The Six-Minute Walk (6MWT) as a measure Walking capacity (WC) in Ambulatory Individual with Amyotrophic Lateral Sclerosis (ambALS)

Publication date: Available online 30 April 2017
Source:Archives of Physical Medicine and Rehabilitation
Author(s): Mohammed Sanjak, Velma Langford, Scott Holsten, Nigel Rozario, Charity G. Moore Patterson, Elena Bravver, William L. Bockenek, Benjamin R. Brooks
ObjectiveTo determine the validity of the 6MWT as an outcome measure to evaluate WC in ambALS.Design: Observational study. Participants performed 6MWT, 25FWT, TUG, lower extremity maximum voluntary isometric contraction (MVIC), ALSFRS-R, and forced vital capacity (FVC).SettingMultidisciplinary ALS clinic at an academic medical center.Participants: AmbALS (N=186) who ambulate without (stage I) or with (stage II) assistive device.Interventions: Not applicable.Main outcome measures: Walking distance obtained from 6MWT.ResultsWC was reduced to 66% predicted of normal controls [75.2% ± 22 in stage I, and 42.6% ± 22 in stage II]. The 6MWT correlated with all other outcome measures in ambALS [25FWT (r=-0.74, p≤0.0001), TUG (r=-0.80, p≤0.0001), MVIC (r=0.64, p≤0.0001), percentage of predicted FVC (FVC%) (r=0.25, p≤0.0007), ALSFRS-R (r=0.52, p≤0.0001), and ALSFRS-GM (r=0.71, p≤0.0001)]. When ambALS were stratified by stage of ambulation, the 6MWT was associated with all other outcome measures in stage I [25FWT (r=-0.56, p≤0.0001), TUG (r=-0.66, p≤0.0001), MVIC (r=0.51, p≤0.0001), FVC% (r=0.40, p≤0.02), ALSFRS-R (r=0.52, p≤0.0001), and ALSFRS-R-GM (r=0.61, p≤0.0001)]. In stage II, the 6MWT correlated with 25FWT (r=-0.83, p≤0.0001), TUG (r=-0.77, p≤0.0001), MVIC (r=0.47, p≤0.0001), and ALSFRS-GM (r=0.61, p≤0.0001), but not with FVC% (r=0.09, p≤0.513) or ALSFRS-R (r=0.21, p≤0.141).resultsConclusionsThe 6MWT is a valid measure of WC of ambALS that is associated with measures of lower extremity muscle strength and function in both stages of ambulation. The discordance between the 6MWT with the ALSFRS-R and FVC% in stage II ambALS indicates that the 6MWT is an independent measure of ambulatory function in both stages of ambulation. The 6MWT may provide a quantitative, simple, and inexpensive outcome measure of WC for early stage clinical trials in ambALS.conclusion



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