Reproducibility and Sensitivity of the 6-Minute Stepper Test in Patients with COPD.

The aims of this study were to test the reproducibility of the 6-minute stepper test (6MST), and evaluate its accuracy in detecting improved functional capacity after pulmonary rehabilitation (PR) in patients with chronic obstructive pulmonary disease (COPD). Thirty-five COPD outpatients performed two 6MSTs in the same session, before (6MST1 and 6MST2) and after (6MST3 and 6MST4) PR. The performance, perceived exertion, heart rate and arterial oxygen saturation were measured during each 6MST. The performance was higher during the second 6MST of the same session (before PR: 514 strokes during the 6MST2 > 471 strokes during the 6MST1, and after PR: 559 strokes during the 6MST4 > 508 strokes during the 6MST3; p = 0.04). After PR, 6MST performance was higher than before PR (6MST3 > 6MST1 and 6MST4 > 6MST2; P < 0.01). The bias (the difference in the number of strokes) between the two 6MSTs from the same session (before PR: 6MST2-6MST1 = 42 strokes vs after PR: 6MST4-6MST3 = 52 strokes) was not different (P = 0.34). However, both bias were greater than 0 (P < 0.001). The mean performances for the two 6MSTs of the same session (before PR: 6MST1 and 6MST2 and after PR: 6MST3 and 6MST4) were correlated with the bias between these performances (P < 0.01; r = 0.32). The perceived exertions were lower after PR (P < 0.02). The systematic improvement of performance (8-10%) during the second 6MST of the each session may be explained from the warming of hydraulic jacks of the stepper and/or learning effect. On the other hand, the 6MST seems sufficiently sensitive to detect functional capacity improvements after PR in patients with COPD.

An original field evaluation test for chronic obstructive pulmonary disease population: the six-minute stepper test.

PURPOSE: The aim of this study was to evaluate a new field test, the six-minute stepper test (6-MST), by studying its reproducibility, sensitivity and validity. METHODS: After a familiarization test, 16 patients with chronic obstructive pulmonary disease (COPD) and 15 healthy subjects performed two six-minute stepper tests per day over three evaluation days. Ten of the 16 patients with COPD also performed a six-minute walking test (6-MWT) with an analysis of gas exchange to compare the metabolic requirements of the two tests. Dyspnoea Borg values were evaluated with Borg's CR-10 scale. RESULTS: The mean (SD) scores for the COPD group for the first and second six-minute stepper tests were 382.49 (106.01) and 412.45 (118.39) strokes/6 minutes, respectively. Crossed comparison between the first or the second six-minute stepper tests of each evaluation day revealed no significant difference, indicating the reproducibility of the test. The sensitivity was demonstrated by a significantly higher performance in the healthy group (P < 0.001), demonstrating the ability of the test to detect two groups with different fitness levels. Finally, mean dyspnoea Borg values (SD) were significantly lower (P < 0.05) during the six-minute stepper test than during 6-MWT (2.5 (1.5) versus 3.1 (1.2)). CONCLUSIONS: This study demonstrated that the six-minute stepper test is a reproducible, sensitive, secure, well-tolerated and feasible test for patients with COPD. The reproducibility and sensitivity of the six-minute stepper test suggests that this test could be used in the evaluation of exercise tolerance in patients with COPD.