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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].

The 6-minute walk test in outpatient cardiac rehabilitation: validity, reliability and responsiveness: a systematic review

RN Bellet, L Adams, and NR Morris.

Review published: 2012.

Link to full article: [Journal publisher]

CRD summary

The authors concluded that strong evidence suggested the 6-minute walk test was responsive to clinical change in patients following cardiac rehabilitation. This conclusion reflects the evidence presented, but possible error and bias in the review process, with questions about the validity of the quality assessment tool limits any conclusive judgement about the reliability of the review.

Authors' objectives

To examine the validity, reliability and responsiveness of the 6-minute walk test in patients undergoing outpatient cardiac rehabilitation.

Searching

MEDLINE, CINAHL, EMBASE, SPORTDiscus and The Cochrane Library were searched from 1948 to 2011 for articles published in English. The reference lists of included articles were scanned to identify further studies.

Study selection

Eligible for inclusion were full-text articles of trials and observational studies that compared the 6-minute walk test with an established reference test in people with coronary artery disease, before and after participating in outpatient cardiac rehabilitation.

The included studies varied in study design, and comprised men and women with a mean age between 52 and 76 years (where reported). Different protocols for the 6-minute walk test were reported. Many studies included the cycle exercise test as the gold standard reference test.

One reviewer selected the studies for inclusion in the review.

Assessment of study quality

Study quality was assessed using a tool developed from three established sets of criteria. Studies that scored over 60% positive responses were considered high quality; studies that scored less than 40% were low quality.

Two reviewers assessed study quality, and disagreements were resolved by consensus.

Data extraction

Data were extracted to enable conversion to mean differences and standard error. Correlations, percentage change and effect sizes were also presented.

Data were extracted by one reviewer, and checked by a second reviewer.

Methods of synthesis

Where possible, studies were combined in a random-effects meta-analysis. Statistical heterogeneity was quantified using Ι². Other synthesis was narrative.

Results of the review

Fifteen studies were included in the review. Of these, two studies assessed reliability (nine and 94 participants; one was high quality); eight assessed validity (sample size range 10 to 630; six were high quality); and 12 assessed responsiveness (sample size range 18 to 982; 11 were high quality).

Meta-analysis revealed strong evidence on responsiveness of the 6-minute walk test to changes in the clinical status of participants following cardiac rehabilitation. Results revealed an estimated mean difference in 6-minute walk distance of 60.43m (95% CI 54.57 to 66.30 metres; 14 studies; Ι²=60%) and this was statistically significant (p<0.001). The median effect size was 0.65.

There was moderate evidence to demonstrate the reliability of the 6-minute walk test, with an intra-class correlation coefficient of 0.97 and a 2% to 8% test-retest change (two studies). Moderate evidence was found for validity of the test, with correlations ranging from 0.56 to 0.93 in relation to maximum power, oxygen uptake and maximum metabolic equivalents during symptom-limited exercise tests. Two moderate/high quality studies found positive relationships between the test and peak heart rate at the ventilatory threshold during cycle exercise. Two of three moderate/high quality studies found moderate correlations (ranging from 0.54 to 0.62) between the 6-minute walking test and health and function outcomes, when quality-of-life questionnaires were used as reference tests. Other results for test validity were limited or inconclusive.

Further results on the discriminative ability of the test were reported in the paper.

Authors' conclusions

Strong evidence suggests that the 6-minute walk test was responsive to clinical change following cardiac rehabilitation.

CRD commentary

The review question was clear. Inclusion criteria were adequately specified. Relevant data sources were accessed, but the restriction to articles published in English may have led to studies being overlooked, and the associated biases with these restrictions could not be ruled out. The review process did not appear to contain sufficient efforts to minimise error and bias for study selection.

The adapted quality assessment tool appeared to be appropriate, but justification for thresholds denoting high and low quality was not fully explained. The use of different methods of synthesis appeared appropriate, given the clinical heterogeneity presented in the study details. Statistical heterogeneity was quantified, where appropriate.

The authors' conclusion reflects the evidence presented, but possible error and bias in the selection of studies and questions about the validity of the quality assessment tool (acknowledged by the authors) limits any conclusive judgement about the reliability of the review.

Implications of the review for practice and research

Practice: The authors stated that the 6-minute walk test was suitable for outcome assessment before and after cardiac rehabilitation.

Research: The authors stated that future research should focus on the intra- and inter-tester reliability of the 6-minute walk test, assess the validity of the test against treadmill exercise tests and explore the prognostic and predictive value of 6-minute walking distances in patients undergoing cardiac rehabilitation.

Funding

Queensland Health Community Rehabilitation Workforce Project: Community Rehabilitation Research Scheme.

Bibliographic details

Bellet RN, Adams L, Morris NR. The 6-minute walk test in outpatient cardiac rehabilitation: validity, reliability and responsiveness: a systematic review. Physiotherapy 2012; 98(4): 277-286. [PubMed: 23122432]

Indexing Status

Subject indexing assigned by NLM

MeSH

Ambulatory Care /standards; Coronary Artery Disease /rehabilitation; Exercise Test /standards; Humans; Physical Therapy Modalities /standards; Reproducibility of Results; Walking

AccessionNumber

12012055735

Database entry date

03/05/2013

Record Status

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

CRD has determined that this article meets the DARE scientific quality criteria for a systematic review.

Copyright © 2014 University of York.

PMID: 23122432

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