Shuttle Walking Test as Predictor of Survival in Chronic Obstructive Pulmonary Disease Patients Enrolled in a Rehabilitation Program

Prevalence and prognostic importance of exercise limitation and physical inactivity in COPD

Exercise limitation and physical inactivity are separate, but related constructs. Both are commonly present in individuals with COPD, contribute to disease burden over and above the respiratory impairments, and are independently predictive of adverse outcomes. Because of this, clinicians should consider assessing these variables in their patients with COPD. Field tests of exercise performance such as the 6-min walk test and the incremental and endurance shuttle walk tests require limited additional resources, and results correlate with negative outcomes. Laboratory measures of exercise performance using a treadmill or cycle ergometer assess exercise capacity, provide prognostic information and have the advantage of explaining physiological mechanisms (and their interactions) underpinning exercise limitation. Limitations in exercise capacity (i.e. "cannot do") and physical inactivity (i.e. "do not do") are both associated with mortality; exercise limitation appears to be the more important driver of this outcome.

Correlation Comparison and Personalized Utility of Field Walking Tests in Assessing the Exercise Capacity of Patients with Chronic Obstructive Pulmonary Disease: A Randomized Controlled Trial

Background: Incremental shuttle walking tests (ISWT) are regarded as valuable alternatives to 6-min walking tests (6MWT) and cardiopulmonary exercise tests (CPET) owing to the maximal and externally paced loading. This study investigated the validity and reliability of ISWT by analyzing the correlation of the distances of two field tests with peak oxygen consumption (VO2) of CPET in patients with COPD. Methods: In this randomized controlled trial, patients with COPD were enrolled from two hospitals. Three assessments were performed for all patients. The ISWT and 6MWT were repeated twice in Hospital 1 to assess reliability. Results: A total of 29 patients were enrolled. The distances of ISWT (0.782, p < 0.001) and 6MWT (0.512, p = 0.005) correlated with peak VO2. The intraclass correlation coefficients of both ISWT (0.988, p < 0.001) and 6MWT (0.959, p < 0.001) was high. Patients with higher peak VO2 walked a longer distance in ISWT than 6MWT (r = 0.590, p < 0.001). Conclusions: The ISWT more highly correlates with peak VO2 than the 6MWT and has excellent reliability in patients with COPD. According to peak VO2, the walking distances of each field test varied, suggesting that the application should be personalized for the exercise capacity.

[Which physical tests for which objectives in pulmonary rehabilitation?]

Chronic respiratory disease is a major cause of morbidity and mortality worldwide and an important cause of disability including a reduction of exercise, functional and muscle capacity contributing to a decreased quality of life. In the context of pulmonary rehabilitation, a thorough patient-centered outcome assessment, including not only measures of lung function, but also exercise functional and muscle capacity, is imperative for a comprehensive disease management. Assessment of these impairments and dysfunctions with appropriate and change-sensitive procedures is thus necessary for personalizing the physical interventions and assessing the short- and long-term effectiveness of the intervention. The clinician currently has a wide variety of tests and measurements available to assess the physical and functional capacity of people with chronic respiratory disease. The aim of this review is to provide a pragmatic synthesis of the physical, functional and muscle capacity tests most commonly used in pulmonary rehabilitation. Ultimately, it should help the clinician to identify the relevant evaluations according to the objectives of the patients but also according to the available resources, the setting of pulmonary rehabilitation and the specific qualities of each test.

Validity of the Incremental Shuttle Walk Test to Assess Exercise Safety When Initiating Cardiac Rehabilitation in Low-Resource Settings

PURPOSE

To evaluate the validity of the Incremental Shuttle Walk Test (ISWT) for determining risk stratification in cardiac rehabilitation (CR).

METHODS

This is a cross-sectional study at a major CR center in a middle-income country. Clinically stable adult cardiac patients underwent an ISWT and an exercise test (ET), wore a pedometer for 7 d, and completed the Godin-Shepherd Leisure-Time Physical Activity Questionnaire. Metabolic equivalents of task (METs) achieved on the ISWT were calculated.

RESULTS

One hundred fifteen patients were evaluated. The mean ± standard deviation distance on the ISWT was 372.70 ± 128.52 m and METs were 5.03 ± 0.62. The correlation of ISWT distance with ET METs (7.57 ± 2.57), steps/d (4556.71 ± 3280.88), and self-reported exercise (13.08 ± 15.19) was rs = 0.61 (P < .001), rs = 0.37 (P < .001), and rs = 0.20 (P = .031), respectively. Distance on the ISWT accurately predicted METs from the ET (area under the receiver operating characteristic curve = 0.774). The ability to walk ≥410 m on the ISWT predicted, with a specificity of 81.5% and a sensitivity of 65.6%, a functional capacity of ≥7 METs on ET.

CONCLUSION

The ISWT is an alternative way to evaluate functional capacity in CR and can contribute to the process of identifying patients at low risk for a cardiac event during exercise at moderate intensity.

Reference equation for the incremental shuttle walk test in Portuguese children and adolescents

BACKGROUND

The incremental shuttle walk test (ISWT) is one of the most widely used field tests to assess cardiorespiratory fitness in clinical and research settings. Reference equations to predict ISWT distance in different populations and age cohorts have been established. However, an equation for the Portuguese pediatric population is not available. This study aimed to develop a reference equation for predicting ISWT in Portuguese children and adolescents.

METHOD

Healthy children and adolescents aged between 5 and 17 years old were recruited. Sociodemographic (sex, age), anthropometric (height, weight) and physical activity (Physical Activity Index) data were collected. Lung function was assessed through spirometry and quadriceps muscular strength through hand-held dynamometry. The ISWT was performed twice. A reference equation was established with a multiple linear regression.

RESULTS

130 (60 male; 13.66±2.61y) participants with normal lung function (forced expiratory volume in one second 102.73±15.09% predicted), body mass index (BMI) (20.27±3.59kg/m²) and quadriceps muscular strength (19.75±6.84kgf), completed the assessment. 50.8% (n=66) of the participants were moderately active. Participants walked on average 1165.08±327.19m in the ISWT. Sex, age and BMI were independent contributors to the ISWT, explaining 54% of its variability (p<0.001). The derived reference equation was: ISWT=342.06+(283.07×sex)+(83.61×age)-(22.22×BMI), with female=0 and male=1.

CONCLUSION

Sex, age and BMI were found to be contributors to the ISWT predictive equation for pediatric population, providing a simple reference to assess their cardiorespiratory fitness.

Reference equation for the incremental shuttle walk test in Japanese adults

BACKGROUND

The incremental shuttle walk test (ISWT) is widely used in clinical and research settings. However, there are no reference equations to predict the walk distance achieved in the ISWT (ISWD) for healthy Japanese adults. We aimed to establish a reference equation for the ISWD prediction in Japanese adults.

METHODS

The sample comprised 590 healthy Japanese subjects (237 male). All subjects performed the ISWT twice, and their anthropometric and demographic data were collected, including gender, age, height, weight, and body mass index (BMI).

RESULTS

Subjects walked 640 [490-793] m in the ISWT. The ISWD correlated (p < 0.001 for all) with age (r = - 0.51), gender (r = 0.56), weight (r = 0.39), and height (r = 0.62), but not with BMI (r = - 0.01, p = 0.74). The stepwise multiple regression model showed that age, gender, and height were independent contributors to the ISWT in healthy subjects, explaining 50% of the variability. The reference equation for the ISWD was: ISWD(m) = - 4.894 - 4.107 × Age (years) + 131.115 × Gender + 4.895 × Height (cm), where male gender = 1.

CONCLUSION

We have established a reference equation for the ISWD prediction in Japanese adults. The prediction accuracy was high (R² = 50%), and a reference equation was established using anthropometric and demographic variables that can be easily assessed in clinical settings. The reference equation developed in this study will be useful for evaluating the magnitude of exercise intolerance in Japanese adults.

Gait analysis in patients with chronic obstructive pulmonary disease: a systematic review

BACKGROUND

Gait instability is a major fall-risk factor in patients with chronic obstructive pulmonary disease (COPD). Clinical gait analysis is a reliable tool to predict fall onsets. However, controversy still exists on gait impairments associated with COPD.

RESEARCH QUESTION

Thus, the aims of this review were to evaluate the current understanding of spatiotemporal, kinematic and kinetic gait features in patients with COPD.

METHODS

In line with PRISMA guidelines, a systematic literature search was performed throughout Web of Science, PubMed Medline, Scopus, PEDro and Scielo databases. We considered observational cross-sectional studies evaluating gait features in patients with COPD as their primary outcome. Risk of bias and applicability of these papers were assessed according to the QUADAS-2 tool.

RESULTS

Seven articles, cross-sectional studies published from 2011 to 2017, met the inclusion criteria. Sample size of patients with COPD ranged 14-196 (mean age range: 64-75 years). The main reported gait abnormalities were reduced step length and cadence, and altered variability of spatiotemporal parameters. Only subtle biomechanical changes were reported at the ankle level.

SIGNIFICANCE

A convincing mechanistic link between such gait impairments and falls in patients with COPD is still lacking. The paucity of studies, small sample sizes, gender and disease status pooling were the main risk of biases affecting the results uncertainty. Two research directions emerged: stricter cohorts characterization in terms of COPD phenotype and longitudinal studies. Quantitative assessment of gait would identify abnormalities and sensorimotor postural deficiencies that in turn may lead to better falling prevention strategies in COPD.

Survival following pulmonary rehabilitation in patients with COPD: the effect of program completion and change in incremental shuttle walking test distance

Rationale

Pulmonary rehabilitation (PR) in patients with COPD has consistently been shown to produce benefits in exercise capacity, symptoms, and health status. The data surrounding survival following PR are less clear. Our aims were to compare the long-term survival in two cohorts of patients referred for PR; those who successfully completed PR, and a comparator group constructed from patients who either did not complete PR or did not start the program. Additionally, we compared survival between those people who were able to achieve a clinically meaningful improvement in exercise capacity (incremental shuttle walking test) following PR with those who were not.

Methods

A retrospective longitudinal analysis of clinical service outcomes was conducted to compare the long-term survival in "completers" and "non-completers" of rehabilitation at two hospitals within the University Hospitals of Leicester NHS Trust from January 1, 2000 to February 23, 2012. For "completers", we also analyzed survival in those meeting (and not meeting) the desired level of change in the incremental shuttle walking test (≥50 m vs <50 m).

Results

We present to you the largest dataset on this topic (n=1,515). Survival data were ascertained for 823 (54.3%) patients with COPD who had completed a course of PR and for 692 (45.7%) patients who dropped out. Survival time was significantly greater in "completers" compared to "non-completers" of PR (p<0.001). In addition, PR success (≥50 m change in walking distance) was also associated with improved survival (p<0.05).

Conclusion

The data show an association between completion of PR and survival. In addition, PR success (>50 m change in walking distance) was also associated with improved survival.

Measurement Properties of Short Lower Extremity Functional Exercise Tests in People With Chronic Obstructive Pulmonary Disease: Systematic Review

BACKGROUND

An increasing variety of short functional exercise tests are reported in people with chronic obstructive pulmonary disease (COPD). Systematic review of the psychometric properties of these exercise tests is indicated.

PURPOSE

The aim of this study was to determine the reliability, validity, and responsiveness of short (duration < 6 min) lower extremity functional exercise tests in people with COPD.

DATA SOURCES

Five databases were searched: MEDLINE, Embase, Scopus, AMED, and CINAHL.

STUDY SELECTION

Studies reporting psychometric properties of short functional exercise tests in people with COPD were included.

DATA EXTRACTION

Two reviewers independently extracted data and rated the quality of each measurement property using the COnsensus-based Standards for the Selection of Health Measurement INstrument (COSMIN).

DATA SYNTHESIS

Twenty-nine studies were identified reporting properties of 11 different tests. Four-meter gait speed [4MGS] and 5 repetition sit-to-stand [5STS] demonstrated high reliability (ICC = .95-.99; .97) with no learning effect (COSMIN study ratings = good--excellent). Their validity for use as a stratification tool anchored against an established prognostic indicator (area under receiver operator characteristics curve [AUC] = 0.72-0.87; 0.82) and responsiveness to change after pulmonary rehabilitation was greatest in more frail people with COPD. Studies of the Timed "Up and Go" [TUG] test support use of a practice test and show discriminative ability to detect falls history and low six-minute walk distance (AUC = 0.77; 0.82, COSMIN ratings = fair-excellent).

LIMITATIONS

Earlier studies were limited by small sample size. Limited data of lower study quality was identified for step tests and the Two-Minute Walk Test.

CONCLUSIONS

Selected short functional exercise tests can complement established exercise capacity measures, in stratification and measuring responsiveness to change especially in people with COPD and lower functional ability.

Tablet computers to support outpatient pulmonary rehabilitation in patients with COPD

Background

A minicomputer (tablet) with instructions and a training diary has the potential of facilitating adherence to pulmonary rehabilitation (PR).

Objective

To evaluate the effect of adding a tablet to a classic outpatient PR programme for COPD patients.

Methods

A total of 115 patients participated in a 7- to 10-week outpatient PR programme in groups of 10–12 individuals. Half of the groups were assigned to PR plus a tablet (tablet group) and the other groups were assigned to PR only (controls). Primary effect parameters were endurance shuttle walk time (ESWT) and disease-specific health status (COPD Assessment Test=CAT).

Results

The change in ESWT was significantly better in the control group (mean 167 sec) compared with the tablet group (mean 51 sec) (p<0.01), whereas the change in CAT score did not differ significantly between the two groups (−0.6 vs. −2.3) (p=0.17).

Conclusions

Compared with usual PR, no significant improvements were seen in the group equipped with the tablet after 7–10 weeks of rehabilitation. Future studies should focus on long-term effects.

Use of exercise testing in the evaluation of interventional efficacy: an official ERS statement

This document reviews 1) the measurement properties of commonly used exercise tests in patients with chronic respiratory diseases and 2) published studies on their utilty and/or evaluation obtained from MEDLINE and Cochrane Library searches between 1990 and March 2015.

Exercise tests are reliable and consistently responsive to rehabilitative and pharmacological interventions. Thresholds for clinically important changes in performance are available for several tests. In pulmonary arterial hypertension, the 6-min walk test (6MWT), peak oxygen uptake and ventilation/carbon dioxide output indices appear to be the variables most responsive to vasodilators. While bronchodilators do not always show clinically relevant effects in chronic obstructive pulmonary disease, high-intensity constant work-rate (endurance) tests (CWRET) are considerably more responsive than incremental exercise tests and 6MWTs. High-intensity CWRETs need to be standardised to reduce interindividual variability. Additional physiological information and responsiveness can be obtained from isotime measurements, particularly of inspiratory capacity and dyspnoea. Less evidence is available for the endurance shuttle walk test. Although the incremental shuttle walk test and 6MWT are reliable and less expensive than cardiopulmonary exercise testing, two repetitions are needed at baseline. All exercise tests are safe when recommended precautions are followed, with evidence suggesting that no test is safer than others.

Reference Equation for the Incremental Shuttle Walk Test in Children and Adolescents

OBJECTIVE

To determine a prediction equation for distance walked of incremental shuttle walk test (ISWT) and test its reliability in children and adolescents.

STUDY DESIGN

Cross-sectional study, which included 108 healthy volunteers between 6 and 18 years old. Those who had an abnormal spirometry or had a history of chronic disease were excluded. Two ISWT were performed. Heart rate and peripheral capillary oxygen saturation (SpO2) were continuously measured during the test. Dyspnea and lower limb fatigue were assessed by Borg scale before and after the tests.

RESULTS

Boys walked longer distances compared with girls (1066.4 ± 254.1 m vs 889.7 ± 159.6 m, respectively, P < .0001). Except for dyspnea, there were no significant differences in the other outcomes measured (heart rate, lower limb fatigue, SpO2, and distance walked) at the peak of the two ISWT. The variables included in the predicted equation were age, body mass index, and sex. The predicted equation is: ISWTpred = 845.559 + (sex * 193.265) + (age * 47.850) - (body mass index * 26.179). The distance walked had an excellent reliability between the two ISWT, 0.98 (95% CI 0.97-0.99). The Bland-Altman plot shows agreement between tests (range from -40 to 45 m).

CONCLUSIONS

We established a prediction equation for ISWT. It can be used as a reference to evaluate exercise capacity for children and adolescents. ISWT has excellent repeatability and it is a maximal-effort field test for this age group.

How to carry out a field walking test in chronic respiratory disease

EDUCATIONAL AIMS

To provide recommendations for conducting field walking tests in people with chronic respiratory disease, from the new European Respiratory Society/American Thoracic Society Technical StandardTo provide information to assist in selecting a field walking test in people with chronic respiratory disease.

KEY POINTS

The 6MWT, ISWT and ESWT are valid and reliable tests of functional exercise capacity in people with COPD. The 6MWT is also widely used in other chronic respiratory disorders.There is a learning effect for the 6MWT and ISWT, so two tests must be performed if the tests are being used to measure change over time, with the best distance recorded.The 6MWT is very sensitive to changes in the way it is conducted, including use of encouragement, provision of supplemental oxygen, changes in track layout and length, and use of wheeled walkers. These factors should be held constant when the test is repeated.The 6MWT, ISWT and ESWT are strenuous tests, with cardiorespiratory responses that are similar to those during a maximal incremental exercise test. As a result, the contraindications and precautions for these field walking tests should be the same as for a laboratory-based incremental exercise test.

SUMMARY

The European Respiratory Society (ERS) and American Thoracic Society (ATS) have recently published a Technical Standard which documents the standard operating procedures for the 6-min walk test (6MWT), incremental shuttle walk test (ISWT) and endurance shuttle walk test (ESWT). The Technical Standard shows that all three tests are valid and reliable measures of functional exercise capacity in people with chronic respiratory disease and makes recommendations for standardising their performance. Key findings and recommendations of the Technical Standard include: The 6MWT, ISWT and ESWT are strenuous tests which elicit cardiorespiratory responses that are similar to those observed during a maximal incremental exercise test. As a result, the contraindications and precautions for field walking tests should be consistent with those used for a laboratory-based incremental exercise test.There is strong evidence of a learning effect for the 6MWT and ISWT. Two tests should be performed when the 6MWT or ISWT are used to measure change over time.The 6MWT, ISWT and ESWT are responsive to treatment effects in people with chronic respiratory disease, particularly for rehabilitation.The 6MWT is very sensitive to variations in methodology, including use of encouragement, provision of supplemental oxygen, changes in track layout and length, and use of wheeled walkers. These factors should be documented and held constant on repeat testing.The lowest S pO2 recorded during a 6MWT is an important marker of disease severity and prognosis. Continuous pulse oximetry is recommended during the 6MWT, to ensure that the lowest S pO2 is recorded.In adults with chronic respiratory disease, a change in 6-min walk distance of 30 m or more indicates a clinically significant change has occurred.

Effects of a pulmonary rehabilitation program on physical capacity, peripheral muscle function and inflammatory markers in asthmatic children and adolescents: study protocol for a randomized controlled trial

Background

Individuals with chronic lung disease are more susceptible to present reduction in exercise tolerance and muscles strength not only due to pulmonary limitations but also due systemic repercussions of the pulmonary disease.

The aim of this study is to assess the physical capacity, peripheral muscle function, physical activity in daily life, and the inflammatory markers in children and adolescents with asthma after pulmonary rehabilitation program.

Method

This is a study protocol of randomized controlled trial in asthmatic patients between 6 to 18 years old. The assessments will be conducted in three different days and will be performed at the beginning and at the end of the protocol. First visit: quality of life questionnaire, asthma control questionnaire, pre- and post-bronchodilator spirometry (400 μcg salbutamol), inflammatory assessment (blood collection), and cardiopulmonary exercise test on a cycle ergometer to determine aerobic capacity. Second visit: assessment of strength and endurance of the quadriceps femoris and biceps brachii muscles with concomitant electromyography to assess peripheral muscle strength. Third visit: incremental shuttle walk test (ISWT) and accelerometer to evaluate functional capacity and physical activity in daily life during 7 days. Then, the volunteers will be randomized to receive pulmonary rehabilitation program (intervention group) or chest physiotherapy + stretching exercises (control group). Both groups will have a supervised session, twice a week, each session will have 60 minutes duration, with minimum interval of 24 hours, for a period of 8 weeks. Intervention group: aerobic training (35 minutes) intensity between 60 to 80 % of the maximum workload of cardiopulmonary exercise testing or of ISWT; strength muscle training will be applied to the quadriceps femoris, biceps brachii and deltoid muscles (intensity: 40 to 70 % of maximal repetition, 3 x 8 repetition); finally the oral high-frequency oscillation device (Flutter®) will be used for 5 minutes. The control group: oral high-frequency oscillation device (Flutter®) for 10 minutes followed by the stretching of upper and lower limbs for 40 minutes. It is expected to observe the improvement in aerobic capacity, physical activity in daily life, muscle strength and quality of life of patients in the intervention group, and reduction in inflammatory markers.

Trial registration

Clinical Trial Number: NCT02383069. Data of registration: 03/03/2015

Systematic Review of the Association Between Laboratory- and Field-Based Exercise Tests and Lung Function in Patients with Chronic Obstructive Pulmonary Disease

Introduction: Typical symptoms of chronic obstructive pulmonary disease (COPD) include breathlessness and reduced exercise capacity. Several laboratory- and field-based exercise tests are used to assess the exercise capacity of patients with COPD. It is unclear whether these exercise tests reflect the spirometric measures recommended for diagnosis of COPD. We therefore aimed to systematically assess the correlation between these exercise tests and common measures of lung function. Methods: A search of Embase™, MEDLINE^® and The Cochrane Library identified primary publications in English that reported data on the correlations (Pearson's r or Spearman's rho) between the outcomes of exercise tests and the physiological measures of interest: forced expiratory volume in 1 second (FEV₁), forced vital capacity, inspiratory capacity and arterial oxygen saturation. We included studies reporting on the following exercise tests: 6- and 12-minute walk tests (6MWT and 12 MWT), incremental and endurance shuttle walk tests, incremental and endurance cycle ergometer tests, and treadmill tests. Results: Of 1781 articles screened, 45 were ultimately deemed eligible for inclusion in this review. The most commonly reported lung function variable was FEV₁ (reported by 39 studies); the most commonly reported exercise test was the 6-minute walk test (reported by 24 studies). FEV₁ appears to correlate moderately-to-strongly with 6MWT and 12MWT; and moderately-to-very strongly with incremental cycle ergometer tests (ICET); evidence for other exercise tests was limited. Conclusion: There is evidence that 6MWT, 12MWT and ICET correlate with FEV₁ to some degree; - evidence for associations of other exercise tests with measures of lung function in patients with COPD is limited. Clinicians must consider this when deciding to use these tests. Further comparisons of these tests must be made in order to assess which physiological and hemodynamic characteristics they reflect in patients with COPD.

A cross-sectional study of the prevalence and associations of iron deficiency in a cohort of patients with chronic obstructive pulmonary disease

OBJECTIVES

Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality. Iron deficiency, with or without anaemia, is associated with other chronic conditions, such as congestive heart failure, where it predicts a worse outcome. However, the prevalence of iron deficiency in COPD is unknown. This observational study aimed to determine the prevalence of iron deficiency in COPD and associations with differences in clinical phenotype.

SETTING

University hospital outpatient clinic.

PARTICIPANTS

113 adult patients (65% male) with COPD diagnosed according to GOLD criteria (forced expiratory volume in 1 s (FEV1): forced vital capacity (FVC) ratio <0·70 and FEV1 <80% predicted); with age-matched and sex-matched control group consisting of 57 healthy individuals.

MAIN OUTCOME MEASURES

Prevalence of iron deficiency, defined as: any one or more of (1) soluble transferrin receptor >28.1 nmol/L; (2) transferrin saturation <16% and (3) ferritin <12 µg/L. Severity of hypoxaemia, including resting peripheral arterial oxygen saturation (SpO2) and nocturnal oximetry; C reactive protein (CRP); FEV1; self-reported exacerbation rate and Shuttle Walk Test performance.

RESULTS

Iron deficiency was more common in patients with COPD (18%) compared with controls (5%). In the COPD cohort, CRP was higher in patients with iron deficiency (median 10.5 vs 4.0 mg/L, p<0.001), who were also more hypoxaemic than their iron-replete counterparts (median resting SpO2 92% vs 95%, p<0.001), but haemoglobin concentration did not differ. Patients with iron deficiency had more self-reported exacerbations and a trend towards worse exercise tolerance.

CONCLUSIONS

Non-anaemic iron deficiency is common in COPD and appears to be driven by inflammation. Iron deficiency associates with hypoxaemia, an excess of exacerbations and, possibly, worse exercise tolerance, all markers of poor prognosis. Given that it has been shown to be beneficial in other chronic diseases, intravenous iron therapy should be explored as a novel therapeutic option in COPD.

An official European Respiratory Society/American Thoracic Society technical standard: field walking tests in chronic respiratory disease

Field walking tests are commonly employed to evaluate exercise capacity, assess prognosis and evaluate treatment response in chronic respiratory diseases. In recent years, there has been a wealth of new literature pertinent to the conduct of the 6-min walk test (6MWT), and a growing evidence base describing the incremental and endurance shuttle walk tests (ISWT and ESWT, respectively). The aim of this document is to describe the standard operating procedures for the 6MWT, ISWT and ESWT, which can be consistently employed by clinicians and researchers. The Technical Standard was developed by a multidisciplinary and international group of clinicians and researchers with expertise in the application of field walking tests. The procedures are underpinned by a concurrent systematic review of literature relevant to measurement properties and test conduct in adults with chronic respiratory disease. Current data confirm that the 6MWT, ISWT and ESWT are valid, reliable and responsive to change with some interventions. However, results are sensitive to small changes in methodology. It is important that two tests are conducted for the 6MWT and ISWT. This Technical Standard for field walking tests reflects current evidence regarding procedures that should be used to achieve robust results.

An official systematic review of the European Respiratory Society/American Thoracic Society: measurement properties of field walking tests in chronic respiratory disease

This systematic review examined the measurement properties of the 6-min walk test (6MWT), incremental shuttle walk test (ISWT) and endurance shuttle walk test (ESWT) in adults with chronic respiratory disease.

Studies that report the evaluation or use of the 6MWT, ISWT or ESWT were included. We searched electronic databases for studies published between January 2000 and September 2013.

The 6-min walking distance (6MWD) is a reliable measure (intra-class correlation coefficients ranged from 0.82 to 0.99 in seven studies). There is a learning effect, with greater distance walked on the second test (pooled mean improvement of 26 m in 13 studies). Reliability was similar for ISWT and ESWT, with a learning effect also evident for ISWT (pooled mean improvement of 20 m in six studies). The 6MWD correlates more strongly with peak work capacity (r=0.59–0.93) and physical activity (r=0.40–0.85) than with respiratory function (r=0.10–0.59). Methodological factors affecting 6MWD include track length, encouragement, supplemental oxygen and walking aids. Supplemental oxygen also affects ISWT and ESWT performance. Responsiveness was moderate to high for all tests, with greater responsiveness to interventions that included exercise training.

The findings of this review demonstrate that the 6MWT, ISWT and ESWT are robust tests of functional exercise capacity in adults with chronic respiratory disease.

Adherence to a maintenance exercise program 1 year after pulmonary rehabilitation: what are the predictors of dropout?

PURPOSE

To evaluate adherence to a maintenance exercise program in patients with chronic obstructive pulmonary disease (COPD) and explore predictors for adherence.

METHODS

Seventy patients with COPD were referred to a home-care maintenance exercise program after completing pulmonary rehabilitation (PR) in the rehabilitation center. Adherence (yes/no) to the maintenance program was assessed by a self-reported questionnaire, where adherence was defined as attending the maintenance program 1 year after PR. Early dropouts received a self-reported questionnaire after 6 months and the remaining patients after 12 months. Lung function, exercise capacity, exercise self-efficacy, illness perceptions, health-related quality of life, levels of anxiety and depression, duration of PR, and the number of exacerbations were studied as possible predictors of adherence.

RESULTS

Ten patients died or were lost to followup. Of the remaining 60 patients, 73.3% and 63.3% were adherent to the maintenance exercise program after 6 and 12 months, respectively. Forced expiratory volume in 1 second (FEV1) (P = .021), Hospital Anxiety and Depression Scale depression score (P = .025), and duration of PR (P = .018) were significant predictors of adherence to the maintenance program.

CONCLUSION

Adherence to the maintenance exercise program included a 36.7% drop-out rate during the first year after completing PR. Experiencing exacerbations was the most reported reason for dropout. Poorer lung function, shorter initial PR course measured by reviewing patient records, and higher level of depressive symptoms were predictive of drop-out to the maintenance program. Adherence to the maintenance program needs to be improved for patients with lower FEV1, with signs of depression, or with a shorter initial PR course.

Predictors of all-cause mortality in patients with stable COPD: medical co-morbid conditions or high depressive symptoms

Co-morbid conditions are frequently found in patients with COPD. We evaluate the association of co-morbidities with mortality, in stable COPD. 224 patients, mean age 61.2 (± 10.00), 48.2% female, mean FEV1 1.1 (± 0.5) liters, median follow-up time 4.2 years, participated. Medical co-morbidities were scored according to the Charlson Co-morbidity Index (CCI). Depressive symptoms were assessed with the Hospital Anxiety and Depression Scale (HADS) and Symptom Checklist-90 (SCL-90). The Cox proportional hazard model was used for survival analyses. In our sample, 70% of all patients have a co-morbid medical condition or high depressive symptoms. During follow-up 51% of all patients died, and those with heart failure have the highest mortality rate (75%). Age, fat-free mass and exercise capacity were predictive factors, contrary to CCI-scores and high depressive symptoms. An unadjusted association between heart failure and survival was found. Although the presence of co-morbidities, using the CCI-score, is not related to survival, heart failure seems to have a detrimental effect on survival. Higher age and lower exercise capacity or fat-free mass predict mortality.

Directly measured physical activity as a predictor of hospitalizations in patients with chronic obstructive pulmonary disease

Patients with clinically stable chronic obstructive pulmonary disease (COPD) are physically inactive, and this inactivity appears to be an independent predictor of hospitalizations. To explore this relationship further, we compared physical activity of COPD patients assessed in 2008 to subsequent hospitalizations and mortality. Sixty adults with a history of cigarette smoking, a diagnosis of COPD, a forced expiratory volume in 1 second (FEV1)/forced vital capacity (FVC) of <0.70, and no recent exacerbation were studied. Physical activity was measured using a triaxial accelerometerworn on the waist for seven consecutive days and the vector magnitude units (VMUs) that are the sum of movements in three planes over each minute were recorded. Those patients with mean VMU<170 (the median) were considered to be less physically active, and those with a 6-minute walk distance (6MWD) test of <350 m were considered to have lower functional exercise capacity. These two variables, along with age, gender, and a history of exacerbations in the preceding 12 months, FEV1, body mass index, and supplemental oxygen requirement, were related to subsequent all-cause and respiratory-related hospitalizations that occurred over the ensuing 53±2 months. The mean age was 68±11 years, 50% were male, and the FEV1 was 53±19%. All-cause and respiratory-related hospitalizations occurred in 58 and 35%, respectively. A 6MWD<350 m and VMU<170 each significantly predicted subsequent all-cause and respiratory-related hospitalizations in univariate Cox proportional hazards analyses after controlling for previous exacerbations. Both 6MWD<350 m and VMU<170 counts remained in a multivariate model predicting respiratory-related hospitalization. These results indicate that both directly measured physical activity and functional exercise capacity are important predictors of hospitalization in COPD.

Reference values for the incremental shuttle walk test in healthy subjects: from the walk distance to physiological responses

OBJECTIVE:

To determine reference values for incremental shuttle walk distance (ISWD) and peak physiological responses during the incremental shuttle walk test (ISWT), as well as to develop a series of predictive equations for those variables in healthy adults.

METHODS:

We evaluated 103 healthy participants ≥ 40 years of age (54 women and 49 men). We fitted each participant with a gas analysis system for use during the ISWT. Oxygen consumption (VO₂), carbon dioxide production, minute ventilation, heart rate (HR), ISWD, and maximal walking velocity (MWV) were obtained as primary outcomes. We also assessed hand grip strength (HGS) and lean body mass (LBM).

RESULTS:

The regression analysis models, including physiological variables, ISWD, and MWV (adjusted for age, body mass, height, and sex), produced R² values ranging from 0.40 to 0.65 (for HR and peak VO₂, respectively). Using the models including LBM or HGS, we obtained no significant increase in the R² values for predicting peak VO₂, although the use of those models did result in slight increases in the R² values for ISWD and MWV (of 8% and 12%, respectively). The variables ISWD, MWV, and ISWD × body mass, respectively, explained 76.7%, 73.3%, and 81.2% of peak VO₂ variability.

CONCLUSIONS:

Our results provide reference values for ISWD and physiological responses to the ISWT, which can be properly estimated by determining simple demographic and anthropometric characteristics in healthy adults ≥ 40 years of age. The ISWT could be used in assessing physical fitness in the general adult population and in designing individualized walking programs.

Body mass index and mortality in chronic obstructive pulmonary disease: a meta-analysis

Background

The association between body mass index (BMI) and mortality in patients suffering from chronic obstructive pulmonary disease (COPD) has been a subject of interest for decades. However, the evidence is inadequate to draw robust conclusions because some studies were generally small or with a short follow-up.

Methods

We carried out a search in MEDLINE, Cochrane Central Register of Controlled Trials, and EMBASE database for relevant studies. Relative risks (RRs) with 95% confidence interval (CI) were calculated to assess the association between BMI and mortality in patients with COPD. In addition, a baseline risk-adjusted analysis was performed to investigate the strength of this association.

Results

22 studies comprising 21,150 participants were included in this analysis. Compared with patients having a normal BMI, underweight individuals were associated with higher mortality (RR  = 1.34, 95% CI  = 1.01–1.78), whereas overweight (RR  = 0.47, 95% CI  = 0.33–0.68) and obese (RR  = 0.59, 95% CI  = 0.38–0.91) patients were associated with lower mortality. We further performed a baseline risk-adjusted analysis and obtained statistically similar results.

Conclusion

Our study showed that for patients with COPD being overweight or obese had a protective effect against mortality. However, the relationship between BMI and mortality in different classes of obesity needed further clarification in well-designed clinical studies.

Measuring walking speed in COPD: test-retest reliability of the 30-metre walk test and comparison with the 6-minute walk test

AIMS

To examine test-retest reliability of the 30-metre walk test (30mWT) in patients with chronic obstructive pulmonary disease (COPD) and to compare the 30mWT with the 6-minute walk test (6MWT).

METHODS

Forty-nine subjects with stable COPD were included. The 30mWT consists of walking at different walking intensities over a distance of 30 metres - self-selected speed (ss-30mWT) and maximal speed (ms-30mWT). The test was conducted twice and the time to walk 30 metres was recorded. The 6MWT was performed in duplicate on the same day.

RESULTS

Test-retest reliability was high: intraclass correlation coefficient (ICC(2.1)) = 0.93 (95% CI 0.87 to 0.97) for maximal walking speed and 0.87 (95% CI 0.78 to 0.93) for self-selected walking speed. Both maximal and self-selected speed had a standard error of measurement (SEM) of 0.07 m/s and SEM% was 4.4 for maximal speed and 5.9 for self-selected speed. The correlation, criterion validity, between ms-30mWT and the 6MWT was r=0.78 (p<0.001). Heart rate, dyspnoea, exertion and oxygen saturation were more affected after the 6MWT than after the 30mWT (p<0.001).

CONCLUSIONS

The 30mWT is a reliable submaximal test that is easy to perform and can be used to measure physical function (walking ability) in patients with COPD. It may be well suited for primary care settings.

Development of the i-BODE: validation of the incremental shuttle walking test within the BODE index

BACKGROUND

The BODE index has been shown to predict mortality in COPD. The index includes the 6 min walking test as the measure of exercise capacity. The incremental shuttle walking test (ISWT) is an alternative measure of exercise capacity which can be used to prescribe exercise and has been found to correlate well with peak VO2. The objective of the study was to evaluate the incorporation of the ISWT within the BODE index (named the i-BODE) to predict mortality in COPD.

METHODS

Data was analysed from 633 patients with COPD attending pulmonary rehabilitation over an 11 year period, and mortality determined a minimum of one year on from initial assessment. An i-BODE score was calculated using ISWT(m) then Cox regression analysis evaluated the capacity of the index to predict risk of death.

RESULTS

BMI, ISWT (m), MRC dyspnoea score, pack years and age were all significantly associated with mortality. Cox regression revealed the i-BODE index was an independent and significant predictor of mortality (hazard ratio 1.27 (CI 1.17-1.35), p < 0.001) and Kaplan Meier survival analysis showed each quartile increase in severity in i-BODE score was significantly associated with increased mortality (p < 0.001 by log rank test).

CONCLUSION

We have found the i-BODE index to be an independent predictor of mortality in COPD, even when other strong predictors such as age and pack years are adjusted for. We conclude that the ISWT can be successfully substituted for the 6MWT as an alternative measure of exercise capacity within the BODE index.

The accuracy of a simple, low-cost GPS data logger/receiver to study outdoor human walking in view of health and clinical studies

INTRODUCTION

Accurate and objective measurements of physical activity and lower-extremity function are important in health and disease monitoring, particularly given the current epidemic of chronic diseases and their related functional impairment.

PURPOSE

The aim of the present study was to determine the accuracy of a handy (lightweight, small, only one stop/start button) and low-cost (∼$75 with its external antenna) Global Positioning System (GPS) data logger/receiver (the DG100) as a tool to study outdoor human walking in perspective of health and clinical research studies. Methods. Healthy subjects performed two experiments that consisted of different prescribed outdoor walking protocols. Experiment 1. We studied the accuracy of the DG100 for detecting bouts of walking and resting. Experiment 2. We studied the accuracy of the DG100 for estimating distances and speeds of walking.

RESULTS

Experiment 1. The performance in the detection of bouts, expressed as the percentage of walking and resting bouts that were correctly detected, was 92.4% [95% Confidence Interval: 90.6-94.3]. Experiment 2. The coefficients of variation [95% Confidence Interval] for the accuracy of estimating the distances and speeds of walking were low: 3.1% [2.9-3.3] and 2.8% [2.6-3.1], respectively.

CONCLUSION

The DG100 produces acceptable accuracy both in detecting bouts of walking and resting and in estimating distances and speeds of walking during the detected walking bouts. However, before we can confirm that the DG100 can be used to study walking with respect to health and clinical studies, the inter- and intra-DG100 variability should be studied.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00485147.