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

Abstract

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 (ICC2.1) = 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.

Reproducibility of Cadence-Free 6-Minute Step Test in Subjects with COPD

“…This indicates that, for this population, the test is reproducible with reproducibility values similar to those obtained using other clinical exercise tests, such as 6-min walk test, which presents an ICC of 0.88 -0.94, [20][21][22] and shuttle-walk test, which presents an ICC of 0.87. 23 Moreover, the error value for this comparison was acceptable, presenting a mean error of 5.7 steps and limits of agreement ranging from Ϫ7.1 to 18.6 steps.…”

“…Standard error of measurement as a percentage of the mean was 5%, which was similar to the same error analysis using the 6-min walk test in other studies that also represented ϳ5% of the mean performance of the test. 21,25 These results show that the performance in this test was not influenced by the learning effect in the COPD population, which leads to the affirmation that this test can be done without a familiarization test, spending only 15 min of assessment time. This characteristic could be an advantage over the 6-min walk test, which requires at least one previous test and a recovery time between them, totaling a time expenditure of at least 50 min.…”

“…The expected ICC value used was consistent with the mean value of ICC found in 6 min walk test reproducibility studies: 0.88 -0.94. [20][21][22] …”

Measuring Gait Speed in the Out-Patient Clinic: Methodology and Feasibility

“…Our group had better test-retest reliability for the usual 10-meter gait speed (ICC of 0.97 vs 0.87) when comparing with the usual 30-meter gait speed measured in a smaller COPD cohort. 14 This study showed that in patients with COPD, there is good agreement between stopwatch and automated timing system measurements for usual gait speed measurements. That agreement did not hold true with maximal walking speeds.…”

“…12,13 However, those studies did not evaluate the several commonly described gait speed protocols and have not established the effect of distance walked, pace, or timing methods on the reliability and reproducibility of gait speed results in patients with COPD. Prior studies using fast pace 14,15 have not investigated the commonly used distances (4 and 10 meters) or the possible timing systems. Variability in the methodology is believed to affect clinical interpretation and implementation of the gait speed measures.…”