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Clinimetric Properties of Timed Walking Events Among Patient Populations Commonly Encountered in Orthotic and Prosthetic Rehabilitation

Stevens, Phillip M. MEd, CPO, FAAOP

JPO Journal of Prosthetics and Orthotics: January 2010 - Volume 22 - Issue 1 - p 62-74
doi: 10.1097/JPO.0b013e3181c63d04
Article
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Outcomes assessment is becoming increasingly prevalent in healthcare. Many assessment measures involve timed ambulatory events and have been validated among those patient populations most commonly encountered in orthotic and prosthetic rehabilitation. These assessments are described, and the ranges of probable performance values across several patient populations are presented. The populations of cerebral vascular accident, cerebral palsy, multiple sclerosis, lower extremity amputation, traumatic brain injury, spinal cord injury, post polio and peripheral neuropathy are then treated individually, with summaries of current reliability findings and other considerations.

Many outcomes assessment measures involve timed ambulatory events and have been validated among those patient populations most commonly encountered in orthotic and prosthetic rehabilitation. These assessments are described, and the ranges of probable performance values across several patient populations are presented. These patient populations are then treated individually, with summaries of current reliability findings and other considerations.

PHILLIP M. STEVENS, CPO, MEd, is affiliated with the Hanger Prosthetics and Orthotics, Salt Lake City, Utah.

Disclosure: The authors declare no conflict of interest.

Correspondence to: Phillip M. Stevens, CPO, MEd, Hanger Prosthetics and Orthotics, 5292 S. College Dr., 103, Salt Lake City, UT 84123; e-mail: philmstevens@hotmail.com

As outcomes assessment becomes increasingly fundamental in the provision of healthcare, it will become progressively more relevant for orthotists and prosthetists to develop a working knowledge of the established outcome measures that have been validated within the published literature, the populations in which the reliability of these measures have been verified and the performance ranges that might be expected with a given measure within a given population. The outcome measures presented in this article are limited to those which involve a timed ambulatory performance, and include the 10-m walk test (10MWT), the 5-m walk test (5MWT), the 25-ft walk test (25FWT), the 6-minute walk test (6mWT), the 2-minute walk test (2mWT), the 1-minute walk test (1mWT), the timed up and go (TUG), the L test of functional mobility (L test) and the timed up and down stairs test (TUDS). In addition to describing each measure, test-retest reliability and descriptive data will be presented for those patient populations most frequently encountered within orthotic and prosthetic rehabilitation, including cerebral vascular accident (CVA), cerebral palsy (CP), multiple sclerosis (MS), lower extremity amputation (LEA), traumatic brain injury (TBI), spinal cord injury (SCI), post polio (PP) and peripheral neuropathy (PN). To maintain relevance and currency, this review includes only data that have been published within the last 10 years.

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METHODS

A search of the literature was conducted in the spring of 2009 using PubMed. The following search terms: “meter walk test,” “minute walk test,” and “TUG” were combined with the terms “CVA,” “CP,” “MS,” “amputation,” “TBI,” “SCI,” and “PP.” The articles reporting on population specific reliability and/or descriptive data for the identified outcome measures were selected. In addition, references in these original articles, which met the same criteria, were examined to reduce the likelihood of relevant literature being overlooked. References were included in the review if they were published between 1999 and the spring of 2009. Publications focusing on treatment interventions, such as physical therapy modalities and pharmaceutical interventions, were not included. However, those publications were included which used one or more of the selected outcome measures to report on an orthotic or prosthetic intervention. Relevant historic literature was included as appropriate to establish historical foundations.

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TIMED WALKING EVENTS

10MWT and 5MWT

One of the most fundamental outcome measures observed in the current literature is that of gait velocity over a short distance. Such assessments have been made over a myriad of defined distances, with 10 m being the most commonly used, and a smaller CVA investigation subset of interest in a 5-m distance. Authors have historically reported this value either as the time taken to complete the designated distance or the calculated walking velocity. Importantly, the length of the walking assessment seems to be significant as authors have reported different walking velocities for the same study cohorts when measured over similar but different distances, both at “comfortable” and “fast” paces (reference).

To the extent that the 10MWT has been standardized, it is a self-paced event in which steady-state walking is timed through the middle 10 m of a 14-m corridor. The initiation of walking and its subsequent deceleration are not captured in the timed event. Ideally, the observer should walk behind the subject during the walking event to avoid pacing the subject at a velocity other than his self-selected speed. There have been several variations on this protocol. For example, the 10MWT has also been conducted with patients instructed to walk as fast as possible and with a still start, where the initiation of gait occurs within the timed 10 m. Shorter times or larger velocities indicate higher performance values. Reliability and descriptive data for several patient populations are listed in Table 1. Reported means were converted variously from times to speeds and vice versa to allow for easier comparisons between the various data sets. However, standard deviations and ranges were not converted. Where means for multiple trials were reported, those from the latest trials are listed in the table.

Table 1

Table 1

Because of the large number of studies reporting on this outcome measure within the CVA population and because of the wide variety of mean times and ranges observed in the various study cohorts, descriptive data for this patient population are not included in Table 1 but will be discussed in the CVA summary section.

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25FWT

The 25FWT is similar to the 10MWT as a measurement in seconds over an established length. This index is performed from a still start and timed from the “go” command through the completion of the clearly marked 25-ft distance. Subjects are instructed to “walk 25 ft as quickly as possible but safely. Do not slow down until after you've passed the finish line.” The published protocols require that on completion of the first timing, the task be immediately administered a second time with the patient returning over the original distance. Assistive devices are used as required. The 25MWT comprises part of the MS functional composite (MSFC), which is broadly accepted as the standard functional assessment measure within that population.1,2 Shorter time values indicate improved performances. Despite a large number of studies reporting on the various psychometric properties of the aggregate MSFC and individual 25FWT, descriptive data for this measure have been reported infrequently. The psychometric properties of the index will be discussed in the MS summary section.

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6mWT

In contrast to the observed gait speeds over short distances, such as the 10MWT and 25FWT, the 6mWT was developed as a means of evaluating exercise capacity. The longer distances require increased endurance and may be more valuable in discerning performance differences among patients who can compensate for certain gait deficits over shorter distances. Formal guidelines for the 6mWT have been established by the American Thoracic Society.3 In practice, subjects ambulate at their selected walking speed for 6 minutes around a track or along a corridor of known distance with the instruction to “walk as far as possible.” The layout of the walking course affects performance values. Shorter courses, which require regular turns as patients walk up and down a corridor, tend to reduce 6mWT values, whereas continuous oval courses increase them.3 Verbal encouragement, when given, should be standardized. Observers record the distance covered during this 6-minute period. Larger distance values indicate better performance. The reliability and descriptive data for several patient populations are listed in Table 2.

Table 2

Table 2

As with the 10MWT, because of the large number of studies reporting on this outcome measure within the CVA population and because of the wide variety of mean times and ranges observed in the various study groups, descriptive data on this patient population were not included in Table 3 but will be discussed in the CVA summary section.

Table 3

Table 3

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2mWT

The 2mWT is simply an abbreviated form of the 6mWT. Within published literature, its use relative to lower-limb prosthetics and orthotics has been largely confined to those with lower-limb amputation. As with the 6mWT, larger distance values indicate better performance. Descriptive data for this index are listed in Table 4, and its clinimetric properties are discussed in the LEA summary section.

Table 4

Table 4

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1mWT

The 1mWT test was specifically designed as a means of assessing exercise capacity among those children who are too disabled to perform more accepted outcome indexes such as the 6mWT and O2 consumption indexes. The protocols for this index have the child walk as fast as possible without running for 1 minute and report the distance covered during that time. Larger distance values indicate better performances. The reliability and descriptive data for the CP population are listed in Table 5.

Table 5

Table 5

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TUG

With the exception of those research designs, which incorporated turns within a corridor for the purposes of a 6mWT, the measures reviewed to this point have only addressed walking. The TUG represents one of the earliest timed walking events to incorporate transfers and turns4,5 and has been variously described as a measure of functional mobility, balance, and postural stability. With this instrument, a subject begins seated in a backed chair with arm rests. Timing begins when the administrator says “go.” The subject rises from his chair, ambulates 3 m at as self-selected speed to a marked line, turns around, returns to his chair, and resumes his seat. Timing stops when the subject's back resumes contact with the back of the chair. Shorter time durations indicate better performance values. The reliability and descriptive data for several patient populations are listed in Table 6.

Table 6

Table 6

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L Test

Citing what they observed as a ceiling affect for the TUG among both younger and more fit elderly amputees, Deathe and Miller6 developed a second timed ambulatory test that retained the transfer skill set of the TUG, but it was more demanding and less prone to ceiling effect. The result was the L test in which patient are timed as they stand from a seated position, typically in an examination room, ambulate 3 m ahead, typically into a clinic hallway, turn 90°, ambulate an additional 7 m down the hallway, turn 180 degrees, return the 7 m to the examination room, turn 90°, and return the 3 m back into the original examination room, where they retake their seat. The resulting measure requires ambulation more than 20 m and turns to both the right and left compared with the 6 m and single turn associated with the TUG. The reliability and descriptive data for the L test are limited to the LEA population and are listed in Table 7.

Table 7

Table 7

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TUDS

Within orthotic and prosthetic practice, use of the TUDS has been limited to the CP population. As originally defined, the TUDS protocol is as follows: subjects are asked to stand 30 cm from the bottom of a 14-step flight of stairs. Subjects are instructed to quickly but safely go up the stairs, turn around on the top step (landing), and come all the way down until both feet land on the bottom step (landing). Subjects are permitted to use whatever stair strategy they choose, including step-to or reciprocating strategies or skipping steps when able. Hand rails can be available. Timing occurs from the assessor's “go” cue until the trailing foot reaches the bottom landing.7 The reliability and descriptive data for the CP population are listed in Table 7.

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PATIENT POPULATIONS

Cerebral Vascular Accident

Among patients with CVA, high reliability has been reported for the 10MWT (intraclass correlation coefficient [ICC] = 0.85–0.98),8–10 5MWT (ICC = 0.80–0.97),11 6mWT (0.91–0.99),10,12–15 and TUG (0.96–0.97).10,13

With respect to the 10MWT, descriptive data for this test were found in six different publications. These include the standardized 10MWT,10,16–19 and modified versions in which subjects used a still start8,9 and/or were instructed to walk as fast as possible.8,10,17,18 Among patients who are at least 6 months past their original CVA, high test-retest reliability has been verified at intervals of 1 minute,8 1 week,9,10 and 1 year.8 However, citing systematic improvements in performances on sequential walks within individual evaluation sessions, authors have encouraged a practice trial at each assessment interval to improve reliability.9 Mean reported values varied greatly according to the various inclusion criteria of the different articles and the versions of the 10MWT used. Overall, mean 10MWT times ranged from 9.5 to 16.9 seconds among CVA cohorts during the first few months poststroke17,18 and from 7.1 to 24 seconds among those cohorts in which subjects were at least 6 months post-CVA.8–10,16,19

With respect to the 5MWT, descriptive data for this test were found in three different publications, all of which studied patients in the first few months post-CVA during the subacute period.11,17,20 These include the standardized 5MWT11,17 and a modified version in which subjects were instructed to walk as fast as possible.17,20 Mean reported velocities were quite variable among the various cohorts and ranged from 0.26 to 1.16 m/s.11,17,20

Even when articles were limited to the past 10 years and comparative intervention trials were eliminated from consideration, multiple descriptive data sets for the 6mWT were identified. These included those performed during both the acute14,18,21 and chronic10,12,13,15,16,19,22–24 phases of recovery. Given the variety in inclusion criterion within the many different investigations, the considerable variability in mean performance times is to be expected. Overall, the mean performance values ranged from 69 to 216 m for those subjects in the subacute phase of rehabilitation and from 197 to 398 m for those in the chronic rehabilitative phase.

Besides the reliability data cited earlier for both acute14 and chronic10,12,13,15 CVA, it should be noted that the test-retest reliability for this index among patients during the subacute phase of rehabilitation is comparatively low (ICC = 0.74–0.78) when considered during a 4-week interval. This is due to a 2.4-fold increase in the index over that time period, suggesting a degree of natural recovery during the first few months poststroke.25 For those patients past the subacute stage of recovery, a practice test does not seem to be necessary.15

The 6mWT has been used to quantify improvements associated with the use of functional electrical stimulation (FES) (NESS L300) among a cohort of subjects with hemiparesis. The mean baseline value of 190.8 m improved to 223.3 m at the initial application of the device and further increased to 244.8 and 255.6 m at subjects' 4- and 8-week follow-up evaluations, respectively.26

With respect to the TUG, descriptive data for this test were found for both acute22 and chronic10,13 subjects (Table 5). The index has been used to evaluate the efficacy of an orthotic intervention within this population on at least one occasion in which TUG values were assessed with and without ankle-foot orthoses (AFOs) among a cohort of chronic CVA subjects.27

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Cerebral Palsy

Among patients with CP, the reliability of the 10MWT (ICC = 0.78–0.81),28 6mWT (ICC = 0.91–0.99),28–30 1mWT (0.94),31 TUG (0.98–0.99),32 and TUDS (0.94)7 have been investigated. Given the variability observed in gross motor function among children and adults with the diagnosis of CP, many authors have organized their observations by dividing their study subjects according to the Gross Motor Function Classification System (GMFCS).33 As the name implies, the GMFCS classifies subjects with CP according their gross motor function abilities with the following classifications for ages 6 to 12 years old:

  • GMFCS level I: children walk indoors and outdoors, and climb stairs without limitations.
  • GMFCS level II: children walk indoors and outdoors, and climb stairs holding onto a railing but experience limitations walking on uneven surfaces and inclines, and walking in crowds or confined spaces.
  • GMFCS level III: children walk indoors or outdoors on a level surface with an assistive mobility device.
  • GMFCS level IV: children may maintain levels of function achieved before age of 6 yrs or rely more on wheeled mobility at home, school, and in the community.
  • GMFCS level V: physical impairments restrict voluntary control of movement and the ability to maintain antigravity head and trunk postures.

The sole investigation of the 10MWT within the CP population reports on a modified version of the instrument in which subjects were positioned with their toes immediately behind the start line of the 10-m length and were told to walk their fastest speed without running (Table 1). Timing began from the moment the subjects initiated a step and ended when the lead foot crossed the finish line, with the subjects encouraged to decelerate only after the finish line.28 While the reliability of this instrument across all GMFCS levels was reported at a respectable ICC value of 0.81, the ICC values for individual GMFCS levels were among the lowest observed for all of the timed walking events across all the patient populations included in this review. The published data for the 10MWT in the CP population suggest that it is a comparatively poor choice of measurement to identify performance improvements outside of measurement error and instrument variability.

Descriptive data for the 6mWT within the CP population were found in three separate publications (Table 2).28–30 In contrast to the 10MWT, this index has consistently been found to be quite reliable across a number of subpopulations including children,28 adolescents,30 and adults29 with CP. The 6mWT was found to discriminate among children of different GMFCS levels28 and between those adults who used walking aids for ambulation and those who did not.29

Some modifications have been described. Most notably, Thompson et al. reported that when assessing younger subjects who might fail to understand the concept of walking continuously for 6 minutes, their assessors provided a series of visual goals placed roughly every 20 m. Each time a subject reached a visual goal, the new goal, 20 m ahead, was targeted.28 Data from children and adolescent populations suggest that a practice test is unnecessary in these populations.28,30 In contrast, the data observed in adults with CP suggest that a practice test should be performed.29

As cited earlier, the 1mWT was developed as a means to assess walking endurance in those children with CP whose level of disability precludes participation in more established, but more exacting and complex outcome indexes. It is the only timed walking outcome measure for which data exist for the GMFCS level IV patient. Significant correlations have been reported between the distance covered during the 1mWT and a subject's performance on the gross motor function measure,34 a standardized assessment tool of gross motor function designed specifically for the CP population.35 In addition, significant decreases in the distance walked during the 1mWT have been reported with increasing GMFCS levels (Table 4).35,36 A moderate correlation seems to exist between the distance covered during the 1mWT and net O2 cost values, though the correlation is not sufficiently strong to permit the use of the 1mWT as a proxy value for O2 costs.35 The reliability of the outcome measure has only been investigated on one occasion with a favorable ICC value of 0.94. However, the authors were clear in stating that there was a systematic bias toward increased walking distance on the second attempt during a given testing session and strongly recommended a practice trial before the administration of the test itself to improve reliability.36

Descriptive data on TUG performance were found in three separate publications (Table 5).7,32,37 Mean values have been reported by GMFCS level7,32,37 and taxonomic classification.37 Exact protocols differed and were often tailored to the study populations. For example, Zaino et al.,7 whose population ranged in age from 8 to 14 years old with a mean age of 11 and with the majority of subjects classified as GMFCS levels I or II, used a standard protocol with variable seat height to ensure that the subject's hip and knees were flexed at 90° at the initiation of the test. Williams et al., whose population had a mean age of 8 years, 7 months but included children as young as 3 years old, and who had a number of children classified at the more severely disabled GMFCS level III, chose to use a concrete objective over the abstract instructions of the standard TUG. These children were instructed to stand up, walk, touch the star (positioned 3 m from the chair), and sit back down. Also, children were told to start whenever they were ready, and timing began when the subjects left their seat rather than when the assessor said “go”.37 In contrast, Gan et al., whose population was similar to that of Williams et al., used more traditional TUG protocols. In addition, they clearly instructed their subjects to “walk as fast as possible without running,” and the timing started as soon as the assessor said “go,” to include the subjects' reaction time in the event.32

In one investigation, the TUG was found to discriminate between subjects across all ambulatory GMFCS levels.7 Other authors reported a lack of statistical separation between GFMCS levels I and II and observed that, as the difference between the two levels is the ability to run and jump, the TUG, as a measure of basic mobility skills, should not be expected to delineate a difference.32,37 Reported TUG times have also reflected the various taxonomic impairment levels.37

Descriptive data on the TUDS within the CP population are limited to a single study in which times were reported by both GMFCS level and ages (Table 7).7

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Multiple Sclerosis

Among this population, the reliability of the 10MWT (ICC = 0.91–0.95),38,39 25FWT (0.98),40,41 6mWT (ICC = 0.95–0.96),38,42 and TUG (ICC = 0.91)39 have been formally evaluated and confirmed.

The diverse and fluctuating nature of MS symptoms makes clinical outcomes assessment in this population very challenging.41 In the presence of these ranges of disability, many authors have categorized and reported on their MS subjects according to the Expanded Disability Status Scale (EDSS).43 The EDSS is a nonordinal scale that ranges from 0.0 or “normal neurological examination” to 10.0 or “death due to MS.” Subjects with EDSS scores between 0 and 3.5 are by definition, “fully ambulatory,” while those with EDSS scores in excess of 6.5 are essentially nonambulant. With respect to ambulatory ability, the intermediate EDSS scores are defined as follows:

  • 4.0: fully ambulatory without aid, able to walk without aid or rest some 500 m.
  • 4.5: fully ambulatory without aid, able to walk without aid or rest some 300 m.
  • 5.0: ambulatory without aid or rest for about 200 m.
  • 5.5: ambulatory without aide or rest for about 100 m.
  • 6.0: intermittent or unilateral constant assistance (cane, crutch, and brace) required to walk about 100 m with or without resting.
  • 6.5: constant bilateral assistance (canes, crutches, and brace) required to walk about 20 m without resting.

Descriptive data on the 10MWT among patients with MS can be found in three separate investigations within the past 10 years (Table 1).38,39,44 Test-retest reliability has been found to be quite high with the use of the standard 10MWT,38 a 10MWT performed as fast as possible,38 and a 10MWT performed at self-selected speeds with a still start.39 Comparisons between studies are challenged by the different protocols used in conducting the 10MWT and the variability in both the severity and types of MS present within the study subjects. However, group 10MWT performance means seemed to be affected by the combination of EDSS distributions and MS types, with lower EDSS values and larger percentages of patients with relapsing remitting MS correlating to improved 10MWT performance values.38

As indicated earlier, the 25FWT is one of three indexes that compose the MSFC. In tabulating MFCS scores, values of the three indexes are individually converted to Z scores against some reference population and then averaged together to create a composite score. This may partially explain the dearth of 25MWT descriptive data in the published literature. With respect to psychometric properties, it has generally been accepted that a change in the 25FWT of greater than 20% usually signifies a clinically relevant change.45–47 Further, there seems to be no discernible practice effect for the index.40,48

The profound diversity of functional abilities within the MS population is suggested in the 25FWT scores cited in the work of Fisk et al. Reporting on a large cohort of 187 subjects across all levels of EDSS disability classification and MS subtypes, the authors reported a mean ± standard deviation for the index of 65 ± 81 seconds with times ranging from 3 to 180 seconds.49

The index has been used to evaluate the efficacy of an orthotic intervention within this population on two occasions. Sheffler et al. reported on the functional effect of AFOs in a pilot study involving 15 comparatively high-functioning subjects with MS who, with minimal or no assistance, had demonstrated sufficient endurance and motor ability to ambulate a minimum of 30 ft continuously without their AFOs. When the subject with the worst 25FWT time, who also benefited the most from the AFO intervention, was removed from statistical consideration, the authors reported mean 25FWT times of 9.3 ± 5.1 seconds and 9.3 ± 5.0 seconds, respectively, for the “no device” versus AFO condition.50 This suggests that the 25FWT is a poor choice of outcome measure to quantify gait improvements in those MS patients who have demonstrated the ability to compensate for their gait deficits without their AFOs over short distances. In a separate investigation, Sutliff et al. reported on a cohort of 21 MS patients with compromised hip flexor strength treated with a hip flexion assist orthosis (HFAO). The baseline 25FWT for this cohort was 18.9 ± 19.1 seconds and was found to be reduced by 5.1 ± 9.7 seconds 8 weeks after the application of the orthosis.51

Descriptive data on the 6mWT within the MS population were found in four separate publications (Table 2).38,42,52,53 Test-retest reliability and interrater reliability have both been assured with reports of ICC values ranging from 0.91 to 0.96 with both the standard 6mWT,38 and a modified 6mWT in which patients were instructed to “walk as far and as fast as possible.”42 Several authors have reported that 6mWT performance values are inversely related to a patient's EDSS level.42,52,53 Further, there does not seem to be a need for a practice test.42 The 6mWT has also been found to be less prone to the floor effects observed when using the 25FWT among patients with mild MS disability.42 The index has been used to evaluate the efficacy of an orthotic intervention within this population on one occasion. Sutliff et al. reported on a cohort of 21 MS patients with compromised hip flexor strength treated with an HFAO. The baseline 6mWT for this cohort was 647.7 ± 423.6 m and was found to increase by 159.2 ± 119.5 m 8 weeks after the application of the orthosis.51

Descriptive data on the TUG within the MS patient population are limited to a single investigation in which the standard TUG was modified with the additional instruction to patients that they walk quickly but safely while performing the measure (Table 5).39 The index has also been used to evaluate the efficacy of the HFAO in the work of Sutlif et al. cited earlier. The baseline TUG for this cohort was 24.5 ± 19.4 seconds and was found to decrease by 6.4 ± 12.3 seconds 8 weeks after the application of the orthosis.51

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Lower-Limb Amputation

Among patients with lower-limb amputation, the reliability of the 6mWT (ICC = 0.94),54 2mWT (ICC = 0.90–0.96),55 TUG (ICC = 0.93),56 and L test (ICC = 0.97)6 have been investigated. As with other populations encountered in orthotics and prosthetics, the levels of disability associated with lower-limb amputation are quite variable according to such factors as subject age, amputation level, cause of amputation, and prosthetics experience. While several authors divided their descriptive data according to some of these subpopulations, they were otherwise quite diverse.

With respect to the 10MWT, the only descriptive data found within the past 10 years reported on a retrospective case study in which authors compared physical performance values of two groups of young men who sustained severe unilateral lower-leg trauma. One cohort comprised subjects who underwent transtibial amputation while the other comprised those who underwent limb salvage procedures (Table 1).57

Descriptive data for the 6mWT within the LEA population are confined to three publications (Table 2).54,57,58 As reported earlier, the test-retest reliability of this index was reported with an ICC value of 0.94, indicating robust reliability. However, the same authors suggested that two practice sessions should be performed to eliminate any practice effect.54

Data sets on the 2mWT in this population are limited to five publications (Table 3).55,59–62 The measure has been found to be responsive to improvements during early rehabilitation efforts postamputation60 and reliable among both inpatient and outpatient lower-limb amputation populations.55 Of note, Brooks et al.60 reported significant differences between men and women in the 2mWT with men performing better, both at initial assessment and over time. The index has been used to substantiate the ultimate attainment of equivalent levels of rehabilitation in patients whose rehabilitation postamputation is interrupted by acute illness or delayed healing of the residual limb.61 It also has been used to suggest that the addition of weight to the transfemoral prostheses of elderly dysvascular subjects does not seem to affect gait speed63 and does not seem to indicate the compromised functional abilities of amputees with bilateral lower-limb amputations at the transfemoral and transtibial level.62

Descriptive data on the TUG in this population were found in four articles (Table 5).56,59,64,65 Dite et al.64 found significant differences in TUG performance between those subjects who had fallen twice or more during the 6-month interval between their postamputation discharge and subsequent follow-up and those who had not. Arwert et al.,66 reporting on unilateral transtibial amputees secondary to peripheral vascular disease, found that at 1 year postamputation, those whose residual tibial length was 12 to 15 cm in length performed significantly better on the TUG than those with residual tibias longer or shorter than that range. The index has also been used to suggest similar patient outcomes after the use of two different types of postoperative rigid dressings in transtibial amputees.65

Reported data on the L test is limited to the work of Deathe and Miller6 (Table 6). Mean and standard deviations have been reported for a number of different subpopulations including amputation level, cause of amputation, age, and reliance on walking aids. In addition, the index was found to be less prone to ceiling effect when compared with the TUG.6

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Traumatic Brain Injury

Excellent reliability has been demonstrated among patients with TBI with both the 10MWT (ICC = 0.95–0.99)67–69 and 6mWT (ICC = 0.94–0.96).68,70 Good reliability has been demonstrated among children with TBI with the TUG (ICC = 0.86).71

With respect to the 10MWT, descriptive data for this index have been reported among four different patient cohorts in three publications (Table 1). Group means and standard deviations have been published for cohorts performing the assessment at both comfortable and fast paces67,68 and with both flying69 and still67,68 starts. The instrument has also been found to be responsive to change, with one author observing improved performances at increasing phases of gait recovery after the initial injury.69

Regarding the 6mWT, descriptive data have been reported among two separate patient cohorts (Table 2).68,69 Regarding the TUG, descriptive data are limited to reports among children with TBI (Table 5).71

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Spinal Cord Injury

As with many of the populations reviewed, the level of disability among persons with SCI is diverse. Factors such as the level of injury, strength, and spasticity coupled with how much proprioception and sensation have been preserved will affect motor function.

Within the outcome measures included in this review, the reliability data for the SCI population are limited to a single publication reporting on the 10MWT (ICC = 0.98),72 6mWT (ICC = 0.98),72 and TUG (ICC = 0.98).72 Descriptive data for the three measures within the SCI population are limited to two publications (Tables 1, 2, and 5).72,73 Two separate publications have suggested that patients with SCI tend to select similar walking velocities for both short- and long-distance timed walking events and that the use of both types of tests within this population to assess a locomotors intervention may be redundant.74,75

The 10MWT has been used to evaluate the efficacy of a FES orthotic approach in patients with incomplete spinal cord injuries. In this investigation, 10MWT assessments were performed with and without the FES intervention at a baseline assessment and 1-year follow-up. The 10MWT walking velocities without the FES unit increased from 0.49 ± 0.53 to 0.74 ± 0.68 m/s, demonstrating a strong therapeutic benefit to the intervention.76

The 6mWT has been used on one occasion to evaluate the efficacy of various orthotic interventions within this population.77 In this endeavor, 6mWT values were collected from a cohort of subjects with SCI presenting across a broad range of disability levels in a series of conditions. These conditions, (with the mean ± standard deviation 6mWT values) included barefoot (138.52 ± 80.49 m), with an articulated AFO (160.87 ± 90.59 m), with a WalkAide FES unit (152.37 ± 78.39 m), and with a combination AFO/FES condition (170.55 ± 76.39 m), suggesting that the AFO/FES combination yielded the best 6mWT outcome.77

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Post Polio

Among patients with PP, reliability data have only been reported on the 6mWT (ICC = 0.90–0.98).78 Descriptive data were identified in two separate publications (Table 2).78,79 Observing significant differences in performance values between the first two iterations of the 6mWT among their cohort, Noonan et al.79 suggested that one practice test should be performed to improve reliability. Gylfadottir et al.78 also reported a tendency toward improved performance with repeated trials, but this trend failed to reach statistical significance.

Descriptive data have also been documented for this population using the TUG, although no reliability investigation was undertaken (Table 5).80

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Peripheral Neuropathy

Among patients with peripheral neuropathy, reliability data have been published for both the TUG (ICC = 0.99)81 and 6mWT (ICC = 0.94).81 However, descriptive data were not reported for either instrument.

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DISCUSSION

The purpose of this review was to enable the orthotics and prosthetics practitioners to better use established timed ambulatory outcome measures. Orthotic and prosthetic services typically are intended to create functional changes in areas such as walking speed, endurance, and balance. In today's healthcare environment, it is increasingly important to be able quantify and relate the amount of change associated with a given intervention. The measures presented in this review were selected on the basis of their established protocols, published descriptive data, and reported test-retest reliability values. This review can thus serve as a resource in selecting an appropriate outcomes assessment tool for a given intervention within a given population. It will help the practitioner to correctly execute the selected outcomes assessment instrument, to appreciate its value against published descriptive values for that index within a given population, and to recognize the degree to which observed changes can be attributed to the intervention itself rather than measurement error or performance variability.

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Keywords:

outcome measures; walk test; timed up and go; cerebral vascular accident; cerebral palsy; multiple sclerosis; lower extremity amputation; traumatic brain injury; spinal cord injury; post-polio

© 2010 American Academy of Orthotists & Prosthetists