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Short Physical Performance Battery: Response to Pulmonary Rehabilitation and Minimal Important Difference Estimates in Patients With Chronic Obstructive Pulmonary Disease
⁎ Stoffels and De Brandt contributed equally to this work.
Anouk A. Stoffels
Correspondence
Corresponding author Anouk A. Stoffels, MSc, Department Pulmonary Diseases, Dekkerswald Radboud University Medical Center, Radboud Institute for Health Sciences, Radboudumc, Geert Grooteplein Zuid 10, 6525 GA Nijmegen, The Netherlands.
⁎ Stoffels and De Brandt contributed equally to this work.
Affiliations
Department of Pulmonary Diseases, Dekkerswald Radboud University Medical Centre, Radboud Institute for Health Sciences, Nijmegen, the NetherlandsDepartment of Research and Development, CIRO, Horn, the NetherlandsDepartment of Respiratory Medicine, Maastricht University Medical Centre (MUMC+), NUTRIM School of Nutrition and Translational Research in Metabolism, Faculty of Health, Medicine and Life Sciences, Maastricht, The Netherlands
⁎ Stoffels and De Brandt contributed equally to this work.
Jana De Brandt
Footnotes
⁎ Stoffels and De Brandt contributed equally to this work.
Affiliations
REVAL–Rehabilitation Research Center, BIOMED–Biomedical Research Institute, Faculty of Rehabilitation Sciences, Hasselt University, Diepenbeek, Belgium
Department of Research and Development, CIRO, Horn, the NetherlandsDepartment of Respiratory Medicine, Maastricht University Medical Centre (MUMC+), NUTRIM School of Nutrition and Translational Research in Metabolism, Faculty of Health, Medicine and Life Sciences, Maastricht, The Netherlands
Department of Pulmonology, Merem Pulmonary Rehabilitation Centre, Hilversum, the NetherlandsDepartment of Pulmonary, Amsterdam University Medical Centre, Amsterdam, the Netherlands
REVAL–Rehabilitation Research Center, BIOMED–Biomedical Research Institute, Faculty of Rehabilitation Sciences, Hasselt University, Diepenbeek, Belgium
Department of Research and Development, CIRO, Horn, the NetherlandsDepartment of Respiratory Medicine, Maastricht University Medical Centre (MUMC+), NUTRIM School of Nutrition and Translational Research in Metabolism, Faculty of Health, Medicine and Life Sciences, Maastricht, The Netherlands
Department of Research and Development, CIRO, Horn, the NetherlandsDepartment of Health Services Research, Care and Public Health Research Institute, Faculty of Health Medicine and Life Sciences, Maastricht University, Maastricht, the Netherlands
Department of Research and Development, CIRO, Horn, the NetherlandsDepartment of Respiratory Medicine, Maastricht University Medical Centre (MUMC+), NUTRIM School of Nutrition and Translational Research in Metabolism, Faculty of Health, Medicine and Life Sciences, Maastricht, The NetherlandsREVAL–Rehabilitation Research Center, BIOMED–Biomedical Research Institute, Faculty of Rehabilitation Sciences, Hasselt University, Diepenbeek, Belgium
To determine the response to a pulmonary rehabilitation (PR) program and minimal important differences (MIDs) for the Short Physical Performance Battery (SPPB) subtests and SPPB summary score in patients with chronic obstructive pulmonary disease (COPD).
Design
Retrospective analysis using distribution- and anchor-based methods.
Setting
PR center in the Netherlands including a comprehensive 40-session 8-week inpatient or 14-week outpatient program.
Participants
A total of 632 patients with COPD (age, 65±8y; 50% male; forced expiratory volume in the first second=43% [interquartile range, 30%-60%] predicted).
Interventions
Not applicable.
Main Outcome Measure
Baseline and post-PR results of the SPPB, consisting of 3 balance standing tests, 4-meter gait speed (4MGS), and 5-repetition sit-to-stand (5STS). The chosen anchors were the 6-Minute Walk Test and COPD Assessment Test. Patients were stratified according to their SPPB summary scores into low-performance, moderate-performance, and high-performance groups.
Results
5STS (∆=−1.14 [−4.20 to −0.93]s) and SPPB summary score (∆=1 [0-2] points) improved after PR in patients with COPD. In patients with a low performance at baseline, balance tandem and 4MGS significantly increased as well. Based on distribution-based calculations, the MID estimates ranged between 2.19 and 6.33 seconds for 5STS and 0.83 to 0.96 points for SPPB summary score.
Conclusions
The 5STS and SPPB summary score are both responsive to PR in patients with COPD. The balance tandem test and 4MGS are only responsive to PR in patients with COPD with a low performance at baseline. Based on distribution-based calculations, an MID estimate of 1 point for the SPPB summary score is recommended in patients with COPD. Future research is needed to confirm MID estimates for SPPB in different centers.
The Short Physical Performance Battery (SPPB) is an easy-to-perform measure for assessment of mobility and balance and its use is intended and recommended for older persons (>65y).
However, there is an increasing interest in SPPB performance for diseased populations, including individuals with chronic obstructive pulmonary disease (COPD). COPD is defined by the Global Initiative for Chronic Obstructive Lung Disease (GOLD) as “a common, preventable and treatable disease that is characterized by persistent respiratory symptoms and airflow limitation that is due to airway and/or alveolar abnormalities caused by significant exposure to noxious particles or gases.”
GOLD. 2021 Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease. Available at https://goldcopd.org/2021-gold-reports/. Accessed March 4, 2021
Interobserver reliability of peripheral muscle strength tests and Short Physical Performance Battery in patients with chronic obstructive pulmonary disease: a prospective observational study.
Phenotypic characteristics of patients with chronic obstructive pulmonary disease after stratification for the Short Physical Performance Battery summary score.
Phenotypic characteristics of patients with chronic obstructive pulmonary disease after stratification for the Short Physical Performance Battery summary score.
The latter might suggest a positive effect of pulmonary rehabilitation (PR) on the SPPB summary score. To date, the response of the SPPB summary score to PR has only been described in 1 peer-reviewed manuscript
Thus, to improve the interpretation of intervention efficacy at individual and group levels, the aims of the present study were to determine the response to a PR program on the SPPB subtests and summary score in patients with COPD and to estimate MIDs for the SPPB subtests and summary score in patients with COPD.
Methods
In this observational study, a retrospective analysis was performed on baseline and post-PR data of 953 patients between January 2016 and January 2018 in CIRO, a specialized PR center in the Netherlands.
This study was performed in accordance with the principles of the Declaration of Helsinki and was approved by the board of directors. The authors were informed by the Medical Ethics Committee of Maastricht University that the Medical Research Involving Human Subjects Act does not apply and no official approval was required (MEC no. 2018-0541). Therefore, no informed consent from participants was obtained.
The following inclusion criteria were applied: primary diagnosis of COPD according to the GOLD criteria
GOLD. 2021 Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease. Available at https://goldcopd.org/2021-gold-reports/. Accessed March 4, 2021
and complete SPPB data (baseline and post-PR) available. Participants younger than 40 years old, participation in the PR program more than once, or a baseline SPPB summary score of 12, because of a possible ceiling effect,
Phenotypic characteristics of patients with chronic obstructive pulmonary disease after stratification for the Short Physical Performance Battery summary score.
Baseline characteristics including age, sex, weight, body mass index, exacerbation and hospitalization frequency in the last 12 months, Charlson Comorbidity Index, and use of long-term oxygen therapy were systematically collected during an extensive PR assessment. Furthermore, forced expiratory volume in 1 second and its ratio to forced vital capacity were assessed in accordance with the European Respiratory Society recommendations
Lung volumes and forced ventilatory flows. report working party standardization of lung function tests, European Community for Steel and Coal. Official Statement of the European Respiratory Society.
GOLD. 2021 Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease. Available at https://goldcopd.org/2021-gold-reports/. Accessed March 4, 2021
A Short Physical Performance Battery assessing lower extremity function: association with self-reported disability and prediction of mortality and nursing home admission.
The SPPB includes 3 subtests: the standing balance test, 4MGS, and 5STS. During the standing balance test the patient was instructed to maintain 3 stances (feet placed side by side, semi-tandem, tandem) for 10 seconds. Secondly, the 4MGS was performed in duplicate to obtain the habitual gait speed over 4 m (normal walking aids were allowed). In the 5STS, the patient was required to perform 5 sit-to-stand maneuvers as fast as possible with arms folded in front of their chest. Each of the 3 components was scored from 0 (extreme mobility impairment) to 4 points (no mobility impairment), resulting in a SPPB summary score ranging from 0-12 points (table E1, available online only at http://www.archives-pmr.org/). A flowchart of the SPPB subtests and its scoring system was previously reported by Nogueira et al.
According to their baseline SPPB summary score, patients were classified as low performance (LP; 0-6 points), moderate performance (MP; 7-9 points), or high performance (HP; 10-12 points).
The COPD Assessment Test (CAT) assessed the health status of the patients and a threshold of ≥18 points indicated patients who were highly symptomatic.
Redefining cut-points for high symptom burden of the Global Initiative for Chronic Obstructive Lung Disease Classification in 18,577 patients with chronic obstructive pulmonary disease.
The 6MWT and incremental cardiopulmonary exercise test (Ergoselectc) were performed to determine physical capacity, both in accordance with the corresponding guidelines.
Exercise tolerance was assessed with the constant work rate test, performed at 75% of the predetermined maximal workload, during which patients cycled until symptom limitation (with a maximum test duration of 20 min).
Isokinetic quadriceps peak torque and total work of the right leg (or left leg in case of complications with the right leg) were assessed with a computerized dynamometer (Biodex Multi-joint System 3d). Patients performed a set of 30 repetitions at an angular speed of 90°/s. Reference values from Borges were used.
and consisted of 40 sessions. Patients were supervised by an interdisciplinary team, including a chest physician, respiratory nurse, dietician, occupational therapist, physiotherapist, psychologist, and social worker. The cornerstone of the patient-tailored PR program was physical exercise training consisting mainly of exercises to strengthen muscles of the upper and lower extremities, treadmill walking, stationary cycling, flexibility exercises, and daily supervised outdoor walks.
Statistical analyses were performed using SPSS statistical softwaree, v25.0. Data were presented and/or tested as appropriate. Descriptive data are presented as means ± SD, medians (interquartile 1-interquartile 3), or percentages. Baseline and delta differences between 2 groups were tested by independent t test or Mann-Whitney U test. Categorical data were tested with Fisher exact test or chi-square test of homogeneity. Differences between baseline and post-PR data were tested by paired sample t test or Wilcoxon signed-rank test, and categorical data were tested with McNemar's test or related samples marginal homogeneity test. Differences in deltas between 3 groups were tested by 1-way analysis of variance, Kruskal-Wallis test, or chi-square test of homogeneity. When a statistically significant difference was obtained, pairwise Tukey's post hoc test was performed and Bonferroni correction was applied for multiple comparisons. Because of the many statistical tests performed in this study, P≤.01 was considered significant.
both distribution-based and anchor-based techniques were used to determine MID estimates for the SPPB subtests and summary score. Four distribution-based techniques were applied: SEM=SDbaseline*; empirical rule effect size=0.08*6*SDdelta; Cohen's effect size=0.5*SDdelta; 0.5*SDbaseline.
Interobserver reliability of peripheral muscle strength tests and Short Physical Performance Battery in patients with chronic obstructive pulmonary disease: a prospective observational study.
). The SEM method could not be performed for the standing balance tests because no ICCs have been determined in patients with COPD or in older persons.
To perform anchor-based methods, at least a moderate correlation between the anchors and change in SPPB subtests or summary score (r≥0.3, P<.05)
with known MIDs and expected correlations with the change in SPPB. In the presence of a sufficient correlation, linear regression and receiver operating characteristic analyses were performed between the change in SPPB as the dependent variable and the anchors as independent variables. For the receiver operating characteristic analyses, an area under the curve >0.7 was accepted as a meaningful relationship.
MID estimates of SPPB summary score and SPPB subtests were only determined for tests that are responsive to PR on group level compared with baseline values.
Results
Of the 953 patients with COPD, 632 patients were eligible for analysis. Patients were excluded due to absence of baseline SPPB data (n=1), age younger than 40 years (n=5), and participation in the PR program for the second time (n=20). In addition, 27 patients were excluded because download of the data export showed multiple baseline values for 1 or more attributes. The exclusion of patients corresponds to the baseline study reported by Stoffels et al.
Phenotypic characteristics of patients with chronic obstructive pulmonary disease after stratification for the Short Physical Performance Battery summary score.
Furthermore, patients with missing post-PR assessment SPPB data (n=216) and a baseline SPPB summary score of 12 (n=52) were excluded.
A greater number of patients included in the study had a dyspnoea grade ≥2 and a different distribution of GOLD classification (n=632) than excluded patients (n=321; P=.002 and P=.008, respectively) (table E2, available online only at http://www.archives-pmr.org/).
Adherence and type of PR program
Adherence to the PR program was high in the included patients (completed sessions=40 sessions
). There were no differences in adherence between patients in the inpatient and outpatient programs (P=.209) or between LP, MP, and HP groups (P=.788).
Most patients participated in the inpatient PR program (61%). A larger percentage of these patients were females and experienced more severe symptoms, characterized by higher dyspnoea scores, poorer health status and pulmonary function, larger number of exacerbations and hospitalizations, and more frequent oxygen use compared with patients who participated in the outpatient program (table E3, available online only at http://www.archives-pmr.org/).
Baseline characteristics
The 632 patients with COPD had a severe degree of airflow limitation, an equal male-to-female ratio, and a normal body mass index. After stratification for SPPB summary score in LP (n=69), MP (n=300), and HP (n=263) groups, patients in the LP group were older and experienced higher levels of dyspnoea compared with the MP and HP groups. More clinical characteristics and pulmonary function data are shown in table 1.
Table 1Baseline characteristics of all patients with COPD and after stratification for SPPB summary score
Indicates a significant difference after Bonferroni post hoc correction between SPPB summary scores 7-9 and SPPB summary scores 10-12.
(n=300)
14 (12-15) (n=263)
NOTE. Data are presented as mean ± SD, median (Q1 - Q3), or percentages.
Abbreviations: BMI, body mass index; CCI, Charlson Comorbidity Index; FEV1, forced expiratory volume in the first second; FVC, forced vital capacity; mMRC, modified Medical Research Council.
Indicates a significant difference after Bonferroni post hoc correction between SPPB summary scores 0-6 and SPPB summary scores 7-9.
† Indicates a significant difference after Bonferroni post hoc correction between SPPB summary scores 0-6 and SPPB summary scores 10-12.
‡ Indicates a significant difference after Bonferroni post hoc correction between SPPB summary scores 7-9 and SPPB summary scores 10-12.
Health status, dyspnoea, body composition, symptoms of anxiety and depression, and physical status improved in all patients with COPD who participated in PR (all P<.001) (table E4, available online only at http://www.archives-pmr.org/).
After stratification for baseline SPPB summary score, significant improvements in these clinical characteristics were observed in all 3 SPPB performance groups, with the exception of the anxiety subscale of the Hospital Anxiety and Depression Scale in the LP group, which did not improve after PR (P=.020). The ∆6MWT was the greatest in the LP group (47±78 m) in comparison to the MP group (24±53 m) and the HP group (12±49 m; P<.001) (table E5, available online only at http://www.archives-pmr.org/).
Differences in changes in clinical characteristics between patients participating in the inpatient and outpatient programs are depicted in table E6 (available online only at http://www.archives-pmr.org/).
Response to PR in SPPB
The 5STS was the only SPPB subtest responsive to PR, with a median ∆5STS of −1.14 (−4.20 to −0.93) seconds in patients with COPD (P<.001). Furthermore, SPPB summary score improved significantly from 9 (8-10) to 10 (9-11) points after PR (P<.001) (fig 1).
Fig 1Box plots of the baseline and post-PR (A) SPPB summary score, (B) balance side-by-side, (C) semi-tandem, (D) tandem, (E) 4MGS, and (F) 5STS for all patients and the LP, MP, and HP group. *Indicates a significant difference at P<.01; **indicates a significant difference at P<.001. The boxes in (B) and (C) are displayed as lines at the top because almost all patients maintained the balance side-by-side and semi-tandem positions for the maximum of 10 seconds.
The baseline LP group showed improvements in balance tandem (median ∆=0.00 [0.00-10.00]s and mean ∆=3.36±4.96s), 4MGS (∆=0.81 [0.37-1.40] m/s), and 5STS (∆=−6.16 [−35.00 to 0.00]s) subtests of the SPPB after PR (all P<.001). The MP group showed a significant effect of PR on 4MGS (∆=0.06 [−0.18 to 0.33] m/s) and 5STS (∆=−2.40 [−6.40 to 0.17]s) subtests. The HP group only improved on 5STS (∆=−0.74 [−2.40 to 1.00]s, P<.001) and even showed a decline in 4MGS (∆=−0.27 [−0.44 to −0.05] m/s, P<.001). Improvements in the LP group were significant larger in contrast to MP and HP groups, which resulted in a larger increase in SPPB summary score for the LP group than the MP and HP groups (see fig 1). A maximum post-PR SPPB summary score of 12 was obtained in 23 patients in the MP group and 63 patients in the HP group.
Furthermore, baseline and post-PR proportion of patients per performance group were significantly different (P<.001). The flow and direction of this change in performance group classification is presented in figure 2.
Fig 2Sankey diagram depicting the flow and distribution of the SPPB summary score for the different performance groups at baseline and post-PR.
Because differences in the type of PR program could potentially influence the SPPB response to PR, comparisons between changes in SPPB subtests and summary scores were made for patients participating in inpatient and outpatient PR programs. Changes in SPPB subtests were not significantly different between the 2 types of PR programs, except for the change in 4MGS (outpatient=−0.2 [−0.4 to 0] m/s vs. inpatient=0.1 [−0.2 to 0.4] m/s; P<.001). However, this difference did not affect the change in SPPB summary score, which was comparable between both groups (table E7, available online only at http://www.archives-pmr.org/).
MID
Because only 5STS and SPPB summary score were responsive to PR, MID estimates were not determined for the balance tests and 4MGS. Using distribution-based techniques, the MID of the 5STS ranged between 2.19-6.33 seconds and between 0.83-0.96 points for the SPPB summary score (table 2).
Table 2Distribution-based methods to estimate the minimal important difference in 5STS and SPPB summary score in patients with COPD
Table E2Differences in baseline characteristics between included and excluded patients.
Included (n=632)
Excluded (n=321)
P Value
Age (years)
65±8 (n=632)
65±9 (n=321)
0.154
Gender (male, %)
50 (n=632)
54 (n=321)
0.373
Weight (kg)
72 (60-86) (n=630)
73 (60-86) (n=298)
0.968
BMI (kg/m2)
25 (22-30) (n=630)
25 (22-30) (n=298)
0.791
mMRC score
3 (2-3) (n=631)
2 (2-3) (n=321)
0.282
mMRC≥2 (% patients)
90 (n=631)
82 (n=321)
0.002
CAT score
22±6 (n=593)
21±7 (n=300)
0.383
CAT≥18 (% patients)
77 (n=594)
72 (n=300)
0.100
Exacerbations in the past 12 months (0/1/2/3/4/>4, % patients)
18/17/22/14/8/21 (n=627)
23/16/16/13/8/24 (n=321)
0.258
≥2 exacerbations in the past 12 months (% patients)
64 (n=627)
62 (n=321)
0.434
Hospitalizations in the past 12 months (0/1/2/3/4/>4, % patients)
53/27/9/6/2/3 (n=630)
61/22/9/6/2/0 (n=299)
0.295
≥1 hospitalization in the past 12 months (% patients)
47 (n=630)
39 (n=299)
0.064
CCI (points)
1 (1-2) (n=632)
1 (1-2) (n=321)
0.280
CCI≥2 (% patients)
45 (n=632)
42 (n=321)
0.370
Long-term O2 use (yes, % patients)
24 (n=620)
19 (n=316)
0.115
GOLD I/II/III/IV (% patients)
9/28/37/26 (n=632)
10/27/41/22 (n=320)
0.555
GOLD A/B/C/D (% patients)
3/24/7/66 (n=625)
10/28/8/54 (n=297)
0.008
FEV1 (% predicted)
43 (30-62) (n=632)
43 (32-59) (n=320)
0.691
FEV1/FVC (%)
35 (27-47) (n=632)
34 (28-48) (n=320)
0.842
Data is presented as mean ± SD, median (Q1 – Q3), or percentages. Abbreviations: BMI, body mass index; CAT, COPD Assessment Test; CCI, Charlson Comorbidity Index; FEV1, forced expiratory volume in the first second; FVC, forced vital capacity; GOLD, Global Initiative for Chronic Obstructive Lung Disease; mMRC, modified Medical Research Council.
Table E3Differences in baseline characteristics between patients following an in- and outpatient program.
Inpatient (n=387)
Outpatient (n=238)
P Value
Age (years)
66±8 (n=387)
65±8 (n=238)
0.252
Gender (male, %)
45 (n=387)
59 (n=238)
0.001
Weight (kg)
71 (59-86) (n=386)
75 (62-88) (n=237)
0.081
BMI (kg/m2)
25 (21-31) (n=386)
25 (22-30) (n=237)
0.575
mMRC score
3 (2-4) (n=387)
2 (2-3) (n=237)
<0.001
mMRC≥2 (% patients)
95 (n=387)
80 (n=237)
0.002
CAT score
23±6 (n=364)
19±6 (n=223)
<0.001
CAT≥18 (% patients)
87 (n=364)
60 (n=223)
<0.001
Exacerbations in the past 12 months (0/1/2/3/4/>4, % patients)
14/15/22/15/9/25 (n=385)
26/20/22/12/6/14 (n=235)
<0.001
≥2 exacerbations in the past 12 months (% patients)
71 (n=385)
54 (n=235)
<0.001
Hospitalizations in the past 12 months (0/1/2/3/4/>4, % patients)
48/27/10/7/3/5 (n=386)
63/26/5/3/2/1 (n=237)
<0.001
≥1 hospitalization in the past 12 months (% patients)
52 (n=386)
37 (n=237)
<0.001
CCI (points)
1 (1-2) (n=387)
1 (1-2) (n=238)
0.972
CCI≥2 (% patients)
45 (n=387)
46 (n=238)
0.741
Long-term O2 use (yes, % patients)
33 (n=379)
10 (n=234)
<0.001
GOLD I/II/III/IV (% patients)
6/23/39/32 (n=387)
13/37/35/15 (n=238)
<0.001
GOLD A/B/C/D (% patients)
1/21/4/74 (n=384)
8/29/12/51 (n=234)
<0.001
FEV1 (% predicted)
38 (28-54) (n=387)
51 (38-70) (n=238)
<0.001
FEV1/FVC (%)
33 (26-46) (n=387)
39 (31-50) (n=238)
<0.001
Data is presented as mean ± SD, median (Q1 – Q3), or percentages. Abbreviations: BMI, body mass index; CAT, COPD Assessment Test; CCI, Charlson Comorbidity Index; FEV1, forced expiratory volume in the first second; FVC, forced vital capacity; GOLD, Global Initiative for Chronic Obstructive Lung Disease; mMRC, modified Medical Research Council.
Table E4Baseline, post and delta (post minus baseline) pulmonary rehabilitation data of all patients with COPD.
Baseline
Post PR
Delta
P Value
Symptom burden and health status
mMRC score
3 (2-3) (n=591)
2 (1-2) (n=591)
-1 (-1-0) (n=591)
<0.001
mMRC≥2 (% patients)
89 (n=591)
64 (n=591)
-25 (n=591)
<0.001
CAT score
22±6 (n=560)
19±7 (n=560)
-3±6 (n=560)
<0.001
CAT≥18 (% patients)
77 (n=560)
58 (n=560)
-19 (n=560)
<0.001
Body composition
FFM index
16.5±2.5 (n=620)
17.0±2.4 (n=620)
0.4±0.6 (n=620)
<0.001
FFM legs (kg)
15.1 (12.1–17.7) (n=621)
15.5 (12.7–18.3) (n=621)
0.5 (0.0-1.1) (n=621)
<0.001
Emotional status
HADS anxiety score
7 (4-10) (n=557)
6 (3-9) (n=557)
-1 (-3-1) (n=557)
<0.001
HADS anxiety≥10 (% patients)
28 (n=557)
22 (n=557)
-6 (n=557)
0.001
HADS depression score
7 (4-10) (n=557)
5 (3-8) (n=557)
-1 (-3-0) (n=557)
<0.001
HADS depression≥10 (% patients)
30 (n=557)
16 (n=557)
-14 (n=557)
<0.001
Physical status
6MWD (m)
370±109 (n=618)
391±109 (n=618)
22±56 (n=618)
<0.001
CWRT TTE (s)
230 (166-329) (n=546)
328 (215-660) (n=546)
112 (14-347) (n=546)
<0.001
Isokinetic quadriceps peak torque (Nm)
82 (60-105) (n=456)
89 (70-115) (n=456)
9 (2-17) (n=456)
<0.001
Isokinetic quadriceps peak torque (% predicted)
61 (47-72) (n=456)
69 (56-80) (n=456)
7 (2-13) (n=456)
<0.001
Isokinetic quadriceps total work (J)
1389 (994-1836) (n=456)
1676 (1248-2109) (n=456)
247 (107-418) (n=456)
<0.001
Data is presented as mean ± SD, median (Q1 – Q3), or percentages. Abbreviations: CAT, COPD Assessment Test; CWRT, Constant Work Rate Test; FFM, Fat-free mass; HADS, Hospital Anxiety and Depression Scale; mMRC, modified Medical Research Council; TTE, Time-To-Exhaustion; 6MWD, 6-Minute Walk Test distance.
indicates a significant difference after Bonferroni post-hoc correction between the delta's of SPPB summary scores 7-9 and SPPB summary scores 10-12. Abbreviations: CAT, COPD Assessment Test; CWRT, Constant Work Rate Test; FFM, Fat-free mass; HADS, Hospital Anxiety and Depression Scale; mMRC, modified Medical Research Council; TTE, Time-To-Exhaustion; 6MWD, 6-Minute Walk Test distance.
indicates a significant difference between baseline and Post PR of p<0.001.
(n=212)
236 (112-412) (n=212)
Data is presented as mean ± SD, median (Q1 – Q3), or percentages.
indicates a significant difference between baseline and post PR of p<0.01,
indicates a significant difference between baseline and Post PR of p<0.001.
a indicates a significant difference after Bonferroni post-hoc correction between the delta's SPPB summary scores 0-6 and SPPB summary scores 7-9.
b indicates a significant difference after Bonferroni post-hoc correction between the delta's of SPPB summary scores 0-6 and SPPB summary scores 10-12.
c indicates a significant difference after Bonferroni post-hoc correction between the delta's of SPPB summary scores 7-9 and SPPB summary scores 10-12.Abbreviations: CAT, COPD Assessment Test; CWRT, Constant Work Rate Test; FFM, Fat-free mass; HADS, Hospital Anxiety and Depression Scale; mMRC, modified Medical Research Council; TTE, Time-To-Exhaustion; 6MWD, 6-Minute Walk Test distance.
indicates a significant difference between baseline and Post PR of p<0.001. Abbreviations: CAT, COPD Assessment Test; CWRT, Constant Work Rate Test; FFM, Fat-free mass; HADS, Hospital Anxiety and Depression Scale; mMRC, modified Medical Research Council; TTE, Time-To-Exhaustion; 6MWD, 6-Minute Walk Test distance.
indicates a significant difference between baseline and Post PR of p<0.001. Abbreviations: CAT, COPD Assessment Test; CWRT, Constant Work Rate Test; FFM, Fat-free mass; HADS, Hospital Anxiety and Depression Scale; mMRC, modified Medical Research Council; TTE, Time-To-Exhaustion; 6MWD, 6-Minute Walk Test distance.
indicates a significant difference between baseline and Post PR of p<0.001. Abbreviations: CAT, COPD Assessment Test; CWRT, Constant Work Rate Test; FFM, Fat-free mass; HADS, Hospital Anxiety and Depression Scale; mMRC, modified Medical Research Council; TTE, Time-To-Exhaustion; 6MWD, 6-Minute Walk Test distance.
indicates a significant difference between baseline and Post PR of p<0.001. Abbreviations: CAT, COPD Assessment Test; CWRT, Constant Work Rate Test; FFM, Fat-free mass; HADS, Hospital Anxiety and Depression Scale; mMRC, modified Medical Research Council; TTE, Time-To-Exhaustion; 6MWD, 6-Minute Walk Test distance.
indicates a significant difference between baseline and Post PR of p<0.001. Abbreviations: CAT, COPD Assessment Test; CWRT, Constant Work Rate Test; FFM, Fat-free mass; HADS, Hospital Anxiety and Depression Scale; mMRC, modified Medical Research Council; TTE, Time-To-Exhaustion; 6MWD, 6-Minute Walk Test distance.
indicates a significant difference between baseline and Post PR of p<0.001. Abbreviations: CAT, COPD Assessment Test; CWRT, Constant Work Rate Test; FFM, Fat-free mass; HADS, Hospital Anxiety and Depression Scale; mMRC, modified Medical Research Council; TTE, Time-To-Exhaustion; 6MWD, 6-Minute Walk Test distance.
indicates a significant difference between baseline and Post PR of p<0.001. Abbreviations: CAT, COPD Assessment Test; CWRT, Constant Work Rate Test; FFM, Fat-free mass; HADS, Hospital Anxiety and Depression Scale; mMRC, modified Medical Research Council; TTE, Time-To-Exhaustion; 6MWD, 6-Minute Walk Test distance.
indicates a significant difference between baseline and Post PR of p<0.001. Abbreviations: CAT, COPD Assessment Test; CWRT, Constant Work Rate Test; FFM, Fat-free mass; HADS, Hospital Anxiety and Depression Scale; mMRC, modified Medical Research Council; TTE, Time-To-Exhaustion; 6MWD, 6-Minute Walk Test distance.
indicates a significant difference between baseline and Post PR of p<0.001. Abbreviations: CAT, COPD Assessment Test; CWRT, Constant Work Rate Test; FFM, Fat-free mass; HADS, Hospital Anxiety and Depression Scale; mMRC, modified Medical Research Council; TTE, Time-To-Exhaustion; 6MWD, 6-Minute Walk Test distance.
indicates a significant difference between baseline and Post PR of p<0.001. Abbreviations: CAT, COPD Assessment Test; CWRT, Constant Work Rate Test; FFM, Fat-free mass; HADS, Hospital Anxiety and Depression Scale; mMRC, modified Medical Research Council; TTE, Time-To-Exhaustion; 6MWD, 6-Minute Walk Test distance.
indicates a significant difference between baseline and Post PR of p<0.001. Abbreviations: CAT, COPD Assessment Test; CWRT, Constant Work Rate Test; FFM, Fat-free mass; HADS, Hospital Anxiety and Depression Scale; mMRC, modified Medical Research Council; TTE, Time-To-Exhaustion; 6MWD, 6-Minute Walk Test distance.
indicates a significant difference between baseline and Post PR of p<0.001. Abbreviations: CAT, COPD Assessment Test; CWRT, Constant Work Rate Test; FFM, Fat-free mass; HADS, Hospital Anxiety and Depression Scale; mMRC, modified Medical Research Council; TTE, Time-To-Exhaustion; 6MWD, 6-Minute Walk Test distance.
indicates a significant difference between baseline and Post PR of p<0.001. Abbreviations: CAT, COPD Assessment Test; CWRT, Constant Work Rate Test; FFM, Fat-free mass; HADS, Hospital Anxiety and Depression Scale; mMRC, modified Medical Research Council; TTE, Time-To-Exhaustion; 6MWD, 6-Minute Walk Test distance.
indicates a significant difference between baseline and Post PR of p<0.001. Abbreviations: CAT, COPD Assessment Test; CWRT, Constant Work Rate Test; FFM, Fat-free mass; HADS, Hospital Anxiety and Depression Scale; mMRC, modified Medical Research Council; TTE, Time-To-Exhaustion; 6MWD, 6-Minute Walk Test distance.
indicates a significant difference between baseline and Post PR of p<0.001. Abbreviations: CAT, COPD Assessment Test; CWRT, Constant Work Rate Test; FFM, Fat-free mass; HADS, Hospital Anxiety and Depression Scale; mMRC, modified Medical Research Council; TTE, Time-To-Exhaustion; 6MWD, 6-Minute Walk Test distance.
indicates a significant difference between baseline and Post PR of p<0.001. Abbreviations: CAT, COPD Assessment Test; CWRT, Constant Work Rate Test; FFM, Fat-free mass; HADS, Hospital Anxiety and Depression Scale; mMRC, modified Medical Research Council; TTE, Time-To-Exhaustion; 6MWD, 6-Minute Walk Test distance.
indicates a significant difference between baseline and Post PR of p<0.001. Abbreviations: CAT, COPD Assessment Test; CWRT, Constant Work Rate Test; FFM, Fat-free mass; HADS, Hospital Anxiety and Depression Scale; mMRC, modified Medical Research Council; TTE, Time-To-Exhaustion; 6MWD, 6-Minute Walk Test distance.
indicates a significant difference between baseline and Post PR of p<0.001. Abbreviations: CAT, COPD Assessment Test; CWRT, Constant Work Rate Test; FFM, Fat-free mass; HADS, Hospital Anxiety and Depression Scale; mMRC, modified Medical Research Council; TTE, Time-To-Exhaustion; 6MWD, 6-Minute Walk Test distance.
indicates a significant difference between baseline and Post PR of p<0.001. Abbreviations: CAT, COPD Assessment Test; CWRT, Constant Work Rate Test; FFM, Fat-free mass; HADS, Hospital Anxiety and Depression Scale; mMRC, modified Medical Research Council; TTE, Time-To-Exhaustion; 6MWD, 6-Minute Walk Test distance.
indicates a significant difference between baseline and Post PR of p<0.001. Abbreviations: CAT, COPD Assessment Test; CWRT, Constant Work Rate Test; FFM, Fat-free mass; HADS, Hospital Anxiety and Depression Scale; mMRC, modified Medical Research Council; TTE, Time-To-Exhaustion; 6MWD, 6-Minute Walk Test distance.
indicates a significant difference between baseline and Post PR of p<0.001. Abbreviations: CAT, COPD Assessment Test; CWRT, Constant Work Rate Test; FFM, Fat-free mass; HADS, Hospital Anxiety and Depression Scale; mMRC, modified Medical Research Council; TTE, Time-To-Exhaustion; 6MWD, 6-Minute Walk Test distance.
indicates a significant difference between baseline and Post PR of p<0.001. Abbreviations: CAT, COPD Assessment Test; CWRT, Constant Work Rate Test; FFM, Fat-free mass; HADS, Hospital Anxiety and Depression Scale; mMRC, modified Medical Research Council; TTE, Time-To-Exhaustion; 6MWD, 6-Minute Walk Test distance.
indicates a significant difference between baseline and Post PR of p<0.001. Abbreviations: CAT, COPD Assessment Test; CWRT, Constant Work Rate Test; FFM, Fat-free mass; HADS, Hospital Anxiety and Depression Scale; mMRC, modified Medical Research Council; TTE, Time-To-Exhaustion; 6MWD, 6-Minute Walk Test distance.
indicates a significant difference between baseline and Post PR of p<0.001. Abbreviations: CAT, COPD Assessment Test; CWRT, Constant Work Rate Test; FFM, Fat-free mass; HADS, Hospital Anxiety and Depression Scale; mMRC, modified Medical Research Council; TTE, Time-To-Exhaustion; 6MWD, 6-Minute Walk Test distance.
indicates a significant difference between baseline and Post PR of p<0.001. Abbreviations: CAT, COPD Assessment Test; CWRT, Constant Work Rate Test; FFM, Fat-free mass; HADS, Hospital Anxiety and Depression Scale; mMRC, modified Medical Research Council; TTE, Time-To-Exhaustion; 6MWD, 6-Minute Walk Test distance.
indicates a significant difference between baseline and Post PR of p<0.001. Abbreviations: CAT, COPD Assessment Test; CWRT, Constant Work Rate Test; FFM, Fat-free mass; HADS, Hospital Anxiety and Depression Scale; mMRC, modified Medical Research Council; TTE, Time-To-Exhaustion; 6MWD, 6-Minute Walk Test distance.
(n=183)
234 (119-383) (n=183)
0.764
Data is presented as mean ± SD, median (Q1 – Q3), or percentages.
indicates a significant difference between baseline and post PR of p<0.01,
indicates a significant difference between baseline and Post PR of p<0.001.Abbreviations: CAT, COPD Assessment Test; CWRT, Constant Work Rate Test; FFM, Fat-free mass; HADS, Hospital Anxiety and Depression Scale; mMRC, modified Medical Research Council; TTE, Time-To-Exhaustion; 6MWD, 6-Minute Walk Test distance.
Table E7Baseline, post PR and delta (post PR minus baseline) data of the SPPB subtests and summary score in patient following an in- or outpatient program.
indicates a significant difference between baseline and Post PR of p<0.001. Abbreviations: 4MGS: 4-meter gait speed, 5STS: 5-repetition sit-to-stand, SPPB: Short Physical Performance Battery.
indicates a significant difference between baseline and Post PR of p<0.001. Abbreviations: 4MGS: 4-meter gait speed, 5STS: 5-repetition sit-to-stand, SPPB: Short Physical Performance Battery.
indicates a significant difference between baseline and Post PR of p<0.001. Abbreviations: 4MGS: 4-meter gait speed, 5STS: 5-repetition sit-to-stand, SPPB: Short Physical Performance Battery.
indicates a significant difference between baseline and Post PR of p<0.001. Abbreviations: 4MGS: 4-meter gait speed, 5STS: 5-repetition sit-to-stand, SPPB: Short Physical Performance Battery.
indicates a significant difference between baseline and Post PR of p<0.001. Abbreviations: 4MGS: 4-meter gait speed, 5STS: 5-repetition sit-to-stand, SPPB: Short Physical Performance Battery.
indicates a significant difference between baseline and Post PR of p<0.001. Abbreviations: 4MGS: 4-meter gait speed, 5STS: 5-repetition sit-to-stand, SPPB: Short Physical Performance Battery.
1 (0-2)
0.092
Data is presented as median (Q1 – Q3).
indicates a significant difference between baseline and post PR of p<0.01,
indicates a significant difference between baseline and Post PR of p<0.001.Abbreviations: 4MGS: 4-meter gait speed, 5STS: 5-repetition sit-to-stand, SPPB: Short Physical Performance Battery.
Furthermore, the change in 6MWT and CAT was not correlated or only weakly correlated with the change in 5STS and SPPB summary score and could therefore not be used as reliable anchors to determine the MIDs (table E8, available online only at http://www.archives-pmr.org/).
Table E8Correlations between change in CAT score and 6MWT (m) with the change in 5STS and SPPB summary score for patients with COPD.
∆CAT score
∆6MWT (m)
Correlation Coefficient
P Value
Correlation Coefficient
P Value
∆5STS (s)
0.084
0.047
-0.120
0.003
∆SPPB summary score
-0.151
<0.001
0.183
<0.001
Abbreviations: CAT, COPD Assessment Test; SPPB, short physical performance battery; 5STS, 5-repetition sit-to-stand; 6MWT, 6-minute walk test
Generally, the SPPB subtest 5STS and the SPPB summary score are responsive to PR in patients with COPD. In patients with a low performance at baseline, balance tandem and 4MGS are responsive to PR as well. Based on distribution-based calculations, the MID estimates range between 2.19-6.33 seconds for 5STS and 0.83-0.96 points for SPPB summary score.
In accordance with previous studies, 5STS and SPPB summary score were responsive to PR in patients with COPD.
have reported that patients with a better baseline 4MGS were less responsive to PR than patients with a worse baseline 4MGS. Furthermore, only the LP group improved balance tandem time after PR but had a change of 0 (0-10) seconds (or mean change of 3.36±4.96s), which makes the clinical significance of the improvement questionable. No performance group showed an effect of PR in balance side-by-side or semi-tandem. Although balance impairments are common in patients with COPD,
most participants were able to complete the balance tests without difficulty. These results imply that standing balance tests are less useful and effective and perhaps not adequality sensitive in evaluating the effectiveness of PR in patients with COPD, suggesting the use of more complex balance tests like Berg Balance Scale or Balance Evaluation Systems Test.
The mean 5STS MID estimates (2.19-6.33s) are larger than the MID estimate by Jones et al (1.7s) in patients with COPD after an 8-week outpatient PR program in the United Kingdom.
The current SPPB summary score MID estimates (0.83-0.96 points) are comparable with the study of Perera et al, who reported a small meaningful change of 0.5 points and a substantial change of 1.0 point for SPPB summary scores in older patients.
Because the SPPB summary score is reported in whole numbers, it seems reasonable to conclude that an improvement of 1 point on the SPPB summary score can be taken as the MID in patients with COPD after PR. This MID can be interpreted and applied at individual and group levels to determine whether patients improve after PR.
Study limitations
Analyses were performed on a selected population of patients with COPD referred for PR. Including a more diverse group of patients could complicate the interpretation of results and conclusions. These results should be applied with caution in other populations or settings, because differences in interventions, context, and population characteristics are known to influence the response and MID estimates.
In addition, 86 patients achieved a maximum post-PR SPPB score of 12, which could indicate a ceiling effect.
Inpatient and outpatient PR programs were combined in the analyses performed in this study. Although the Δ SPPB summary score was comparable between groups, differences were found in other attributes, which partly may be explained by differences at baseline. Indeed, patients with the most severe limitations participated in the inpatient program. Furthermore, due to the retrospective design, it was not possible to regain details of the actual content of the program.
Despite the intent to use anchor- and distribution-based methods to calculate MID estimates, only distribution-based calculations could be performed. Therefore, the obtained MIDs provide no clinical significance but statistical significance only. It is highly recommended that multiple anchor-based approaches be used in future MID estimations, such as the incremental shuttle walk test or patient's self-reported improvement, which were used in previous studies.
The SPPB subtest 5STS and summary score are both responsive to PR in patients with COPD after PR. The balance tandem test and 4MGS are only responsive to PR in patients with COPD with a low performance at baseline. Based on distribution-based calculations, an MID estimate of 1 point for the SPPB summary score is recommended in patients with COPD. Future research is needed to confirm MID estimates for the SPPB in different centers using anchor-based methods as well.
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Acknowledgment
We thank Prof. Wim Derave (Ghent University) for his input and collaboration within the BASES Consortium, in the context of which the current article was written.
References
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The BASES Consortium is supported by the Lung Foundation, the Netherlands (grant no. 5.1.18.232).
Disclosures: Jana De Brandt is funded by the Flemish government. The Research of Fonds Wetenschappelijk Onderzoek (FWO) Aspirant Jana De Brandt is sponsored by an FWO grant (grant no. 11B4718N). Frits M. Franssen is supported by grants and personal fees from AstraZeneca, personal fees from Boehringer Ingelheim, personal fees from Chiesi, personal fees from GlaxoSmithKline, grants and personal fees from Novartis, and personal fees from TEVA, outside the submitted work. Bram van den Borst is supported by personal lecture fees from AstraZeneca and Boehringer Ingelheim. Anouk A. Stoffels, Jana De Brandt, Roy Meys, Hieronymus W. van Hees, Anouk W. Vaes, Peter Klijn, Maurice J. Sillen, Daisy J. Janssen, Chris Burtin, and Martijn A. Spruit have nothing to disclose.
The article by Stoffels et al, Short Physical Performance Battery: Response to Pulmonary Rehabilitation and Minimal Important Difference Estimates in Patients With Chronic Obstructive Pulmonary Disease, published in Archives of Physical Medicine and Rehabilitation 2021; 102(12), p2283-2496, https://www.archives-pmr.org/article/S0003-9993(21)00452-4/fulltext , contained errors. There was a mistake in the transformation of the post-pulmonary rehabilitation (PR) 4-meter gait speed (4MGS) test time (s) to speed (m/s).
Indicates a significant difference after Bonferroni post hoc correction between SPPB summary scores 0-6 and SPPB summary scores 7-9.
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