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Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet]. York (UK): Centre for Reviews and Dissemination (UK); 1995-.
Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet].
Show detailsAuthors' objectives
To establish the influence and effect size of respiratory rehabilitation on functional exercise capacity, maximum exercise capacity and health-related quality of life in patients with chronic obstructive pulmonary disease (COPD).
Searching
MEDLINE was searched from 1966 until October 1995 and CINAHL was searched from 1982 until October 1995 for articles published in any language. The search terms used were: ('lung diseases, obstructive'), ('rehabilitation' or 'exercise therapy'), and ('research design' or 'longitudinal studies' or 'evaluation study' or 'randomized controlled trials'). Reference list of relevant articles were reviewed and abstracts presented at international meetings (American Thoracic Society, 1980-1995, European Respiratory Society, 1987-1994) were searched. Investigators of studies included in the review were contacted to locate unpublished studies.
Study selection
Study designs of evaluations included in the review
Randomised controlled trials (RCTs) comparing respiratory rehabilitation with conventional community care or with any other intervention unlikely to have an effect on exercise capacity or quality of life. The trials had to be of least 4 weeks' duration, and ranged from 6 weeks to 6 months, with one trial being of continuous duration.
Specific interventions included in the review
Any in-patient, out-patient or home-based rehabilitation programme of at least four weeks' duration that included exercise therapy (with or without any form of education), psychological support for patients with exercise limitation attributable to COPD or both. The interventions included in the studies were lower-limb exercises, upper limb exercises, inspiratory-muscle training, breathing exercises, postural drainage. The setting was home-based for five trials, outpatient for six trials and inpatient for two trials.
Participants included in the review
Trials were accepted in which more than 90% of patients had a clinical diagnosis of COPD and either a best recorded ratio of forced expiratory volume in 1 second(s) (FEV1) to forced vital capacity (FVC) of less than 0.7, or a best reported FEV1 of less than 70% of the predicted value. Most of the patients in the included studies were elderly and had severe COPD. The main exclusion criteria in the included studies were: ischaemic heart disease, heart failure, intermittent claudication, disabling musculoskeletal disorders, domicillary oxygen requirements, hypercapnia and other medical disorders that limited exercise tolerance.
Outcomes assessed in the review
Maximum or functional exercise capacity and health-related quality of life (HRQL) were assessed.
How were decisions on the relevance of primary studies made?
Two reviewers abstracted the data. The reviewers disagreed about two reports but both were included after discussion with a third reviewer.
Assessment of study quality
The authors examined the randomisation process and outcome assessment. When these were not detailed in the original trial publication, the investigators were contacted for clarification. For the meta-analysis of HRQL, only instruments for which there was evidence of validity were included. Two reviewers abstracted the data.
Data extraction
Two reviewers abstracted the data from the papers. Investigators were requested to provide missing data and to provide a copy of the questionnaire used to measure HRQL. Sample size was defined as the number of participants at study completion (i.e. not an intention-to-treat analysis).
Methods of synthesis
How were the studies combined?
The studies were combined by weighted mean difference using a random-effects model. The pooled effects sizes and corresponding 95% confidence intervals (CI) were reported for each outcome in standard deviation (SD) units and then converted back to natural units. Where possible, the minimum clinically important difference (MCID) - defined as the smallest difference perceived by the average patient - was compared with the overall treatment effect.
How were differences between studies investigated?
Homogeneity among study results was tested. Subgroup analysis was performed when significant heterogeneity was found in the primary findings of the trials, or when the CI for the overall effect encompassed the MCID. Three respiratory disease physicians a priori identified possible sources of heterogeneity which were: disease severity, the comprehensiveness of the rehabilitation programme, the duration of the trials (short-term was defined as < 8 weeks) and setting (inpatient/outpatient versus home-based). Also assessed was the quality of the methods used among the outcomes of exercise capacity and HRQL.
Results of the review
Sixteen trials were included in the review and 14 trials were included in the meta-analysis, with a total of 478 patients. Maximum exercise capacity was measured in 11 trials (309 patients), functional exercise capacity was measured in 11 trials (413 patients) and HRQL was measured using a valid instrument in 6 trials (number of patients not stated).
Maximum exercise capacity:
Pooled effect size was statistically-significant (0.3 SD units, 95% CI: 0.1, 0.6) which corresponded, in incremental cycle ergometer test units, to 8.3 W (95% CI: 2.8, 16.5). Test for heterogeneity was not statistically-significant (p=0.85).
Functional exercise capacity:
Converting back to natural units for the 6-minute walk test (metre 'm'), the difference in response between the treatment and control group was 55.7 m (95% CI: 27.8, 92.8). The limits of the confidence intervals (27.8 to 92.8) were wider than the estimated MCID (37-71m). There was significant heterogeneity among study results (p=0.0008) that could not be explained by subgroup analysis. Post hoc analysis showed a significant difference between programmes of 6 months' duration and the other programme (93m vs 39.2m; difference, p=0.0004).
Health related quality of life (HRQL):
For dyspnoea (breathing difficulty) and mastery, the overall treatment effect size was larger than the MCID:1.0 (95% CI:0.6,1.5) and 0.8 (95% CI:0.5, 1.2) respectively, compared with a MCID of 0.5.
Authors' conclusions
Respiratory rehabilitation relieves dyspnoea and improves control over COPD. These improvements are clinically important. The value of the improvement in exercise capacity is not clear. Respiratory rehabilitation is an effective part of care in patients with COPD.
CRD commentary
This is a thorough review with clear inclusion criteria and appropriate synthesis of results. Furthermore, the authors contacted investigators for missing data and in an attempt to locate unpublished data. Possible sources of heterogeneity were investigated by sensitivity and subgroup analysis. As the authors report, even though the rehabilitation programmes differed in several ways, the homogeneity in the results suggest that less sophisticated rehabilitation programmes may be as effective as more comprehensive programmes in improving HQRL.
Bibliographic details
Lacasse Y, Wong E, Guyatt G H, King D, Cook D J, Goldstein R S. Meta-analysis of respiratory rehabilitation in chronic obstructive pulmonary disease. Lancet 1996; 348: 1115-1119. [PubMed: 8888163]
Other publications of related interest
Rees PJ. Meta-analysis: respiratory rehabilitation relieves dyspnea in COPD. ACP J Club 1997;126:38.
Indexing Status
Subject indexing assigned by NLM
MeSH
Exercise Therapy; Humans; Lung Diseases, Obstructive /rehabilitation; Quality of Life; Randomized Controlled Trials as Topic; Treatment Outcome
AccessionNumber
Database entry date
30/11/1998
Record Status
This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.
- Meta-analysis of respiratory rehabilitation in chronic obstructive pulmonary dis...Meta-analysis of respiratory rehabilitation in chronic obstructive pulmonary disease - Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews
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