Minimally important clinical difference of the Timed 25-Foot Walk Test: results from a randomized controlled trial in patients with multiple sclerosis

A pooled analysis of two phase 3 clinical trials of dalfampridine in patients with multiple sclerosis

BACKGROUND

Two phase 3 clinical trials demonstrated that dalfampridine extended-release 10-mg tablets (D-ER), twice daily, significantly improved walking relative to placebo in patients with multiple sclerosis (MS). The objective of this study was to evaluate the efficacy and safety of D-ER in patients with MS using pooled data from the two phase 3 trials.

METHODS

Data were pooled from the two trials, and D-ER was compared with placebo for timed-walk responder rate, changes in walking speed, and the 12-item Multiple Sclerosis Walking Scale (MSWS-12). Response rates were evaluated with respect to demographic and clinical characteristics.

RESULTS

D-ER had a significantly higher proportion of timed-walk responders relative to placebo (37.6% vs. 8.9%; P < .0001). The responder rate was independent of age, gender, race, body-mass index, type of MS, duration of MS, baseline Expanded Disability Status Scale score, baseline walking speed, and concomitant use of immunomodulatory therapies. Significant improvements were observed in walking speed and in MSWS-12 score for the pooled D-ER group compared with placebo. The safety profile was consistent with the individual studies; no new safety or tolerability concerns were identified.

CONCLUSIONS

D-ER demonstrated efficacy for the improvement of walking in patients with MS; response was independent of demographic and clinical characteristics.

Effect of a 2-week trial of functional electrical stimulation on gait function and quality of life in people with multiple sclerosis

BACKGROUND

Footdrop is a common gait deviation in people with multiple sclerosis (MS) leading to impaired gait and balance as well as decreased functional mobility. Functional electrical stimulation (FES) provides an alternative to the current standard of care for footdrop, an ankle-foot orthosis (AFO). FES stimulates the peroneal nerve and activates the dorsiflexor muscles, producing an active toe clearance and a more normal gait. This study was undertaken to determine the effects of a 2-week FES Home Assessment Program on gait speed, perceived walking ability, and quality of life (QOL) among people with MS-related footdrop.

METHODS

Participants completed the Timed 25-Foot Walk test (T25FW) and two self-report measures: 12-item Multiple Sclerosis Walking Scale (MSWS-12) and 29-item Multiple Sclerosis Impact Scale (MSIS-29). Measures were taken without FES before and with FES after 2 weeks of full-time FES wear.

RESULTS

A total of 19 participants (10 female, 9 male) completed the study; mean age and duration of disease were 51.77 ± 10.16 and 9.01 ± 7.90 years, respectively. Use of FES for 2 weeks resulted in a significant decrease in time to complete the T25FW (P < .0001), the MSWS-12 standardized score (P < .0001), and the MSIS-29 total (P < .0001), Physical subscale (P < .0001), and Psychological subscale (P = .0006) scores.

CONCLUSIONS

These results suggest that use of FES can significantly improve gait speed, decrease the impact of MS on walking ability, and improve QOL in people with MS-related footdrop even over a short period of time.

Addressing the regulatory and scientific challenges in multiple sclerosis – a statement from the EU regulators

Improving and facilitating the process of making new drugs available to patients with multiple sclerosis (MS) requires cooperation among the regulators and other stakeholders. This cooperation will also positively contribute towards developing guidelines of the highest quality in medical, regulatory and scientific aspects. This would be beneficial both in areas that require further guideline development, but also in fields where existing guidance should be adapted to take into account evolution in science. Considering the input from all stakeholders, the European Medicines Agency confirmed its intention to update the relevant guideline and apply a flexible approach towards new drug development strategies in MS. This article is the first official position from the EU regulators, presenting the main changes to be expected in the guidance document.

Factors associated with clinically significant increased walking time in multiple sclerosis: results of a survival analysis of short-term follow-up data from a clinical database

BACKGROUND

Because multiple sclerosis (MS) is variable and unpredictable, if symptom worsening could be predicted, patients may feel better prepared to manage changes in function.

OBJECTIVE

The objective of this paper is to study the prediction of walking impairment in MS.

METHODS

We retrieved data for all MS patients at our center (2008-2009), including baseline and follow-up timed 25-foot walk (T25FW) times. We assessed the incidence of ≥20% worsening in T25FW by developing two survival models: (1) disease course and (2) Multiple Sclerosis Performance Scales (MSPS) score. The outcome was days until ≥20% worsening in T25FW. Covariates were disease subtype, years since diagnosis, Patient Health Questionnaire-9 (PHQ-9) score, and demographics. Data were interval censored; missing data were handled with multiple imputation.

RESULTS

Of 1544 patients, 309 (20%) experienced ≥20% worsening T25FW. For disease course, time to worsening was significantly shorter for secondary progressive vs. relapsing-remitting disease (p < 0.001). For MSPS, patients with lower baseline MSPS scores progressed more slowly (p = 0.001). In both models, sex, baseline T25W, and time since diagnosis were significantly associated with worsening. In the disease course model, PHQ 9 score may be related to worsening (p = 0.07).

CONCLUSION

These findings suggest factors associated with worsening in T25FW and a potential approach to establishing indicators associated with clinically significant change.

A 3meter Timed Tandem Walk is an early marker of motor and cerebellar impairment in fully ambulatory MS patients

BACKGROUND

Mobility assessment in Multiple Sclerosis (MS) is crucial for trials and individual patient counseling. Up to now, standard tests as the Timed 25-Foot Walk (T25FW) are restricted by floor effects in mildly disabled patients. The 3-meter Timed Tandem Walk (TTW) as a possibly more sensitive measure has not been investigated yet.

OBJECTIVE

To investigate sensitivity and specificity of the TTW and T25FW to detect mild clinical impairment in a large cohort of MS patients.

METHODS

We extracted T25FW, TTW and EDSS from our UMC patient database (2009-2012). After randomization into an explorative (n = 497) and validation (n = 228) cohort, we calculated change rates and performed ROC analyses of gait tests and EDSS including Functional System Scores.

RESULTS

Between disability stages of EDSS 0-2.5 and EDSS 3.0-4.0, the mean TTW difference was 4s (T25FW = 0.9s). The accuracy to separate between EDSS groups was moderate but identical for both tests (ROC-AUC T25FW = 0.79, TTW = 0.80, p = 0.4). TTW had a higher sensitivity and specificity to differentiate between asymptomatic and symptomatic patients concerning FS motor/cerebellar scores (ROC-AUC T25FW = 0.71, TTW = 0.75, p < 0.05). All hypotheses could be validated in the second cohort.

CONCLUSION

A 3-m Timed Tandem Walk is a standardized test that is easy to implement to detect impairment of the motor or cerebellar system in fully ambulatory MS patients. Based on the complex-task character, TTW is a potential new outcome measure for MS mobility in mildly disabled patients and can act as easily accessible and significant additional information in patient counseling.

Minimal clinically important difference for change in comfortable gait speed of adults with pathology: a systematic review

RATIONALE, AIMS AND OBJECTIVES

Walking speed is an important performance variable, but information on the minimal clinically important difference (MCID) for the measure has not been consolidated. In this review, we aimed to summarize information on the MCID for change in comfortable gait speed measurements for patients with pathology.

METHODS

Relevant literature was identified by searches of four databases (PubMed, Web of Knowledge, CINAHL and Scopus), hand searches and consultation with an expert. Inclusion required that articles reported a MCID for comfortable gait speed measurements. Articles were excluded if the MCID was not determined using receiver operating characteristic (ROC) curve analysis. Articles were abstracted for information on participants, interventions, gait speed documentation and the determination of MCID. Quality was assessed using a hybrid 9-item (0-18 point) instrument.

RESULTS

Seven articles were selected based on inclusion and exclusion criteria. The populations studied included stroke (n = 3), hip fracture (n = 2), multiple sclerosis (n = 1) and mixed (n = 1). Using 13 different anchors the studies reported MCIDs of 0.08-0.26 m s(-1) . All but three of these MCIDs were between 0.10 and 0.20 m s(-1) . All MCIDs for which the area under the ROC curve exceeded 0.70 were between 0.10 and 0.17 m s(-1) .

CONCLUSIONS

Changes in gait speed of 0.10 to 0.20 m s(-1) may be important across multiple patient groups.

Changes in cognition, arm function and lower body function after slow-release Fampridine treatment

OBJECTIVE

We aimed to evaluate the effect of slow-release (SR) Fampridine on multiple outcome measures reflecting different domains, and to compare the responsiveness of the Six Spot Step Test (SSST) and the Timed 25 Foot Walk (T25FW).

METHODS

For this study 108 participants were included. On day 0 they were tested with the T25FW, the SSST, the 9-Hole Peg Test (9-HPT), the 5 Times Sit-To-Stand test (5-STS) and the Symbol Digit Modalities Test (SDMT). Four weeks of treatment with SR Fampridine 10 mg BID was commenced. Participants were tested again after 26-28 days of treatment.

RESULTS

Mean changes observed were: SSST -3.4±6.4 s (p<0.001), T25FW -1.2±3.7 s (p<0.001), 9-HPT -1.2±6.0 s (p<0.001), 5- STS -3.4±7.2 s (p<0.001) and SDMT 1.4±4.8 a.u. (p=0.003). Change on the SSST differed significantly from T25FW (SSST 17.0±19.6% vs. T25FW 11.2±17.1%, p=0.0013). Some 48.6% were found to have a meaningful change on the SSST compared with 25.7% on the T25FW. The response to treatment with SR Fampridine did not correlate with age, sex, Expanded Disability Status Scale and disease duration.

CONCLUSION

SR Fampridine treatment has significant effects on different domains including upper and lower body and cognition. Furthermore, the SSST is more responsive to the effect of SR Fampridine than is the T25FW. ClinicalTrials.gov identifier: NCT01656148.

Sustained-release fampridine (4-aminopyridine) in multiple sclerosis: efficacy and impact on motor function

Objective

The aim of this study was to determine the efficacy of sustained-release fampridine (4-aminopyridine) in veterans with multiple sclerosis (MS) with limited ambulatory ability, and its impact on motor function in an outpatient setting.

Design

Retrospective.

Setting

Tertiary referral center [Veterans Affairs (VA) Medical Center].

Participants

Veterans; 20 MS patients were prescribed dalfampridine (10 mg twice daily) due to their difficulty with walking based on patient and caregiver report and clinician impression of change in the ability to ambulate based on prior 10-meter (10M) and 2-minute walk tests (2MWTs).

Intervention

Not applicable.

Main Outcome Measures

The primary outcome measures were mean changes in walking speed (10M walk test), walking distance (2MWT), and Total Functional Independence Measure (TFIM). Improvement of >20 % in walking speed was indicated as a clinically meaningful change.

Results

Treatment with dalfampridine resulted in significant improvement in walking speed and endurance (p < 0.05). Walking speed increased by 33 % and walking endurance by 31 %, representing clinically meaningful improvement. This change was not influenced by change in muscle tone. This improvement in mobility was associated with a clinically significant change in motor function. Adverse effects, including insomnia, dizziness, and headache, were experienced by five patients who discontinued the medication after a minimum of 4 weeks.

Conclusion

Treatment with dalfampridine resulted in clinically relevant improvements in walking speed and endurance in MS patients with limited ambulation and helped improve their motor function.

Electronic supplementary material

The online version of this article (doi:10.1007/s40268-013-0020-x) contains supplementary material, which is available to authorized users.

4-Aminopyridine for symptomatic treatment of multiple sclerosis: a systematic review

This systematic review summarizes the existing evidence on the effect of 4-aminopyridine (4-AP) as a symptomatic treatment of decreased walking capacity in patients with multiple sclerosis (MS) when administered as an immediate release compound and a slow release compound. It summarizes existing evidence on the basic mechanisms of 4-AP from experimental studies and evidence on the clinical use of the compound. A systematic literature search was conducted of the following databases: PubMed and EMBASE. Thirty-five studies were included in the review divided into 16 experimental studies, two clinical studies with paraclinical endpoints and 17 clinical studies with clinical endpoints. Animal studies show that 4-AP can improve impulse conduction through demyelinated lesions. In patients with MS this translates into improved walking speed and muscle strength of the lower extremities in a subset of patients at a level that is often of clinical relevance. Phase III trials demonstrate approximately 25% increase in walking speed in roughly 40% and improved muscle strength in the lower extremities. Furthermore, 4-AP might have an effect on other domains such as cognition, upper extremity function and bowel and bladder, but this warrants further investigation. Side effects are mainly mild to moderate, consisting primarily of paraesthesia, dizziness, nausea/vomiting, falls/balance disorders, insomnia, urinary tract infections and asthenia. Side effects are worse when administered intravenously and when administered as an immediate release compound. Serious adverse events are rarely seen in the marketed clinical dosages. In conclusion, 4-AP is easy and safe to use. Slow release 4-AP shows more robust clinical effects and a more beneficial side-effect profile than immediate release 4-AP.

Responsiveness and clinically meaningful improvement, according to disability level, of five walking measures after rehabilitation in multiple sclerosis: a European multicenter study

BACKGROUND

Evaluation of treatment effects on walking requires appropriate and responsive outcome measures.

OBJECTIVES

To determine responsiveness of 5 walking measures and provide reference values for clinically meaningful improvements, according to disability level, in persons with multiple sclerosis (pwMS).

METHODS

Walking tests were measured pre- and postrehabilitation in 290 pwMS from 17 European centers. Combined anchor- and distribution-based methods determined responsiveness of objective short and long walking capacity tests (Timed 25-Foot Walk [T25FW] and 2- and 6-Minute Walk Tests [2MWT and 6MWT] and of the patient-reported Multiple Sclerosis Walking Scale-12 [MSWS-12]). A global rating of change scale, from patients' and therapists' perspective, was used as external criteria to determine the area under the receiver operating characteristic curve (AUC), minimally important change (MIC), and smallest real change (SRC). Patients were stratified into disability subgroups (Expanded Disability Status Scale score ≤4 [n = 98], >4 [n = 186]).

RESULTS

MSWS-12, 2MWT, and 6MWT were more responsive (AUC 0.64-0.73) than T25FW (0.50-0.63), especially in moderate to severely disabled pwMS. Clinically meaningful changes (MICs) from patient and therapist perspective were -10.4 and -11.4 for MSWS-12 (P < .01), 9.6 m and 6.8 m for 2MWT (P < .05), and 21.6 m (P < .05) and 9.1 m (P = .3) for 6MWT. In subgroups, MIC was significant from patient perspective for 2MWT (10.8 m) and from therapist perspective for MSWS-12 (-10.7) in mildly disabled pwMS. In moderate to severely disabled pwMS, MIC was significant for MSWS-12 (-14.1 and -11.9).

CONCLUSIONS

Long walking tests and patient-reported MSWS-12 were more appropriate than short walking tests in detecting clinically meaningful improvement after physical rehabilitation, particularly the MSWS-12 for moderate to severely disabled pwMS.

Clinically meaningful performance benchmarks in MS: timed 25-foot walk and the real world

OBJECTIVE

Identify and validate clinically meaningful Timed 25-Foot Walk (T25FW) performance benchmarks in individuals living with multiple sclerosis (MS).

METHODS

Cross-sectional study of 159 MS patients first identified candidate T25FW benchmarks. To characterize the clinical meaningfulness of T25FW benchmarks, we ascertained their relationships to real-life anchors, functional independence, and physiologic measurements of gait and disease progression. Candidate T25FW benchmarks were then prospectively validated in 95 subjects using 13 measures of ambulation and cognition, patient-reported outcomes, and optical coherence tomography.

RESULTS

T25FW of 6 to 7.99 seconds was associated with a change in occupation due to MS, occupational disability, walking with a cane, and needing "some help" with instrumental activities of daily living; T25FW ≥8 seconds was associated with collecting Supplemental Security Income and government health care, walking with a walker, and inability to do instrumental activities of daily living. During prospective benchmark validation, we trichotomized data by T25FW benchmarks (<6 seconds, 6-7.99 seconds, and ≥8 seconds) and found group main effects on 12 of 13 objective and subjective measures (p < 0.05).

CONCLUSIONS

Using a cross-sectional design, we identified 2 clinically meaningful T25FW benchmarks of ≥6 seconds (6-7.99) and ≥8 seconds. Longitudinal and larger studies are needed to confirm the clinical utility and relevance of these proposed T25FW benchmarks and to parse out whether there are additional benchmarks in the lower (<6 seconds) and higher (>10 seconds) ranges of performance.

Recommendations for the use of prolonged-release fampridine in patients with multiple sclerosis (MS)

Prolonged-release fampridine (fampridine PR) is a potassium channel blocker that improves conductivity of signal on demyelinated axons in central nervous system. Fampridine PR has been approved to improve speed of walking in patients with multiple sclerosis. This statement provides a brief summary of data on fampridine PR and recommendations on practical use of the medication in clinical practice, prediction, and evaluation of response to treatment and patient management.

Estimation of the effect of dalfampridine-ER on health utility by mapping the MSWS-12 to the EQ-5D in multiple sclerosis patients

Background

Trials have not assessed the effect of dalfampridine-extended release (dalfampridine-ER) on health utility. We sought to evaluate the effect of dalfampridine-ER tablets (prolonged-release fampridine in Europe) on health utility in patients with multiple sclerosis (MS) by mapping subjects’ individual item scores from the 12-Item Multiple Sclerosis Walking Scale (MSWS-12) onto the Euroqol 5-Dimension (EQ-5D) health utility index.

Methods

Data from study MS-F203, a randomized trial of dalfampridine-ER tablets, 10 mg twice daily, in patients with MS, were used to calculate the health utility scores with two MSWS-12 to EQ-5D mapping equations (one derived in a North American [NA] registry, the other a United Kingdom [UK] registry). MS-F203 participants were categorized as dalfampridine-ER 20%-responders (achieving ≥20% improvement on the Timed 25-Foot Walk), dalfampridine-ER 20%-nonresponders (<20% improvement), or placebo patients. Mean change in health utility scores from baseline to each double-blind treatment evaluation (visits 3-6 occurring at post-randomization weeks 2, 6, 10, and 14) and each off-drug follow-up evaluation (visits 7-8 occurring at weeks 16 and 18) were calculated and reported as effect sizes (ESs).

Results

Using the NA-derived equation, dalfampridine-ER 20%-responders demonstrated improvement in health utility vs. placebo; starting at week 6 (mean difference in ES = 0.44, p = 0.002) and maintained at weeks 10 (ES = 0.41, p = 0.01) and 14 (ES = 0.71, p < 0.001). These improvements were no longer evident after dalfampridine-ER was discontinued (p > 0.05 at weeks 16 and 18). Dalfampridine-ER 20%-nonresponders did not show improvement vs. placebo at any visit (p > 0.05 for all). When using the UK-derived equation, improvement was seen in dalfampridine-ER 20%-responders vs. placebo at weeks 2, 6, 10, and 14 (ESs = 0.49, 0.55, 0.59, and 0.99; p < 0.03 for all), but not when dalfampridine-ER was discontinued (weeks 16 and 18; p > 0.05 for both). Dalfampridine-ER 20%-nonresponders showed no improvement at any visit (p > 0.05 for all).

Conclusion

Regardless of the equation used, dalfampridine-ER response was associated with an improvement in health utility.

Enhancing neural transmission in multiple sclerosis (4-aminopyridine therapy)

Enhancing neural transmission by improving axonal conduction and synaptic neurotransmitter release is a novel strategy to improve symptoms in multiple sclerosis. Dalfampridine (4-aminopyridine extended-release) is a first-in-class medication that targets the damaged nervous system through blockage of voltage-gated potassium channels. Through a series of clinical trials, dalfampridine (dosed at 10 mg twice daily) has been found to improve walking speed by approximately 25 % on average in one third of individuals with multiple sclerosis regardless of disease stage. Furthermore, it significantly improves patients' perception of their ambulatory disability and may improve lower extremity strength. Given the mechanism of action, the most serious adverse effect is its pro-convulsant property, which occurs more frequently at high serum concentrations. The most common adverse events include increased falls, urinary tract infections, dizziness, insomnia, and headaches. Despite these potential side-effects, the vast majority of individuals who derive benefit continue on the treatment. The exact mechanism of action is uncertain, as is the reason for response variability. The medication serves as proof-of-concept that targeting axonal transmission can improve disability in multiple sclerosis.

Extended-release dalfampridine in the management of multiple-sclerosis-related walking impairment

Multiple sclerosis is an inflammatory demyelinating disease of the central nervous system that causes neurological impairment in young adults. As part of the disease, ambulation remains one of the most disabling features of multiple sclerosis. Extended-release dalfampridine is a long-acting form of 4-aminopyridine that has been shown in two phase III trials to increase ambulation speed in a subset of patients with multiple sclerosis (timed walk responders). The primary endpoint of these studies was 'responder status', analyzing difference in the proportion of timed walk responders between extended-release dalfampridine and placebo groups. Extended-release dalfampridine exerts its effects by inhibiting voltage-activated K(+) channels and has been previously demonstrated to improve action potential propagation in demyelinated nerve fibers in vitro. Side effects of extended-release dalfampridine include increased urinary tract infections, insomnia, headache, asthenia, dizziness, back pain, and paresthesias. Rare seizure events are also reported on the approved dose of 10 mg every 12 h. In this review we will summarize the results of key phase II and phase III trials of extended-release dalfampridine, its safety, and potential use in patients with multiple sclerosis.

Assessing walking disability in multiple sclerosis

Most patients with multiple sclerosis (MS) eventually experience walking disability. The objective of this review was to evaluate the clinical utility of measures specific for walking in MS. Walking assessments had high reliability and were correlated with related measures, including the 12-item multiple sclerosis walking scale (MSWS-12). Shorter timed walking tests (Timed 25-foot Walk (T25FW), 10-metre Timed Walk, 30-metre Timed Walk) measure overall walking disability and are best suited for clinical settings, whereas longer timed or distance tests (100-metre Timed Walk, 6-minute Walk Test, 2-minute Walk Test) are better for the assessment of walking fatigability, distance limitations and functional capacity. The MSWS-12 measures different, but related, aspects of walking than the objective tests. The T25FW is the best characterised objective measure of walking disability and can be used across a wide range of walking disabilities. Additional work is needed to fully characterise the other objective walking assessments in MS.