxiety and Depression Score (HADS)

Spirometry

Capnography

NotesThe author has responded to our enquiries with further details
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskThe method of sequence generation was not described
Allocation concealment (selection bias)Unclear riskThe method of concealment was not described
Blinding of participants and personnel (performance bias)
All outcomes
High riskNo blinding of participants and personnel, and the outcome is likely to be influenced by lack of blinding
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskInsufficient information to permit judgement of ‘low risk’ or ‘high risk’
Incomplete outcome data (attrition bias)
All outcomes
Low riskMissing outcome data balanced in numbers across intervention groups with similar reasons for missing data across groups
Selective reporting (reporting bias)Low riskThe study protocol is not available, but the published reports include all expected outcomes
Other biasUnclear riskInsufficient information to assess whether an important risk of bias exists

Vedanthan 1998

Methods

Design: randomised controlled trial over three weeks

Method of randomisation: not described

Outcome assessor blinding: assessor unaware of data from active and control groups

Withdrawals/dropouts: All participants completed the study, and no withdrawals or dropouts were reported

Participants

Country: USA

Setting: University, Allergy and Asthma Clinic. Health Centre

Provider: yoga teacher

Randomly assigned participants: 17 students

  • Age range, years: 19 to 52

  • Mean age, years: 26.5

Yoga trial participants: n = 9, 3 (33%) female

  • Mean age, years: 28.12

Controls: n = 8, 6 (75%) female

  • Mean age, years: 25.11

Asthma diagnosis: based on guidelines established by the National Asthma Education Panel
Recruitment: student volunteers from a university asthma and allergy clinic
Inclusion criteria: mild to moderate asthma
Exclusion criteria: not stated
No smokers in either group
Adverse effects: none reported

InterventionsActive treatment: training programme of yoga techniques, including various breath-slowing exercises together with physical exercises; these were performed without breath holding: also physical postures, meditation, exercises and lectures on yoga philosophy
Participants given audio cassettes and written information for home practise
Duration: 45 minutes, 3 times a week for 16 weeks
Control group: no information given
Both groups were given peak flow meters to record daily am and pm readings
Participants from both groups regularly attended the Health Center
OutcomesPulmonary function tests
Symptom questionnaire, which included severity and frequency of attack scores
NotesThe author has responded to our enquiries with further details
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskThe method of sequence generation is not described
Allocation concealment (selection bias)Unclear riskThe method of concealment is not described
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskInsufficient information to permit judgement of ‘low risk’ or ‘high risk'
Blinding of outcome assessment (detection bias)
All outcomes
Low riskDecoded data were unavailable to the principal investigators
Incomplete outcome data (attrition bias)
All outcomes
Low riskNo dropouts reported
Selective reporting (reporting bias)High riskOne or more outcomes of interest in the review are reported incompletely, so they cannot be entered into a meta-analysis
Other biasUnclear riskInsufficient information to assess whether an important risk of bias exists

Vempati 2009

Methods

Design: randomised controlled trial over 8 weeks

Method of randomisation: not described

Method of allocation concealment: not described

Outcome assessor blinding: not described

Withdrawals/dropouts: One participant in the yoga group, and two participants in the control group discontinued the study

Participants

Country: India

Setting: Integral Health Clinic, All India Institute of Medical Sciences (2 weeks) and intervention at home (6 weeks)

Health status: mild to moderate asthma

Mean age, years: 33.4 ± 11.5 (control group) and 33.5 ± 11.4 (intervention group)

Gender: 20 males and 8 females (control group) and 13 males and 16 females (intervention group)

Total sample: 57 participants

Inclusion criteria: age 18 years or older; an established diagnosis of mild to moderate asthma for at least 6 months (meeting American Thoracic Society spirometry criteria for mild to moderate asthma; taking at least one of the following: inhaled β-agonists, methyl-methylxanthines, anticholinergics, inhaled corticosteroids; and stable medication dosing for the past month

Exclusion criteria: individuals who smoked currently (or in the past year) or had a smoking history of greater than 5 pack-years; had a concomitant lung disease; were taking leukotriene inhibitors or receptor antagonists, or mast cell–stabilising agents for at least 6 months; practised yoga or any other similar discipline during 6 months preceding the study; were pregnant; had a chronic medical condition that required treatment with oral or systemic corticosteroids in the past month; had a medical condition that contraindicated exercise; or had an unstable medical condition

Interventions

Intervention: Yoga group underwent a yoga-based lifestyle modification and stress management programme for 4 hours a day over 2 weeks and an additional 6 weeks of home practise. The programme consisted of lectures and practical sessions on asanas (postures), pranayamas (breathing techniques), kriyas (cleansing techniques), meditation and shavasana (a relaxation technique)

Control group: conventional care

Outcome measures were performed on all participants at baseline and after 2, 4 and 8 weeks

Outcomes

Quality of life as measured by the Asthma Quality of Life Questionnaire (AQLQ)

Pulmonary function

NotesN/A
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskThe method of sequence generation is not described
Allocation concealment (selection bias)Unclear riskThe method of concealment is not described
Blinding of participants and personnel (performance bias)
All outcomes
High riskNo blinding of participants and personnel, and the outcome is likely to be influenced by lack of blinding
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskInsufficient information to permit judgement of ‘low risk’ or ‘high risk
Incomplete outcome data (attrition bias)
All outcomes
Low riskMissing outcome data were balanced in numbers across intervention groups
Selective reporting (reporting bias)Low riskThe study protocol is available, and all of the study’s prespecified (primary and secondary) outcomes that are of interest in the review have been reported in the prespecified way
Other biasUnclear riskInsufficient information to assess whether an important risk of bias exists

Characteristics of excluded studies [ordered by study ID]

StudyReason for exclusion
Aleksandrov 1990Not a randomised controlled trial (RCT)
Anonymous 1968Investigation comparing the active group treated with hypnosis and the control group treated with breathing plus relaxation training
Asher 1990Each treatment preceded by nebulised salbutamol. Multiple intervention treatments
Berlowitz 1995Not an RCT
Bobokhodzhaev 1984Not an RCT
Bowler 1998The control group was given relaxation techniques
Cambach 1997Mixed population of chronic obstructive pulmonary disease (COPD) and asthma in programme
Multiple interventions
Cambach 1999Not an RCT
Coll 1994Journal letter only. Not an RCT
Cooper 2003Device used
Cowie 2008Comparison between Buteyko and chest physiotherapy. No control group
Emtner 1998Not an RCT. Three studies included in dissertation. Physical training principal component in all studies
Erskine 1979No breathing training. Comparison of muscular relaxation with muscular and mental relaxation training in participants with asthma. No control group
Falkenbach 1993Not an RCT. Participants acted as their own control in a before-after trial. A control group was not established for satisfactory statistical analyses because of the small numbers involved
Gallefoss 1999Breathing training not a major component of the physiotherapy intervention
Gosselink 1993Not an RCT
Holmes 1990Not an RCT
Joseph 1999Not an RCT
Khanam 1996Not an RCT
Kotses 1978No breathing training. Examining muscle tension relationships with bronchial airways resistance
Kurabayashi 1998Not an RCT, no control group, COPD not asthma
Lacasse 1997Not an RCT
Loew 1996Not RCT. Comparison of the effects of treatment with terbutaline and relaxation. Breathing plus movement therapy in two groups of asthmatic participants
Manocha 2002Breathing retraining not included as part of intervention
Mass 1991Device used for breathing training
McFadden 1986Not a study of breathing exercises. Study was set up to observe thermal effects on the airways in exercise-induced asthma
McHugh 2003The control group was given relaxation techniques
Mussell 1986Device used for reducing bronchospasm
Opat 2000The control group was given a placebo video  
Paleev 1988Not an RCT
Pryor 1979Thesis. Treatments randomly assigned, not participants. Evaluation of postural drainage time for evacuation of secretions with and without the addition of forced expiratory technique (FET), in addition to other physiotherapeutic modalities
Redchits 1986Not an RCT
Sabina 2005Comparison between yoga and stretching. No control group
Saxena 2009Comparison between yoga and meditation. No control group
Schulze 2000

Not an RCT

Children

Shaw 2011Device used for diaphragmatic breathing training
Singh 1987Excluded. A device was used to alter the breathing pattern. Description of device amended in 2003 update in response to researcher's comment that the device does not increase muscle strength but imposes components of pranayamic breathing
Singh 1990Device used
Slader 2006Comparison of two breathing techniques. No control group
Smyth 1999Not an RCT. Relaxation training, not breathing, as principal component
Tandon 1978Study involved participants with COPD, not asthma
van der Schans 1997No breathing exercises. Study used propranolol to induce bronchoconstriction and then reversed its effect using pursed-lip breathing
Weiner 1992Device used
Wilson 1975Transcendental meditation, not breathing training

Characteristics of ongoing studies [ordered by study ID]

Murthy 2010

Trial name or titleEffect of naturopathy interventions in bronchial asthma 
Methods

Design: randomised wait-listed control clinical study

Method of randomisation: computer-generated randomisation

Method of allocation concealment: open list of random numbers

Blinding/masking: not applicable

ParticipantsIndividuals aged 18 to 65 years, with mild to moderate persistent asthma; non-smokers/stopped smoking 6 months back
InterventionsIntervention: naturopathy and yoga interventions
Control Intervention: waiting list control
Outcomes

Primary outcomes

  • Nyugen asthma severity index

  • Juniper asthma quality of life

  • Asthma control score

Secondary outcomes

  • Lung function

  • Perceived control of asthma questionnaire

  • Asthma diary

  • Epworth daytime sleepiness scale

Starting date01/10/2009 (date of first enrolment)
Contact informationINYS-Medical Research Society. Jindal Nagar
NotesN/A

Thomas 2011

Trial name or titleStudy of the effectiveness of breathing training exercises taught by a physiotherapist by instructional videos/DVDs/Internet download or by face-to-face sessions in the management of asthma in adults
Methods

Design: pragmatic observer-blinded three-arm parallel-group randomised controlled trial

Method of randomisation: not described

Method of allocation concealment: not described

Participants

Inclusion criteria

  • Full practise registration for a minimum of 12 months before enrolment

  • Age 16 to 70 years

  • Physician-diagnosed asthma in medical records

  • One or more antiasthma medication prescriptions in the previous year (determined from physician prescribing records)

  • Impaired asthma-related health status (Asthma Quality of Life Questionnaire score < 5.5)

  • Informed consent

Exclusion criteria

  • Asthma judged at the baseline assessment not to be dangerously unstable and in need of urgent medical review

  • Documented diagnosis of chronic obstructive pulmonary disease (COPD)

Interventions

Three arms included in the trial

  • Receipt of the DVD, the video or the Internet download (plus supporting written material, according to preference)

  • Three sessions (arranged at fortnightly intervals) of face-to-face physiotherapy breathing instruction

  • Usual care

Outcomes

Primary outcome

  • Analysis of between-group (intention-to-treat (ITT)) change in asthma-specific health status (AQLQ (short version) score)

Secondary outcomes

  • Asthma Control Questionnaire score

  • Lung function

  • Fraction of exhaled nitric oxide

  • Health status (EuroQOL)

  • Anxiety and depression scores (HAD questionnaire)

  • Hyperventilation (Nijmegen questionnaire)

  • Oral corticosteroid courses

  • Bronchodilator use

  • Asthma-related health resource use

  • Smoking status

  • Cost-effectiveness/utility

  • Participant-reported process evaluations (questionnaires) and estimates of adherence (use of exercises)

Starting date01/11/2011
Contact informationGeneral Practice and Primary Care
University of Aberdeen
Centre of Academic and Primary Care
NotesN/A

Ancillary