Background

Functional capacity assessment is important in patients with chronic obstructive pulmonary disease (COPD). It can be performed by the six-minute walk test (6MWT) on a 30-meter track. However, such space is not always available in clinical settings.

Objectives

To compare the performance between the 6MWT on a 30- (6MWT₃₀) and 20-meter (6MWT₂₀) track; to evaluate the validity and reliability of the 6MWT₃₀ and the 6MWT₂₀; and to determine for which patients track length has the greatest impact on performance.

Methods

Patients with COPD randomly performed two 6MWT₃₀ and two 6MWT₂₀ on two different days and were also assessed using the COPD Assessment Test (CAT) and modified Medical Research Council (mMRC) scale.

Results

Thirty patients (23 men; mean ± standard deviation FEV₁%pred: 45.6 ± 12.1) participated in the study. They walked a greater distance on the 6MWT₃₀ than on the 6MWT₂₀ [mean difference: 22.1 m (95% CI: 12, 32 m)]. The longer the 6MWT₃₀ distance, the greater the difference between the 2 tests (r = 0.51; p = 0.004). The 6MWT₂₀ showed high reliability [ICC: 0.96 (95% CI: 0.77, 0.99)] and the results were associated with the distance walked on the 6MWT₃₀ (r = 0.86), CAT (r = −0.53), and mMRC (r = −0.62). Patients who walked ≥430 m in the 6MWT₃₀ presented a difference between the tests greater than those who walked <430 m (34.5 ± 23.3 m vs. 12.6 ± 24.1 m; respectively; p = 0.01).

Conclusions

Performance was higher on the 6MWT₃₀, with the difference increasing as performance improved. Therefore, the 6MWT₂₀ is valid and reliable to evaluate functional capacity but should not be considered interchangeable with the 6MWT₃₀, especially for the less disabled patients with COPD.

中文翻译：

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慢性阻塞性肺病患者在 20 米和 30 米跑道上进行六分钟步行测试时的表现差异：有效性和可靠性。

 背景

功能能力评估对于慢性阻塞性肺疾病（COPD）患者很重要。可以通过30米跑道上的六分钟步行测试（6MWT）来进行。然而，这样的空间在临床环境中并不总是可用。

 目标

比较 6MWT 在 30 米（6MWT ₃₀ ）和 20 米（6MWT ₂₀ ）轨道上的性能；评估6MWT ₃₀和6MWT ₂₀的有效性和可靠性；并确定哪些患者的轨迹长度对表现影响最大。

 方法

COPD 患者在不同的两天随机进行两次 6MWT ₃₀和两次 6MWT ₂₀ ，并使用 COPD 评估测试 (CAT) 和改良医学研究委员会 (mMRC) 量表进行评估。

 结果

30 名患者（23 名男性；FEV ₁ %pred 平均值 ± 标准差：45.6 ± 12.1）参与了该研究。他们在 6MWT ₃₀上行走的距离比在 6MWT ₂₀上行走的距离更长 [平均差：22.1 m (95% CI: 12, 32 m)]。 6MWT ₃₀距离越长，两次测试之间的差异就越大（r = 0.51；p = 0.004）。 6MWT ₂₀显示出高可靠性 [ICC：0.96（95% CI：0.77, 0.99）]，结果与 6MWT ₃₀上行走的距离 (r = 0.86)、CAT (r = -0.53) 和 mMRC 相关（ r = -0.62）。在 6MWT ₃₀中行走 ≥430 m 的患者在测试之间的差异大于行走 <430 m 的患者（分别为 34.5 ± 23.3 m 与 12.6 ± 24.1 m；p = 0.01）。

 结论

6MWT ₃₀的性能更高，并且随着性能的提高，差异也越来越大。因此，6MWT ₂₀对于评估功能能力是有效且可靠的，但不应被认为与 6MWT ₃₀可以互换，特别是对于残疾程度较低的 COPD 患者。