Interventions for promoting physical activity in people with COPD
Abstract
This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:
To evaluate the effectiveness of interventions to promote physical activity in people with chronic obstructive pulmonary disease (COPD).
Background
Description of the condition
Chronic obstructive pulmonary disease (COPD) is a common, treatable but incurable obstructive lung disease defined by persistent airflow limitation. Diagnosis is determined by spirometry in the clinical context of a person presenting with dyspnoea, chronic cough or sputum production, and a history of risk factor exposure (GOLD 2017). Development of COPD is primarily attributable to an enhanced chronic inflammatory airway response to noxious particles or gases and is strongly linked to a history of smoking. However, there are a number of other risk factors including exposure to air pollution, occupational exposures, genetics, asthma, history of severe childhood respiratory infection and low socioeconomic status (GOLD 2017). Systemic effects, including systemic inflammation and muscle dysfunction, and comorbid conditions, including cardiovascular disease, anxiety and depression, are associated with COPD (Choudhury 2014). Prevalence estimates suggest that COPD affects upwards of 384 million people (Adeloye 2015), and is the third leading cause of death worldwide (WHO 2017). Associated with advancing age (Anton 2016), and in the context of the fastest rate of population growth occurring in people over 65 years of age (UN 2015), COPD poses a substantial and growing economic and social burden (GOLD 2017).
Description of the intervention
The term ‘physical activity’ is defined as any bodily movement produced by skeletal muscles that results in energy expenditure (Casperson 1985). It is a complex behaviour traditionally described according to type, intensity and duration, and incorporates a subset of undertakings including exercise, occupational and household activities. Public health promotion for regular participation in physical activity typically references a minimum 150 minutes per week of at least moderate intensity activity in bouts of greater than 10‐minutes duration as ‘sufficient’ for health benefits across the adult population (WHO 2010). These benefits include reduced risk of all‐cause mortality, coronary heart disease, hypertension, stroke, metabolic syndrome, type 2 diabetes and depression (Lee 2012).
Participation in regular physical activity is also endorsed for people with COPD (GOLD 2017). Inactivity is one of the main risk factors for development of cardiovascular, metabolic and musculoskeletal comorbid conditions in people with COPD, and is observed across the disease spectrum (Van Remoortel 2014). Recent studies show that physical activity is reduced in smokers prior to diagnosis (Furlanetto 2014), in people with a recent diagnosis and mild COPD before symptom onset (Johnson‐Warrington 2014), and is independent of other clinical characteristics including impaired exercise capacity (Fastenau 2013; Gagnon 2015; Van Remoortel 2013; Watz 2009). Physical activity participation is reduced compared to healthy peers (Pitta 2005; Vorrink 2011), and to people with other chronic conditions (Arne 2009). It is further compromised during and after hospitalisation for an acute exacerbation (Pitta 2006a), and with increasing disease severity (Shrikrishna 2012; Troosters 2010; Waschki 2015). In people with COPD, low levels of participation in physical activity have been independently associated with poor outcomes, including increased risk for hospitalisation and mortality (Garcia‐Aymerich 2006; Garcia‐Rio 2012; Vaes 2014; Waschki 2011).
Much attention has been given to the development of physical activity interventions that incorporate strategies specifically designed to promote the adoption and maintenance of active lifestyles in the general population (Marcus 2006). For the purposes of this Cochrane Review, an intervention is any approach used with the specific purpose of increasing objectively measured physical activity in people with COPD. Such interventions may be provided by a broad range of healthcare professionals and be delivered in a variety of ways (for example, face to face, via internet or telephone).
How the intervention might work
Evidence suggests that people with COPD avoid participation in physical activity due to the perception of breathlessness, resulting from inefficiencies related to gas trapping and lung hyperinflation. A vicious circle is perpetuated, where muscle deconditioning results from avoiding activities that involve physical exertion and exacerbate symptoms, further compromising physical capacity to engage in activity (O’Donnell 2014). It is theorised that targeted interventions may be able to interrupt this cycle and increase participation in physical activity at a range of intensities that are associated with health benefits. The dual role of physical inactivity as both a cause and consequence in chronic disease identifies physical activity as a potentially modifiable target that could affect health‐related quality of life and disease trajectory (Esteban 2010; Vaes 2014; Watz 2014). Whether improvements in physical activity can ameliorate these effects in COPD is unknown.
Many physical and physiological disease features also appear to influence participation in physical activity by people with COPD. However, the quality of association between such features, including lung function, systemic inflammation, body composition, co‐morbidities and psychosocial factors, and physical activity participation is variable (Gimeno‐Santos 2011). Additional considerations, including fatigue (Andersson 2015), balance (Iwakura 2016), and seasonal and environmental factors (Alahmari 2015; Sewell 2010), may also impact on physical activity participation in this group. The broad range of strategies considered to date to address physical inactivity in people with COPD (for instance, exercise training, nutritional interventions and behavioural strategies) reflects the complexity of this issue.
Increased physical activity has been associated with reduced rate of exacerbations (Esteban 2014), which highlights that targeting improvements in physical activity in people with COPD may be an important therapeutic goal (Langer 2016; Singh 2016). However, achieving consistent improvements in participation and strong evidence for the positive impact on health outcomes remain elusive.
Why it is important to do this review
Escalating awareness of the magnitude of the challenge posed by physical inactivity in COPD at all points in the disease course highlights the need for interventions to address the limited participation in physical activity by people with COPD. The widely accepted benefits of physical activity, coupled with the increasing availability of wearable monitoring devices to objectively measure participation, has led to a dramatic rise in the number and variety of studies that aim to improve physical activity levels in people with COPD. However, little is known about the relative effectiveness of interventions tested so far, partly attributable to the complexities of data analysis and challenge of rapidly evolving technology. Whether improvements in physical activity are accompanied by improved exercise capacity and health‐related quality of life is unknown. This Cochrane Review aims to evaluate the efficacy of existing interventions to increase physical activity in people with COPD and signpost directions for future work.
Objectives
To evaluate the effectiveness of interventions to promote physical activity in people with chronic obstructive pulmonary disease (COPD).
Methods
Criteria for considering studies for this review
Types of studies
All randomised controlled trials of interventions designed to increase participation in physical activity for people with COPD. We will only include studies that use objective measures for the assessment of physical activity, as previous consensus statements (Watz 2014), and systematic reviews (Dhillon 2015; Gimeno‐Santos 2011), have failed to identify subjective tools that accurately reflect daily physical activity in people with COPD.
We will include studies reported as full‐text articles, those published as abstract only and unpublished data. Physical activity may be either a primary or a secondary outcome of the study. As we expect most studies will examine behavioural interventions, we will not include crossover trials as it would be difficult to exclude carryover of intervention effects between periods.
Types of participants
We will include adults (18 years of age and over) with a diagnosis of COPD according to established criteria, regardless of disease severity. We will include studies that incorporate a mix of diagnostic groups only if we can obtain data on any of the review outcomes separately for people with COPD.
Types of interventions
We will include trials that objectively assess physical activity as an outcome. These trials may compare any intervention designed to increase physical activity with no/sham intervention, or may compare a targeted physical activity intervention in addition to another standard intervention common to both groups. Interventions may include, but are not limited to, exercise training, education programmes, activity counselling and self‐management strategies. These may be supervised or unsupervised interventions. The increased focus on physical activity as an outcome of interest for pulmonary rehabilitation, Spruit 2013, has led to some studies considering its efficacy as an intervention to increase physical activity. Studies including objective assessment of physical activity will therefore be eligible for inclusion in this Cochrane Review. We will also include studies in which both groups received pulmonary rehabilitation (as defined by McCarthy 2015) and the inclusion of an additional specific physical activity intervention in one group is assessed.
Comparisons
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One or more interventions to increase physical activity vs no intervention
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One or more interventions to increase physical activity vs sham intervention
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One or more interventions to increase physical activity in addition to a standard intervention common to both groups
We will analyse studies that include pulmonary rehabilitation separately from studies that do not include pulmonary rehabilitation.
Types of outcome measures
Primary outcomes
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Studies must include variable(s) that reflect participation in physical activity, as measured objectively using a pedometer, accelerometer or activity monitor. Outcomes of interest include, but are not limited to step count, activity counts, energy expenditure and physical activity time (different intensities, range of thresholds used). Primary time points will be at baseline (prior to commencement) and at the time of intervention completion; we will use change in physical activity from baseline for analysis where possible. Additionally, we will categorise any follow‐up measurements reported following intervention completion as either short‐term (within one month), medium‐term (between one to six months) or long‐term (longer than 6 months). We will seek raw data from the study authors where possible to facilitate comparisons.
Secondary outcomes
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Health‐related quality of life (measured using either a generic or disease specific tool)
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Exercise capacity: measured using a laboratory or field exercise test e.g. cardiopulmonary exercise test, 6‐minute walk test
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Adverse events e.g. musculoskeletal injury
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Adherence to intervention
Search methods for identification of studies
Electronic searches
We will identify trials from the Cochrane Airways Group's Specialised Register (CAGR), which is maintained by the Information Specialist for the Cochrane Airways Group. The CAGR contains trial reports identified through systematic searches of bibliographic databases including the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, CINAHL, AMED, PsycINFO, PEDro (Physiotherapy Evidence Database), ClinicalTrials.gov (www.clinicaltrials.gov) and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) portal, as well as handsearching of respiratory journals and meeting abstracts (please see Appendix 1 for further details). We will search all records in the CAGR using the search strategy in Appendix 2.
We will also search of ClinicalTrials.gov (www.clinicaltrials.gov), the WHO ICTRP portal (www.who.int/ictrp/en/) and the Australia New Zealand Clinical Trials Registry (www.anzctr.org.au/). We will search all databases from their inception to the present, and we will impose no restriction on language of publication.
Searching other resources
We will check reference lists of all primary studies and review articles for additional references. We will search relevant manufacturers' websites for trial information.
We will search for errata or retractions from included studies published in full‐text on PubMed (www.ncbi.nlm.nih.gov/pubmed) and report the date of publication in the review.
Data collection and analysis
Selection of studies
Two review authors (AB and NC) will independently screen titles and abstracts for inclusion of all the potential studies we identify as a result of the search and will code them as either 'retrieve' (eligible or potentially eligible/unclear) or 'do not retrieve'. We will retrieve the full‐text study reports/publications and two review authors (AB and NC) will independently screen the full‐text articles and identify studies for inclusion, and identify and record reasons for exclusion of the ineligible studies. We will resolve any disagreement through discussion or, if required, we will consult a third review author (AH). We will identify and exclude duplicates and will collate multiple reports of the same study so that each study rather than each report is the unit of interest in the review. We will record the selection process in sufficient detail to complete a PRISMA flow diagram and 'Characteristics of excluded studies' table (Moher 2009).
Data extraction and management
We will use a data collection form that has been piloted on at least one included study in the review, to record study characteristics and outcome data. Two review authors (AB and NC) will independently extract the following study characteristics from included studies.
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Methods: study design, duration of study, study locations, study setting, date of study
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Participants: number, mean age, age range, gender, severity of condition, diagnostic criteria, baseline lung function, smoking history, inclusion criteria, exclusion criteria, withdrawals
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Interventions: intervention, comparison, concomitant interventions
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Measurement tool
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Outcomes: primary and secondary outcomes specified and collected (at baseline and at the time of intervention completion) and follow‐up measurements at any other time points noted
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Notes: funding for trial, notable conflicts of interest of trial authors
We will resolve disagreements by reaching consensus, or by involving a third review author (AH).
We will note in the 'Characteristics of included studies' table if the included studies did not report outcome data in a useable way. We will contact study authors to verify extracted data when necessary and we will provide details of missing data when possible.
One review author (AB) will transfer data into the Review Manager 5 (RevMan 5) file (Review Manager 2014). We will double‐check that the review author have entered data correctly by comparing data presented in the systematic review with data provided in the study reports. A second review author (NC) will spot‐check study characteristics for accuracy against the trial report.
Assessment of risk of bias in included studies
Two review authors (AB and NC) will independently assess risk of bias for each included RCT using the criteria outlined in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011). We will resolve disagreements by discussion or by involving another review author (AH or MA). We will assess risk of bias according to the following domains.
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Random sequence generation
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Allocation concealment
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Blinding of participants and personnel
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Blinding of outcome assessment
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Incomplete outcome data
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Selective outcome reporting
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Other bias
We will grade each potential source of bias as either high, low or unclear and will provide an extract from the study report together with a justification for our judgement. We will resolve discrepancies by consensus.
We will summarise the 'Risk of bias' judgements across different studies for each of the domains listed and summarise results in a ’Risk of bias' table.
We will consider blinding separately for different key outcomes when necessary (e.g. for unblinded outcome assessment, risk of bias for adverse events may be very different from a patient‐reported symptom scale).
When considering treatment effects, we will take into account risk of bias for studies that contribute to this outcome.
Assesment of bias in conducting the systematic review
We will conduct the review according to this published protocol and report any deviations from it in the 'Differences between protocol and review' section of the systematic review.
Measures of treatment effect
We will analyse data for each outcome, irrespective of reported participant drop out (intention‐to‐treat analysis).
We will undertake meta‐analyses only when this is meaningful (i.e. if treatments, participants and the underlying clinical question are similar enough for pooling to make clinical sense).
We will analyse dichotomous data as odds ratios and 95% confidence intervals (CIs). For continuous data we will calculate mean differences (MDs: same metric scale) or standardised mean differences (SMDs: different metric scales) with 95% CIs. We will narratively describe skewed data reported as medians and interquartile ranges.
Where multiple trial arms are reported in a single trial, we will include only the relevant trial arms. If we combine two comparisons (e.g. drug A versus placebo and drug B versus placebo) in the same meta‐analysis, we will halve the control group to avoid double‐counting.
Unit of analysis issues
Where studies randomly allocate individual participants to a physical activity intervention or control/sham we will consider the participant as the unit of analysis. We do not expect to encounter cluster‐randomised studies, but if we do then we will consider the cluster as the unit of analysis. We will exclude crossover trials due to the potential carryover effects of behavioural interventions.
Dealing with missing data
In the event of missing data, we will contact investigators or study sponsors to verify key study characteristics and to obtain missing numerical outcome data when possible (e.g. when a study is reported only as an abstract). When this is not possible, and missing data may be related to the intervention, we will analyse the impact of including such studies in the overall assessment of results by performing a sensitivity analysis.
Assessment of heterogeneity
We will use the I² statistic to measure heterogeneity among the trials in each analysis. If we identify substantial statistical heterogeneity, we will report it and explore possible causes by prespecified subgroup analyses.
Assessment of reporting biases
If we can pool more than 10 included trials, we will create a funnel plot and will analyse it to explore possible small‐study and publication biases.
Data synthesis
We will perform a pooled quantitative synthesis where the trials are clinically homogeneous. We will pool data using a random‐effects model to incorporate between study heterogeneity into the meta‐analysis. Where the trials are clinically heterogeneous we will perform a narrative synthesis. For instance, we will analyse data for different types of interventions separately, and also data for studies starting in the period following acute exacerbation separately from those in stable disease.
'Summary of findings' table
We will create a 'Summary of findings' table using the following outcomes.
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Physical activity: steps per day, energy expenditure, sedentary time and time spend in moderate to vigorous physical activity
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Adverse events
We will use the five Grading of Recommendations, Assessment, Development and Evaluation (GRADE) considerations (study limitations, consistency of effect, imprecision, indirectness and publication bias) to assess the quality of a body of evidence as it relates to studies that contribute data to the meta‐analyses for prespecified outcomes. We will use methods and recommendations described in Section 8.5 and Chapter 12 of the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011), and we will use GRADEpro Guideline Development Tool software (GRADEpro GDT 2014). We will justify all decisions to downgrade or upgrade the quality of the evidence using footnotes and we will provide comments to aid the reader's understanding of the review where necessary.
Subgroup analysis and investigation of heterogeneity
We plan to perform the following subgroup analyses.
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Duration of intervention (≤ 3 months versus > 3 months)
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Supervision of intervention (yes or no)
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Disease severity (mild disease, defined as FEV1 % predicted ≥ 80%, FER < 70, compared with other classifications)
We will use physical activity as the outcome for subgroup analyses.
We will use the formal test for subgroup interactions in Review Manager 5 (RevMan 5) (Review Manager 2014).
Sensitivity analysis
We plan to examine the effects of methodological quality on the pooled estimate by removing studies that are at high or unclear risk of bias for the domains of blinding and incomplete outcome data. Additionally, we plan to examine the effects of measurement device on the pooled estimate by removing studies that use pedometers, as previous studies suggest these may be less accurate in detecting steps in people with COPD (Pitta 2006b).
