Exercise training to improve exercise capacity and quality of life in people with non-malignant dust-related respiratory diseases

Our plain-English summary of Exercise training to improve exercise capacity and quality of life in people with non-malignant dust-related respiratory diseases, by M.T. Dale, Z.J. McKeough, T. Troosters, et al (The Cochrane Database of Systematic Reviews, 2015).

The study

• Authors: M.T. Dale, Z.J. McKeough, T. Troosters, P. Bye, J.A. Alison
• Journal: The Cochrane Database of Systematic Reviews
• Published: 2015;2015(11):CD009385
• Type of article: Meta-analysis, Systematic review
• Cited by: 13 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Non-malignant dust-related respiratory diseases, such as asbestosis and silicosis, are similar to other chronic respiratory diseases and may be characterised by breathlessness, reduced exercise capacity and reduced health-related quality of life. Some non-malignant dust-related respiratory diseases are a global health issue and very few treatment options, including pharmacological, are available. Therefore, examining the role of exercise training is particularly important to determine whether exercise training is an effective treatment option in non-malignant dust-related respiratory diseases.

Objectives: To assess the effects of exercise training for people with non-malignant dust-related respiratory diseases compared with control, placebo or another non-exercise intervention on exercise capacity, health-related quality of life and levels of physical activity.

Search Methods: We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE/PubMed, EMBASE, CINAHL, PEDro and AMED (all searched from inception until February 2015), national and international clinical trial registries, reference lists of relevant papers and we contacted experts in the field for identification of suitable studies.

Selection Criteria: We included only randomised controlled trials (RCTs) that compared exercise training of at least four weeks duration with no exercise training, placebo or another non-exercise intervention.

Data Collection And Analysis: We used standard methodological procedures expected by Cochrane. Two review authors independently assessed study eligibility and risk of bias, and extracted data. We employed the GRADE approach to assess the overall quality of evidence for each outcome and to interpret findings. We synthesized study results using a random-effects model based on the assessment of heterogeneity. We conducted subgroup analyses on participants with dust-related interstitial lung diseases (ILDs) and participants with asbestos related pleural disease (ARPD).

Main Results: Two RCTs including a combined total of 40 participants (35 from one study and five from a second study) met the inclusion criteria. Twenty-one participants were randomised to the exercise training group and 19 participants were randomised to the control group. The included studies evaluated the effects of exercise training compared to a control group of no exercise training in people with dust-related ILDs and ARPD. The exercise training programme in both studies was in an outpatient setting for an eight-week period. The risk of bias was low in both studies. There were no reported adverse events of exercise training. Following exercise training, six-minute walk distance (6MWD) increased with a mean difference (MD) of 53.81 metres (m) (95% CI 34.36 to 73.26 m). Improvements were also seen in the domains of health-related quality of life: Chronic Respiratory Disease Questionnaire (CRQ) Dyspnoea domain (MD 2.58, 95% CI 0.72 to 4.44); CRQ Fatigue domain (MD 1.00, 95% CI 0.11 to 1.89); CRQ Emotional Function domain (MD 2.61, 95% CI 0.74 to 4.49); and CRQ Mastery domain (MD 1.51, 95% CI 0.29 to 2.72). Improvements in exercise capacity and health-related quality of life were also evident six months following the intervention period: 6MWD (MD 52.68 m, 95% CI 27.43 to 77.93 m); CRQ Dyspnoea domain (MD 3.03, 95% CI 1.41 to 4.66); CRQ Emotional Function domain (MD 5.57, 95% CI 2.34 to 8.81); and CRQ Mastery domain (MD 2.66, 95% CI 1.08 to 4.23). Exercise training did not result in improvements in the Modified Medical Research Council (MMRC) dyspnoea scale immediately following exercise training or six months following exercise training. The improvements following exercise training were similar in a subgroup of participants with dust-related ILDs and in a subgroup of participants with ARPD compared to the control group, with no statistically significant differences in treatment effects between the subgroups.

Authors' Conclusions: The evidence examining exercise training in people with non-malignant dust-related respiratory diseases is of very low quality. This is due to imprecision in the results from the small number of trials and the small number of participants, the indirectness of evidence due to a paucity of information on disease severity and the data from one study being from a subgroup of participants, and inconsistency from high heterogeneity in some results. Therefore, although the review findings indicate that an exercise training programme is effective in improving exercise capacity and health-related quality of life in the short-term and at six months follow-up, we remain unsure of these findings due to the very low quality evidence. Larger, high quality trials are needed to determine the strength of these findings.

In plain English

This Cochrane systematic review looked for randomised trials of exercise training in people with non-malignant dust-related respiratory diseases such as asbestosis and silicosis. Two Australian trials met its criteria, with 40 men aged 55 to 86. Of these, 21 did outpatient exercise training two or three times a week for eight weeks and 19 did not. Combining both trials, the exercise group walked 53.81 metres further than controls in a six-minute walk test right after training (95% CI 34.36 to 73.26). Six months later the difference was 52.68 metres (95% CI 27.43 to 77.93). Quality-of-life scores improved in all four questionnaire areas right after training and in three of four at six months, but the authors called their clinical importance unclear. Breathlessness on a separate scale and lung function did not change significantly, and no harms were reported. Results were similar in people with dust-related interstitial lung disease and in those with asbestos related pleural disease. The authors rated all the evidence very low quality and said they remained unsure of the findings. Four of the five review authors had run one of the two trials.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Cochrane systematic review with meta-analysis of randomised controlled trials comparing exercise training (at least four weeks) with no exercise training, placebo or another non-exercise intervention
• Who was studied: Two parallel randomised trials conducted in Australia (Dale 2014, 35 participants; Holland 2008, 5 participants with asbestosis drawn from a larger group with mixed interstitial lung diseases), 40 participants in total. All were men aged 55 to 86. In Dale 2014, 24 had asbestos related pleural disease, 5 asbestosis, 2 combined asbestosis and asbestos related pleural disease, 3 silicosis and 1 mixed-dust pneumoconiosis. 21 were randomised to exercise training and 19 to control.
• Exposure: Participants had non-malignant diseases caused by inhaled dust (asbestosis, silicosis, mixed-dust pneumoconiosis, asbestos related pleural disease). The intervention studied was supervised outpatient exercise training two or three times a week for eight weeks: aerobic training (cycling and walking) in Dale 2014, and aerobic plus resistance training in Holland 2008. It was compared with usual care (Dale 2014) or weekly telephone calls giving general health advice (Holland 2008).
• Main results:
  • Immediately after training, six-minute walk distance improved in the exercise group compared with controls: mean difference 53.81 metres (95% CI 34.36 to 73.26 m), both trials combined.
  • Six months after the training period, the improvement in six-minute walk distance was maintained: mean difference 52.68 metres (95% CI 27.43 to 77.93 m).
  • Immediately after training, all four Chronic Respiratory Disease Questionnaire (CRQ) quality-of-life domains improved in the exercise group compared with controls: Dyspnoea MD 2.58 (95% CI 0.72 to 4.44), Fatigue MD 1.00 (0.11 to 1.89), Emotional Function MD 2.61 (0.74 to 4.49), Mastery MD 1.51 (0.29 to 2.72).
  • At six months, CRQ Dyspnoea (MD 3.03, 95% CI 1.41 to 4.66), Emotional Function (MD 5.57, 95% CI 2.34 to 8.81) and Mastery (MD 2.66, 95% CI 1.08 to 4.23) remained improved in the exercise group compared with controls.
  • At six months, CRQ Fatigue was not improved: MD 2.51 (95% CI -0.41 to 5.42).
  • Peak work rate on a cycle test did not improve immediately after training: MD 9.54 watts (95% CI -0.38 to 19.47).
  • There were no significant changes in dyspnoea on the MMRC scale (MD -0.29, 95% CI -0.81 to 0.23 immediately; MD -0.56, 95% CI -1.43 to 0.31 at six months). Lung function at six months (FVC and FEV1) also did not change significantly.
  • Neither trial reported adverse events from exercise training.
  • Improvements were similar in the subgroup with dust-related interstitial lung disease and in the subgroup with asbestos related pleural disease, with no statistically significant differences in treatment effect between them. Data for asbestos related pleural disease came from one trial only.
• The authors' conclusion: The authors concluded that the evidence was of very low quality. The findings indicate that exercise training improves exercise capacity and health-related quality of life in the short term and at six months, but the authors remained unsure of these findings and called for larger, high quality trials.
• Limitations the authors state:
  • The evidence comes from only two studies with 40 people.
  • Neither trial reported participants' disease severity.
  • The data used from Holland 2008 were from a subgroup of that trial's participants.
  • Only one trial included people with asbestos related pleural disease.
  • No threshold for a meaningful change in quality of life has been set for people with dust-related diseases. The CRQ questionnaire was not developed for these diseases. For these reasons, the authors said the clinical significance of the quality-of-life improvements remains unclear.
  • Four of the five review authors conducted one of the two included trials (a potential conflict of interest). To limit this, another review author and a person unrelated to the review checked that trial's eligibility.

Topics

Medical terms in this study, explained in our Lexicon: Quality of Life, Silicosis, Clinical Trial, Interstitial Lung Disease, Six-Minute Walk Test.

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