Chest
Volume 146, Issue 1, July 2014, Pages 104-110
Journal home page for Chest

Original Research
COPD
Determinants of Gait Speed in COPD

https://doi.org/10.1378/chest.13-2017Get rights and content

BACKGROUND

Measures of physical function, daily physical activity, and exercise capacity have been proposed for the care of patients with COPD but are not used routinely in daily office care. Gait speed is a powerful and simple measure of physical function in elderly patients and seems to be a promising measure for the daily care of patients with COPD. The objective of this study was to comprehensively evaluate the determinants and factors influencing gait speed in COPD, particularly the association of gait speed with objectively measured physical activity and the most used exercise capacity field test in cardiopulmonary disease: the 6-min walk test (6MWT).

METHODS

One hundred thirty patients with stable COPD performed two different 4-m gait speed protocols (usual and maximal pace). We modeled gait speed using demographics, lung function, dyspnea, quality of life, physical activity monitoring, exercise capacity, mood, cognitive function, and health-care use.

RESULTS

Gait speed was independently associated with 6MWT but not with daily physical activity. The correlation between gait speed and 6MWT was high regardless of protocol used (r = 0.77-0.80). Both 6MWT and gait speed shared similar constructs. Gait speed had an excellent ability to predict poor (≤ 350 m) or very poor (≤ 200 m) 6MWT distances (areas under the curve, 0.87 and 0.98, respectively). Gait speed was not independently associated with quality of life, mood, or cognitive function.

CONCLUSIONS

Gait speed is more indicative of exercise capacity (6MWT) than daily physical activity in COPD. Despite its simplicity, gait speed has outstanding screening properties for detecting poor and very poor 6MWT performance, making it a useful and informative tool for the clinical care of patients with COPD.

Section snippets

Subjects

Patients were prospectively recruited from an outpatient pulmonary clinic. Inclusion criteria were (1) a diagnosis of COPD based on the GOLD (Global Initiative for Chronic Obstructive Lung Disease) 2011 guidelines,15 (2) age ≥ 18 years, and (3) ability to complete questionnaires. Patients were excluded if they had an unstable respiratory condition 1 month prior to the study or if they had a walking limitation from a significant orthopedic or neurologic disease (limited by pain, unsteadiness, or

Results

Baseline demographics for the 130 participants enrolled are shown in Table 1. The severity of COPD was moderate to severe, and on the basis of the combined GOLD COPD assessment,30 58 participants (45%) were in group D, 25 (19%) in group C, 16 (12%) in group B, and 31 (24%) in group A. The average gait speeds were 1.11 ± 0.25 m/s for usual pace and 1.63 ± 0.38 m/s for maximal pace. Eighty-five participants were able to wear the activity monitors for the required time. There were no differences

Discussion

The main finding of this study is that gait speed is not independently associated with objectively measured daily physical activity in COPD but is strongly and independently associated with exercise capacity as measured by 6MWT, regardless of pace instructions (maximal or usual gait speed). We found that gait speed may be an easy-to-use and clinically relevant screening tool for poor and very poor exercise capacity in routine COPD office practice. The gait speed benchmarks of 0.9 and 0.8 m/s

Conclusions

Gait speed may be used as a screening measure of poor exercise capacity but is not informative of daily physical activity in COPD. Usual 4-m gait speed is a simple measure with a similar construct as 6MWT and is accurate in detecting poor and very poor 6MWT, which makes it a powerful and informative tool in the routine clinical care of COPD.

Acknowledgments

Author contributions: R. P. B. served as principal investigator, had full access to all of the data in the study, and takes responsibility for the integrity of the data and the accuracy of the data analysis. C. K., Z. S. D., N. K. L., and R. P. B. contributed to study design; C. K. and R. P. B. contributed to data collection; C. K., Z. S. D., and R. P. B. contributed to data analysis; P. J. N. contributed to statistical analysis; and C. K., Z. S. D., N. K. L., P. J. N., and R. P. B. contributed

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    Part of this article has been presented in poster form at the American Thoracic Society International Conference, May 17-22, 2013, Philadelphia, PA.

    FUNDING/SUPPORT: This work was supported by the National Heart, Lung, and Blood Institute of the National Institutes of Health [Grant 5R01HL094680-05 to Dr Benzo].

    Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.

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