Are the 10 meter and 6 minute walk tests redundant in patients with spinal cord injury?

Gail F Forrest,Jeffrey J Buehner,Karen Hutchinson,Sue Ann Sisto,D Michele Basso,Leslie R Vanhiel,Douglas J Lorenz,Michael Fehlings

doi:10.1371/journal.pone.0094108

Abstract

ObjectiveTo evaluate the relationship and redundancy between gait speeds measured by the 10 Meter Walk Test (10MWT) and 6 Minute Walk Test (6MWT) after motor incomplete spinal cord injury (iSCI). To identify gait speed thresholds supporting functional ambulation as measured with the Spinal Cord Injury Functional Ambulation Inventory (SCI-FAI).DesignProspective observational cohort.SettingSeven outpatient rehabilitation centers from the Christopher and Dana Reeve Foundation NeuroRecovery Network (NRN).Participants249 NRN patients with American Spinal Injury Association Impairment Scale (AIS) level C (n = 20), D (n = 179) and (n = 50) iSCI not AIS evaluated, from February 2008 through April 2011.InterventionsLocomotor training using body weight support and walking on a treadmill, overground and home/community practice.Main Outcome Measure(s)10MWT and 6MWT collected at enrollment, approximately every 20 sessions, and upon discharge.ResultsThe 10MWT and 6MWT speeds were highly correlated and the 10MWT speeds were generally faster. However, the predicted 6MWT gait speed from the 10MWT, revealed increasing error with increased gait speed. Regression lines remained significantly different from lines of agreement, when the group was divided into fast (≥0.44 m/s) and slow walkers (<0.44 m/s). Significant differences between 6MWT and 10MWT gait speeds were observed across SCI-FAI walking mobility categories (Wilcoxon sign rank test p<.001), and mean speed thresholds for limited community ambulation differed for each measure. The smallest real difference for the 6MWT and 10MWT, as well as the minimally clinically important difference (MCID) values, were also distinct for the two tests.ConclusionsWhile the speeds were correlated between the 6MWT and 10MWT, redundancy in the tests using predictive modeling was not observed. Different speed thresholds and separate MCIDs were defined for community ambulation for each test.

Highlights

In people with incomplete spinal cord injury, walking capacity - comprised of walking speed and endurance - is an important construct in evaluating efficacy of gait training rehabilitation[1]
Significant differences between 6 Minute Walk Test (6MWT) and 10 Meter Walk Test (10MWT) gait speeds were observed across Spinal Cord Injury Functional Ambulation Inventory (SCI-FAI) walking mobility categories (Wilcoxon sign rank test p,.001), and mean speed thresholds for limited community ambulation differed for each measure
Different speed thresholds and separate minimally clinically important difference (MCID) were defined for community ambulation for each test

Summary

Introduction

In people with incomplete spinal cord injury (iSCI), walking capacity - comprised of walking speed and endurance - is an important construct in evaluating efficacy of gait training rehabilitation[1]. The most accepted standardized timed tests used in studies of persons with iSCI are the 10 Meter Walk Test (10MWT) for speed and 6 Minute Walk Test (6MWT) for walking endurance[2]. These outcome measures are valid, reliable and responsive for acute to chronic iSCI[3]. When higher speeds were attained, the two walking tests produced significantly different values from each other These differences were postulated to be clinically irrelevant, because subjects were all independent ambulators and considered to have sufficient capacity to perform unrestricted community walking, the community ambulation scores were not reported. Speed thresholds for community ambulation after iSCI been described for the 10MWT[11] they have yet to be identified for the 6MWT

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