Establishing the Reliability of The Step Test Evaluation of Performance on Stairs (STEPS) in Multiple Sclerosis

Abstract

Objective:

To establish the inter- and intra-rater reliability of The Step Test Evaluation of Performance on Stairs (STEPS) for people with multiple sclerosis (PwMS) and examine its relation to clinical mobility measures, cognition, and activity levels.

Design and Setting:

STEPS performance was rated by 3 raters at the initial visit. Two raters observed the STEPS performance via videotape at the initial visit and then 1 week later. Participants also completed in lab clinical mobility tests and cognitive assessments at their initial visit. Activity levels were tracked for the subsequent 6 months.

Participants:

In total, 23 people with relapsing-remitting MS (N=23).

Interventions:

Not applicable.

Main Outcome Measure(s):

Intraclass correlation coefficients (ICCs) were used to assess intra-rater and inter-rater reliability, while correlation analyses compared STEPS performance with cognition, clinical mobility assessments, and activity levels. The inter-rater reliability analysis among the 3 raters included scoring from only the initial evaluation. For the intra-rater reliability, 2 raters viewed and rated the videotaped session for each of the participants and then repeated the same process 1 week later.

Results:

Total STEPS scores demonstrated excellent agreement by ICC for inter- (ICC=0.97) and intra-rater reliability (ICC>0.95) and significant correlations with established clinical mobility assessments in PwMS. Better performance on STEPS was associated with information processing speed and prospective activity levels in PwMS.

Conclusions:

Stair ambulation is a challenging task, integral for mobility and independence, therefore, having a sensitive and valid reliable assessment of stair performance is critical for PwMS. The STEPS assessment is a quick, easily administered, reliable, and valid tool for assessing stair ambulation in PwMS.

Multiple sclerosis (MS) is a progressive neurologic disease characterized by demyelination throughout the central nervous system (CNS), affecting close to 1 million people in the United States.¹ Impaired functional mobility is 1 of the most commonly reported symptoms in people with multiple sclerosis² (PwMS). Impairments in physical function are related to falls in PwMS,³ with 56% of PwMS reporting a fall within 3 months and 37% of PwMS being classified as frequent fallers.⁴ The consequences of the functional impairments and increased fall prevalence in PwMS are severe and have been associated with diminished physical function, activity curtailment, social isolation, and overall diminished quality of life.^5,6

Stair ambulation is a common activity of daily living that may present an added challenge for populations with mobility impairments. Compared with typical overground flat walking, stair navigation presents enhanced task demands, requiring increased interlimb coordination to place the feet on the correct step successfully, larger lower extremity joint moments, joint displacements, and an additional challenge to balance control systems.^7–9 Survey data have also highlighted that stairs present a common hazard associated with falls in all age groups and have been reported to be the leading cause of collisional death among older adults.^10,11 Furthermore, the consequences of stair-related falls are severe, demonstrating an increased risk of mortality and serious injuries such as traumatic brain injury and hip fractures.¹¹ Previous work has shown that PwMS demonstrated increased trunk sway correlated with increased disease severity,¹² and decreased stair ascent and gait performance.^13,14 Further, movement pattern compensations are associated with impaired stair ascent performance.¹⁵ Therefore, considering PwMS presents with functional impairments and increased fall risk,⁴ stair ambulation presents a significantly increased challenge in PwMS.

The clinical evaluation of stair performance in PwMS is critical. Several clinical assessments of gait and balance on flat surfaces have established validity and reliability, such as the timed Up and Go¹⁶ (TUG), the timed 25-foot walk test forward¹⁷ (FW-T25FW), and the 3-meter BW walk test.¹⁸ In contrast, there are few assessments of stair ambulation with established validity and reliability in PwMS. The Step Test Evaluation of Performance on Stairs (STEPS) was recently developed to assess stair performance and safety in neurologic populations.¹⁹ This stair evaluation tool exhibited excellent inter- and intra-rater reliability in a Huntington’s disease population, and better STEPS performance correlated with better motor and mobility scores.¹⁹ However, the reliability and validity of STEPS in PwMS has not yet been established.

Therefore, the purpose of this study was to (1) establish the inter- and intra-rater reliability of the STEPS in PwMS; (2) assess the concurrent validity of STEPS with commonly used functional mobility and cognitive assessments (FW and BW T25FW, FW, and BW velocity, TUG, and the Symbol Digit Modalities Test (SDMT) and Trail Making Test A and B (TMT-A and TMT-B)); and (3) examine the relation of STEPS performance to activity level at 3 and 6 months post study visit. We hypothesized that STEPS would have high reliability among raters. We further expected strong support of construct validity based on correlations with established functional and cognitive assessments and prediction of prospective activity levels. Establishing the reliability and validity of standardized tests to adequately assess functional stair performance in PwMS, such as STEPS, is important for examining treatment effects in clinical and research settings.

Methods

Participants

All study procedures were approved by the Wayne State University Institutional Review Board, and participants signed an informed consent form before participation. Participants were eligible to participate if they were 18 years of age or older, had been diagnosed with relapse-remitting multiple sclerosis (RRMS) using the McDonald criteria,²⁰ reported a Patient Determined Disease Steps (PDDS) score <6,²¹ indicating the ability to ambulate with or without an assistive device >50% of the time. Participants were deemed ineligible if they had an MS relapse/exacerbation within the past 30 days, a comorbid neurologic disorder, another condition that would affect their cognitive or motor function, or if they were unable to follow study-related commands. Participants were compensated via gift cards based upon completion and compliance with study protocols.

Procedures

All visits took place in a single testing session. Participants also completed a series of survey measures via REDCAP, including the PDDS as a measure of disease severity and demographic information such as age, sex, and disease duration. Participants also completed the Modified Fatigue Impact Scale²² and the Standardized Neurology Health-Related Quality of Life-Fatigue subscale.²³

Step Test Evaluation of Performance on Stairs (STEPS)

The STEPS assessment was used to measure stair ambulation and was conducted according to methods established by Kloos et al, 2015.¹⁹ Briefly, the assessment comprises a total of 16 items; each item is given a score of 0–1 or 0–2 with a total score of 20. Eight items evaluate stair ascent performance, and 8 items assess stair descent performance. Higher scores on the STEPS indicate better performance. The assessment was performed in a well-lit stairway, and stair ambulation was evaluated in a flight of 10 standard-height steps with bilateral handrails. A stopwatch was used to measure the duration of the stair ascent and descent. A camera was also used to record the STEPS performance to permit the inter-rater and intra-rater reliability analysis. Participants were able to use assistive devices if necessary. The STEPS assessment took approximately 5 minutes to complete.

Walking assessments

Participants wore a gait belt for all walking trials and were accompanied by a research assistant to ensure participant safety. Participants completed the forward and backward timed 25-foot walk test (FW- and BW-T25FW),^17,24 forward and backward walking assessments over a 16-foot GaitRite walkway,²⁵ and the TUG test.¹⁶ Each of these functional mobility assessments has depicted reliability and validity in an MS-specific population.^16,17,24,25

Cognitive assessments

Participants then completed a series of cognitive assessments, including the symbol digits modalities test²⁶ (SDMT) which was used as an assessment of information processing speed and the trails making test A+B²⁷ (TMT-A, TMT-B) was used to assess attention and cognitive flexibility. All cognitive assessments have documented reliability in evaluating cognitive function in PwMS.^26,27

Activity level

At the end of the testing session, participants were equipped with a FitBit Versa 2 that passively captured physical activity data for the subsequent 6 months using Fitabase (Fitabase, San Diego, CA).

Reliability study design

Inter-rater reliability

Three physical therapists (PTs) completed the assessments (PT1, PT2, PT3) which took place in a single testing session. All raters received training on scoring the STEPS before starting the study. Each of the raters had extensive experience in treating individuals with neurologic disorders. One of the raters (PT1) was the administering rater (AR), who guided and instructed each of the participants. While rater PT1 administered the assessment, raters PT2 and PT3 viewed a videotaped recording of the initial assessment and provided the scoring. The inter-rater reliability analysis among the 3 raters (PT1, PT2, and PT3) included scoring from only the initial evaluation. Repetitive testing on the same day was not feasible due to excessive fatigue, 1 of the most commonly reported symptoms in PwMS,²⁸ while testing subjects on multiple days was not viable owing to symptom variability. However, the study design of testing participants on single days has previously been used in validation studies in populations such as Parkinson’s disease²⁹ and Huntingdon’s disease.¹⁹

Intra-rater reliability

Two of the raters (PT2 and PT3) viewed and rated the videotaped initial test session for each of the participants then repeated the same process 1 week later. Raters viewed each participant’s taped performance only once without slowing or stopping the tape to simulate the observational conditions in the clinic and were not allowed to talk with each other. Viewer ratings of videotaped performances of individuals have been used frequently in reliability studies.^29,30 The 1-week delay was considered sufficient to guard against a rater having an explicit memory of their previous rating.

Statistical analysis

The inter- and the intra-rater reliability of STEPS performance were analyzed using a 2-way random effects intra-class correlation coefficient model of absolute agreement with multiple raters [ICC (2,k); where k=number of raters]. Inter-rater reliability was tested as the average agreement among all raters, as well as the pairwise agreement of each rater pair, in the initial evaluation. The intra-rater reliability reflects how the measurements by raters (PT2 and PT3) differed when watching the videotaped sessions 1 week apart. As the same video recording was used for the test-retest reliability, the ICC(2,1) formula was used to assess absolute agreement of the rater with themselves as a conservative estimate of intra-rater reliability. A coefficient value of >0.85 was considered excellent, between 0.75 and 0.85 was considered good, while a value of <0.75 was considered fair.³¹

After reliability testing, construct validity of STEPS was assessed in relation to established measures of function and activity. Data were inspected for normality using skewness, kurtosis, and Shapiro-Wilks test. Normal distributions are not required for valid ICC estimates³²; however based on the assessment of normality, non-parametric correlations were used for further hypothesis testing. Spearman rho correlations were used to assess the concurrent validity of STEPS with other clinical gait and balance outcomes in PwMS including the FW- and BW-T25FW, FW- and BW-velocity, the TUG, as well as the SDMT and TMT. The average total STEPS score across all 3 raters during the first evaluation was used in the correlation analysis. Spearman correlation values were classified as fair (0.25–0.49), moderate to good (0.50–0.75), and excellent (>0.75). Spearman rho correlation was also conducted to examine the relation of STEPS performance to activity level at 3 and 6 months post-study visit. Statistical significance was set to (α=0.05) for each of the analyses conducted. Two participants had missing STEPS data, therefore, the analysis is reported for the total available sample with a pairwise deletion on variables with missing data (n=21).

Results

Participants

Twenty-three participants with RRMS participated in the study. The cohort of MS participants was composed of 18 women and 5 men, with an average age of 50.91±10.45 years. Disease severity, as measured by the PDDS, ranged from 0 to 6 with a median of 2, while the average disease duration was 15.55±10.49 years. Further demographics and clinical demographics can be found in table 1.

Table 1.

Participant demographics

Measure	Mean ± SD	Min-Max
Age (years)	50.91 (10.45)	25–67
Sex	18F:5M	–
Disease duration (years)	15.55 (10.49)	2–37
PDDS	Median=2.0	0–6
MFIS	26.32 (14.48)	0–52
Neuro-QOL-Fatigue	46.33 (7.03)	34.5–62.7
Walking Assessments
TUG (s)	13.94 (12.68)	6.25–57.31
FW-T25WT (s)	12.06 (15.12)	4.45–75.62
BW-T25WT (s)	23.56 (30.35)	3.77–129.30
FW-Velocity (m/s)	1.22 (0.47)	0.44–2.83
BW-Velocity (m/s)	0.81 (0.46)	0.07–2.35
Cognitive Assessments
SDMT	45.35 (13.62)	21–70
TMT-A (s)	33.08 (16.01)	15.72–84.6
TMT-B (s)	86.88 (65.73)	24.35–340
Prospective Falls and Activity Level
Falls 3-month (#)	Median=1	0–8
Falls 6-month (#)	Median=1	0–10
Near-Falls 3-month (#)	Median=4	0–40
Near-Falls 6-month (#)	Median=12	0–71
3-month total steps	5388 (2925)	1640–12,574
3-month active minutes	214.32 (73.93)	112.55–390.14
3-month very active minutes	7.07 (9.66)	0.10–38.15
3-month sedentary minutes	908.52 (154.84)	697.93–1213.56
6-month total steps	5357 (2993)	1613.56–11,752.45
6-month active minutes	209.51 (83.22)	87.70–396.14
6-month very active minutes	6.42 (8.14)	0.09–27.69
6-month sedentary minutes	937.12 (179.87)	621.67–1352.80

NOTE. Outcomes are reflective of the total sample size N=23.

Abbreviations: BW-T25WT, backward timed 15-foot walk test; BW Velocity, backward walking velocity; FW-T25WT, forward timed 15-foot walk test; FW Velocity, forward walking velocity; MFIS, Modified Fatigue Impact Scale; Neuro-QOL-fatigue, standardized neurology health-related quality of life-fatigue subscale; TMT, Trails Making Test.

Inter- and intra-rater reliability of STEPS

The inter-rater reliability score for the total STEPS score was excellent across all 3 raters ICC(2,2)=0.965. Further, similar ICC values were observed for the total STEPS score between all combinations of raters, with all estimates depicting excellent inter-rater reliability ICC(2,2)>0.90 (table 2, fig 1). The intra-rater reliability score for the total STEPS scores recorded by the 2 video review PT raters (PT2 and PT3) on Day 1 and 1 week later was excellent, with estimates ICC (2,1)>0.95 for each rater (table 2, fig 2).

Table 2.

Inter-rater and intra-rater reliability of total STEPS scores

Rater Combination	N	ICC (95% CI)
Inter-rater Reliability
All raters (PT1, PT2, PT3)	21	0.965 (0.927–0.984)
PT1/PT2	21	0.915 (0.789–0.965)
PT1/PT3	21	0.948 (0.871–0.979)
PT2/PT3	21	0.978 (0.946–0.991)
Intra-rater Reliability
PT2	21	0.962 (0.909–0.84)
PT3	21	0.982 (0.957–0.993)

NOTE. Intraclass class correlation values and 95% confidence intervals for inter-rater and intra-rater reliability. In the available sample of 23 participants, 2 individuals had incomplete STEPS assessment data so they were excluded.

Fig 1.

Inter-rater reliability of total STEPS across the combination of the three raters. In the available sample of 23 participants, 2 individuals had incomplete STEPS assessment data so they were excluded. (A) Physical Therapist 1 versus Physical Therapist 2, (B) Physical Therapist 1 versus Physical Therapist 3, (C) Physical Therapist 2 versus Physical Therapist 3. Total STEPS scores are reflective of each rater’s initial evaluation.

Fig 2.

Intra-rater reliability of total STEPS score between raters 2 and 3 (rater 2 in green, rater 3 in blue). In the available sample of 23 participants, 2 individuals had incomplete STEPS assessment data so they were excluded. The x-axis reflects the total STEPS score of Physical Therapist raters at initial evaluation and the y-axis reflects the total STEPS score of the Physical Therapist raters one week later. Rating scores at each time point were made by watching a recorded videotape of each performance. The x- and y-axis were set to be equivalent and a reference line was fit to the diagonal.

Concurrent validity of STEPS in PwMS

Spearman rho correlations revealed significant, moderate to good relations between total STEPS score and the various walking assessment measures (all correlations >0.50). Regarding cognitive outcomes, the total STEPS score demonstrated a significant positive correlation with the SDMT (ρ=0.54, P=.01, however, no significant association was observed with TMT-A (ρ=−0.40, P=.08) or TMT-B (ρ=−0.29 P=.20). Correlations between total STEPS score and mobility and cognitive measures can be observed in table 3.

Table 3.

Correlations between total STEPS score and mobility and cognitive measures

Measure	Correlation (95% Confidence Interval)	P Value
Participant Characteristics
Age	−0.489 (−0.693, .071)	.02
Symptom duration	−0.427 (−0.770, −0.070)	.06
PDDS	−0.626 (−0.828, −0.252)	.002
MFIS	0.242 (−0.256, 0.580)	.29
Neuro-QOL-Fatigus	0.170 (−0.230, 0.598)	.46
Walking Assessments
BW Velocity	0.635 (0.267, 0.841)	.002
FW Velocity	0.587 (0.196, 0.817)	.005
BW-T25W	−0.627 (−0.837, −0.255)	.002
FW-T25W	−0.597 (−0.822, −0.210)	.004
TUG	−0.580 (−0.814, −0.185)	.006
Cognitive Assessments
SDMT	0.535 (0.121, 0.791)	.01
TMT-A	−0.402 (−0.724, 0.063)	.08
TMT-B	−0.292 (−0.651, 0.173)	.2

NOTE. Spearman rho correlations and 95% confidence intervals for total STEPS score and participant demographics, walking assessments, and cognitive assessments. In the available sample of 23 participants, 2 individuals had incomplete STEPS assessment data so they were excluded. Significant correlations are highlighted in bold.

Abbreviations: BW-T25WT, backward timed 15-foot walk test; BW Velocity, backward walking velocity; FW-T25WT, forward timed 15-foot walk test; FW Velocity, forward walking velocity; MFIS, Modified Fatigue Impact Scale; Neuro-QOL-fatigue, standardized neurology health-related quality of life-fatigue subscale.

STEPS performance and prospective activity level at 3 and 6 months

As an assessment of predictive validity, total STEPS score was significantly, positively correlated with very active minutes at both 3 months (ρ=0.57, P=.007) and at 6 months (ρ=0.46, P=.03). Total STEPS score also had a modest positive correlation with total number of steps at 3 month (ρ=0.43, P=.05) and 6 months (ρ=0.42, P=.06), however the associations did not reach statistical significance. All other correlations between total STEPS score and activity level were not statistically significant (table 4). The overall wear-time compliance for the FitBit device for the 6-month physical activity tracking was 91%.

Table 4.

Correlation of total STEPS score with activity level at 3 and 6 months

Measure	Correlation (95% Confidence Interval)	P Value
3 Months
Sedentary minutes	0.16 (−0.244. 0.588)	.49
Lightly active minutes	0.26 (−0.216, 0.607)	.26
Fairly active minutes	0.38 (−0.187, 0.626)	.09
Very active minutes	0.57 (−0.054, 0.701)	.007
Total active minutes	0.30 (−0.152, 0.648)	.19
Total steps	0.43 (0.055, 0.753)	.05
6 Months
Sedentary minutes	0.30 (−0.175, 0.633)	.19
Lightly active minutes	0.11 (−0.347, 0.510)	.62
Fairly active minutes	0.39 (−0.115, 0.669)	.08
Very active minutes	0.46 (−0.138, 0.655)	.03
Total active minutes	0.20 (−0.298, 0.549)	.38
Total steps	0.42 (−0.036, 0.711)	.06

NOTE. Spearman rho correlations and 95% confidence intervals of total STEPS score with activity levels at 3 and 6 months. In the available sample of 23 participants, 2 individuals had incomplete STEPS assessment data so they were excluded. Significant relations are highlighted in bold.

Discussion

This study evaluated the reliability and validity of the STEPS assessment in PwMS. Our study reports 3 main findings: (1) the STEPS assessment showed excellent inter- and intra-rater reliability; (2) evidence of concurrent validity with significant correlations to established clinical mobility assessments in PwMS, and notably a significant correlation with information processing speed; and (3) STEPS performance was associated with prospective activity levels in PwMS. Our study contributes to the existing literature on stair navigation performance in PwMS.^13,15 However, it offers a novel contribution by establishing the reliability and validity of the STEPS assessment as a clinical tool for evaluating stair performance in PwMS.

Our study demonstrates excellent inter- and intra-rater reliability for the STEPS assessment (table 2). This extends prior research, which has already demonstrated the reliability of STEPS for assessing stair performance in other clinical populations like Huntington’s disease.¹⁹ PwMS often face mobility and balance issues,² muscle weakness,³³ and fatigue,²⁸ all of which can affect their ability to navigate stairs. Although that prior work had provided promising support of STEPS, reliability is a property of the sample and therefore cannot be assumed to generalize across clinical populations or study settings. Previous research has highlighted that PwMS may use compensatory movements when climbing stairs.¹⁵ Because stair climbing is a common daily activity, any decline in performance can threaten independence and quality of life in PwMS. Therefore, establishing the reliability and measurement properties of STEPS as a clinical assessment tool for stair performance in PwMS is not only important but also warranted. STEPS has the added advantage of being a quick assessment that requires minimal equipment, making it a practical and clinically significant tool for evaluating functional mobility in PwMS.

Performance on STEPS significantly correlated with other reliable and commonly used clinical assessments of functional mobility in PwMS, providing strong support for construct validity. For instance, high STEPS performance was associated with high performance on walking assessments like FW and BW T25FW, TUG, and increased FW and BW velocity (table 3). These findings affirm the concurrent construct validity of the STEPS assessment, indicating its measurement of postural control and mobility in PwMS.

Our findings align with previous research linking stair performance to functional mobility assessments.^14,19 The strongest correlations observed with STEPS were with both BW-T25FW and BW velocity. BW is a challenging and complex motor task, and previous research has shown that BW velocity is a more sensitive indicator of fall risk in PwMS than FW.³⁴ This finding supports the notion that stair climbing can be equally challenging for PwMS, suggesting its potential as a fall risk screening tool in future studies. Notably, STEPS performance also correlated significantly with PDDS, with poorer performance linked to higher disease severity levels. Our MS participants exhibited a range of PDDS scores, from 0 to 6, underscoring the reliability of the STEPS assessment in evaluating stair performance across a comprehensive range of disability levels. Ultimately increasing the translation of study outcomes reflective of the distinct heterogeneity of MS.

As an additional assessment of predictive validity, we tested the association of STEPS performance and prospective activity levels in PwMS. High STEPS performance correlated with more very active minutes at 3 and 6 months post-study (table 4). Although not statistically significant, we observed moderate correlations between STEPS and total step counts at both 3 and 6 months (table 4). This evidence of sensitivity for prediction of future activity levels up to 6 months later makes STEPS a particularly useful assessment for longitudinal observational and clinical trials, with strong clinical translation to everyday function.

As previously emphasized, stair navigation is a fundamental daily activity important for mobility in our environments and communities, closely tied to independence and community participation.³⁵ Previous studies have highlighted that activities such as stair climbing and backward walking are high-level activities for persons with neurodegenerative disease.³⁶ Our findings corroborate other initial evidence of backward walking associated with prospective very active minutes. Given that PwMS often face mobility and balance issues,³⁷ an increased risk of falls,⁴ and a fear of falling,⁶ it’s plausible that difficulties with stair navigation may lead to reduced activity levels and reluctance to engage with their surroundings, ultimately affecting their overall activity. Considering that falls during stair navigation are common in PwMS, with more severe consequences, avoidance behavior is a plausible response. Our study findings offer valuable insights for future research investigating the relation between stair performance and activity levels in PwMS.

Stair negotiation poses both greater physical and cognitive demands.³⁸ Successful stair navigation requires the ability to integrate and process multiple forms of sensory information during the complex locomotor task.¹¹ PwMS often exhibit notable mobility and cognitive impairments,^2,39 intensifying the challenge of stair navigation. Previous research with older adults has shown that cognitive deficits can affect stair performance.⁴⁰ Specific cognitive domains, including attention,⁴¹ executive function, and processing speed,⁴² have been linked to stair performance. Our study reports that better stair ambulation was associated with enhanced information processing in PwMS. Stair ambulation is a complex task, and previous studies have explored how task complexity relates to specific cognitive domains, such as information processing speed, in PwMS.⁴³ Additionally, prior research has noted correlations between information processing speed and similarly challenging tasks like backward walking.⁴⁴ Our findings offer valuable insights for future research investigating the interplay between cognitive factors and stair navigation in PwMS.

Study limitations

Our study has several important limitations to consider. First, it exclusively focused on RRMS, limiting the generalizability of our findings to other MS subtypes. Further, our study involved a relatively small sample size of 23 PwMS, which was sufficient to provide excellent power and precision of the reliability estimates, but the additional validation analyses would benefit from larger samples with greater diversity. Future work with larger sample sizes pooled across multiple centers would enhance the interpretation of STEPS as a clinical assessment tool of stair performance in PwMS. Furthermore, it’s important to note that the STEPS assessment primarily measures stair functional performance and does not consider stair use history or frequency. While incorporating these factors could provide valuable context, our study primarily aimed to evaluate the measurement properties of STEPS for assessing stair performance in PwMS. Future studies should consider including measures of stair history and confidence alongside the functional STEPS assessment to enhance outcome interpretation.

Conclusions

The STEPS assessment demonstrated excellent reliability and strong support for validity to evaluate stair performance in PwMS. Furthermore, better STEPS performance was associated with improved information processing speed and future activity levels in PwMS. Stair ambulation is a challenging task, integral for mobility and independence, therefore having a sensitive and valid reliable assessment of stair performance is critical for PwMS. In summary, the STEPS assessment is a quick, easy-to-administer, reliable, and valid tool for assessing stair ambulation in PwMS.

List of abbreviations:

BW

backward

CNS

central nervous system

FW

forward

HD

Huntingdon’s disease

ICC

intraclass correlation coefficient

MFIS

Modified Fatigue Impact Scale

Neuro-QOL-fatigue

standardized neurology health-related quality of life-fatigue subscale

PDDS

Patient Determined Disease Steps

PT

physical therapist

PwMS

people with multiple sclerosis

RRMS

relapse-remitting multiple sclerosis

SDMT

symbol digits modalities test

STEPS

The Step Test Evaluation of Performance on Stairs

TMT-A

trails making test A

TMT-B

trails making test B

TUG

timed Up and Go

T25FW

timed 25-foot walk