Walking Speed Provides Functional Benchmarks in MS

Pauline Anderson

October 30, 2013

A new study finds that a functional benchmark — walking 25 feet in more than 6 to 8 seconds — provides useful information on the occupational and ambulatory status of patients with multiple sclerosis (MS).

Researchers showed that patients with MS who take longer than 6 seconds to complete the Timed 25-Foot Walking (T25FW) test are more likely to be unemployed, use a cane, and need assistance with daily activities than those who can walk this distance more quickly, and that a speed of 8 seconds or longer could mean facing additional social, occupational, and ambulatory difficulties.

These walking benchmarks can be used as research tools or for drug development, especially now that the field of MS is moving quickly and hope for reparative therapies is growing, said lead author Myla D. Goldman, MD, director, James Q. Miller Multiple Sclerosis Clinic, University of Virginia, Charlottesville.

"Being able to identify a measure that ties very closely and in a meaningful way to what patients are experiencing in their everyday life has tremendous value," Dr. Goldman told Medscape Medical News. "This will allow us to understand the real-world impact of our treatments as we test them on these populations."

The T25FW is a "quick and simple" assessment that can easily be done in the clinic, added Dr. Goldman.

This new study is published online October 30 in Neurology.

Anchor Categories

The T25FW score, reported in seconds, is averaged over 2 consecutive walks. Research suggests that a more than 20% change in T25FW is statistically significant and clinically meaningful, but what has remained unclear is how the score relates to an individual's life and function.

The study had 2 phases. The benchmark identification step included 159 patients with relapsing or progressive MS and a T25FW test performed during routine clinical care in the previous 15 months who completed a detailed mail-in survey that included various performance scales. This group was 68% women and had an average age of 48 years. The median T25FW time in this survey responder group was 5.4 seconds.

Researchers grouped these patients according to "real life" anchor categories, such as marital and employment status, government healthcare, and mobility assistance. They found that 45% of respondents were employed and 37% described themselves as disabled.

The researchers found that a T25FW time of 6 to 7.99 seconds was associated with a change in occupation due to MS, disabled by self-report, requiring assistance with instrumental activities of daily living (IADLs), cane use for outside walking, and "early cane use" on mobility performance scale (PS).

"At 6 seconds, we see an increase in unemployment and we also see an increase in individuals who had to make a change in occupation due to MS," commented Dr. Goldman. "So we see the 6 second group is struggling."

Although the 6-second cutoff saw a significant drop in terms of walking out in the community, patients in this category were still doing activities at home, such as preparing meals or doing laundry, added Dr. Goldman.

However, a test time of 8 seconds or more was associated with permanent disability, government healthcare assistance, change in occupational status due to MS, inability to perform IADLs, and use of a walker.

In terms of T25FW scores and percentage differences between real-life categories, the study found a 28% difference associated with "change in occupation due to MS" (no vs yes). T25FW performance correlated with a patient's self-report of disability on the PS; the strongest relationship was between T25FW and PS-Mobility (P < .001).

With use of a measure of IADL, T25FW performance differed on average by 43% between those who required "no help" vs "some help." There was an overall statistically significant relationship between T25FW and IADL scores (P < .0001).

"The identification step supported a T25FW performance of ≥6 seconds (6-7.99) and ≥ 8 seconds to represent clinically significant benchmarks of MS-related gait impairment," the authors write.

Validation Phase

The researchers validated these T25FW benchmarks in a separate group of 95 patients with confirmed MS, and an average age of 52.7 years. In a single 2-hour session, this benchmark validation group completed testing which included the Expanded Disability Status Scale (EDSS) and the T25FW. The median EDSS score was 4.5 and the median T25FW time was 6.0 seconds.

On the T25FW test, about half of this group had a time of less than 6 seconds, 22% had a time of 6 to 7.99 seconds, and 28% had a time of 8 or more seconds. The researchers found group main effects on 12 of 13 objective and subjective measures (P < .05).

In patients with T25FW times of less than 6 seconds, there were significant group differences for some assessments, most notably in the MS Walking Scale and the PS Mobility.

"We found that with 5 to 5.99 seconds, there are individuals who are already struggling," commented Dr. Goldman. "About a third have some trouble preparing a meal, have some trouble with employment, so it's an indicator that in that range we are starting to see some difficulties."

And for those who take longer than 10 seconds to walk the 25 feet, "we need more data looking at people in that upper range" to see what changes in functions or abilities this relates to, added Dr. Goldman."We need more information looking at a larger group of people to make sure that we really understand these benchmarks and to identify whether there are different benchmarks that are informative about patients' lives at home."

Easy Administration

The T25FW test, which was developed as part of an MS Functional Composite outcome measure, is faster, more portable, and easier to administer than the EDSS, which involves a full neurologic exam that can take 20 to 30 minutes, according to Dr. Goldman. Another advantage of the T25FW is that it can be administered by any trained person, not necessarily a doctor.

With the T25FW, "you can garner a tremendous amount of information about what may be happening for patients in their personal life and related to their everyday functional independence," said Dr. Goldman.

But according to the study authors, physicians are not currently as familiar with the T25FW as they are with the EDSS.

Asked to comment, Christopher Bever, MD, professor, neurology, University of Maryland Medical Center, Baltimore, and a member of the American Academy of Neurology, said the study results "will encourage more people to include this test as part of a standard assessment of MS patients when they come into the clinic."

"It's useful to have some idea of what patients look like based on a particular score they have on the test," added Dr. Bever.

However, Dr. Bever noted that the study was cross-sectional and although it found statistical associations, these can't be used to conclude, for example, that a patient with a time of 8 seconds on the T25FW is necessarily receiving Social Security or disability benefits.

Dr. Bever agreed that as part of the MS Functional Composite, the T25FW is already fairly widely used in clinical trials and is easy to use in the clinic; the examiner can just mark off a 25-foot space in a hallway and use a stop watch or watch with a second hand.

He noted that the T25FW is more sensitive than the EDSS. "There's a need for sensitive measures that specifically relate to walking because walking is so important to MS patients, and while EDSS is heavily related to walking, it also factors in many other aspects of MS, for example, vision, which might not directly affect walking."

This is particularly important because therapies are now available to improve walking. In 2010, the Food and Drug Administration (FDA) approved dalfampridine (Ampyra, Acorda Therapeutics), a medication aimed at doing just that for patients with MS.

The T25FW was used as a primary outcome measure during the trials that led to FDA approval of that drug, Dr. Bever noted.

Dalfampridine is marketed in Europe by Biogen Idec Inc, under the brand name Fampyra.

This study was funded by an Investigator Initiated Trial Grant from Biogen Idec. Additional funding was provided by the ziMS Foundation. Dr. Goldman has received consultancy funds from Acorda Biogen Idec and Novartis Pharmaceuticals and is grant supported by the National Institutes of Health.

Neurology. Published online October 30, 2013. Abstract

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