Development of a gait module to complement the 12-item Multiple Sclerosis Walking Scale: a mixed methods study

Background and objective

The 12-item Multiple Sclerosis Walking Scale (MSWS-12) is a patient-reported outcome instrument that quantifies the progressive loss of walking ability from the patient perspective. However, previous psychometric analyses indicated floor and ceiling effects across the multiple sclerosis severity spectrum. This study aimed to address floor effects by creating a gait module that can be used in conjunction with the MSWS-12 for better measurement of treatment benefit in the higher functioning multiple sclerosis population.

Methods

We used a step-wise mixed methods study design, with relapsing-remitting multiple sclerosis patients (wave 1, n=88; wave 2, n=30), combining qualitative (concept elicitation and cognitive debriefing interviews) and quantitative (Rasch Measurement Theory) data collection and analytical techniques and consultation interviews with three neurologists specializing in multiple sclerosis.

Results

Thirty-seven walking ability concepts were identified, and a five-domain conceptual framework was created. Draft items were generated and refined with patient and neurologist input. Draft items covered gait-related concepts such as dragging, shuffling, limping, tripping and falling. Rasch measurement theory psychometric analysis indicated administering MSWS-12 plus gait items improved measurement precision in targeted populations with better walking ability.

Conclusion

Study findings indicate that new gait items could improve sensitivity to detect clinical change in walking ability for higher functioning multiple sclerosis patients.

Addressing the targeting range of the ABILHAND-56 in relapsing-remitting multiple sclerosis: A mixed methods psychometric study

Background

ABILHAND, a manual ability patient-reported outcome instrument originally developed for stroke patients, has been used in multiple sclerosis clinical trials; however, psychometric analyses indicated the measure’s limited measurement range and precision in higher-functioning multiple sclerosis patients.

Objective

The purpose of this study was to identify candidate items to expand the measurement range of the ABILHAND-56, thus improving its ability to detect differences in manual ability in higher-functioning multiple sclerosis patients.

Methods

A step-wise mixed methods design strategy was used, comprising two waves of patient interviews, a combination of qualitative (concept elicitation and cognitive debriefing) and quantitative (Rasch measurement theory) analytic techniques, and consultation interviews with three clinical neurologists specializing in multiple sclerosis.

Results

Original ABILHAND was well understood in this context of use. Eighty-two new manual ability concepts were identified. Draft supplementary items were generated and refined with patient and neurologist input. Rasch measurement theory psychometric analysis indicated supplementary items improved targeting to higher-functioning multiple sclerosis patients and measurement precision. The final pool of Early Multiple Sclerosis Manual Ability items comprises 20 items.

Conclusion

The synthesis of qualitative and quantitative methods used in this study improves the ABILHAND content validity to more effectively identify manual ability changes in early multiple sclerosis and potentially help determine treatment effect in higher-functioning patients in clinical trials.

Effect of natalizumab on disease progression in secondary progressive multiple sclerosis (ASCEND): a phase 3, randomised, double-blind, placebo-controlled trial with an open-label extension

BACKGROUND

Although several disease-modifying treatments are available for relapsing multiple sclerosis, treatment effects have been more modest in progressive multiple sclerosis and have been observed particularly in actively relapsing subgroups or those with lesion activity on imaging. We sought to assess whether natalizumab slows disease progression in secondary progressive multiple sclerosis, independent of relapses.

METHODS

ASCEND was a phase 3, randomised, double-blind, placebo-controlled trial (part 1) with an optional 2 year open-label extension (part 2). Enrolled patients aged 18-58 years were natalizumab-naive and had secondary progressive multiple sclerosis for 2 years or more, disability progression unrelated to relapses in the previous year, and Expanded Disability Status Scale (EDSS) scores of 3·0-6·5. In part 1, patients from 163 sites in 17 countries were randomly assigned (1:1) to receive 300 mg intravenous natalizumab or placebo every 4 weeks for 2 years. Patients were stratified by site and by EDSS score (3·0-5·5 vs 6·0-6·5). Patients completing part 1 could enrol in part 2, in which all patients received natalizumab every 4 weeks until the end of the study. Throughout both parts, patients and staff were masked to the treatment received in part 1. The primary outcome in part 1 was the proportion of patients with sustained disability progression, assessed by one or more of three measures: the EDSS, Timed 25-Foot Walk (T25FW), and 9-Hole Peg Test (9HPT). The primary outcome in part 2 was the incidence of adverse events and serious adverse events. Efficacy and safety analyses were done in the intention-to-treat population. This trial is registered with ClinicalTrials.gov, number NCT01416181.

FINDINGS

Between Sept 13, 2011, and July 16, 2015, 889 patients were randomly assigned (n=440 to the natalizumab group, n=449 to the placebo group). In part 1, 195 (44%) of 439 natalizumab-treated patients and 214 (48%) of 448 placebo-treated patients had confirmed disability progression (odds ratio [OR] 0·86; 95% CI 0·66-1·13; p=0·287). No treatment effect was observed on the EDSS (OR 1·06, 95% CI 0·74-1·53; nominal p=0·753) or the T25FW (0·98, 0·74-1·30; nominal p=0·914) components of the primary outcome. However, natalizumab treatment reduced 9HPT progression (OR 0·56, 95% CI 0·40-0·80; nominal p=0·001). In part 1, 100 (22%) placebo-treated and 90 (20%) natalizumab-treated patients had serious adverse events. In part 2, 291 natalizumab-continuing patients and 274 natalizumab-naive patients received natalizumab (median follow-up 160 weeks [range 108-221]). Serious adverse events occurred in 39 (13%) patients continuing natalizumab and in 24 (9%) patients initiating natalizumab. Two deaths occurred in part 1, neither of which was considered related to study treatment. No progressive multifocal leukoencephalopathy occurred.

INTERPRETATION

Natalizumab treatment for secondary progressive multiple sclerosis did not reduce progression on the primary multicomponent disability endpoint in part 1, but it did reduce progression on its upper-limb component. Longer-term trials are needed to assess whether treatment of secondary progressive multiple sclerosis might produce benefits on additional disability components.

FUNDING

Biogen.

Real-world walking in multiple sclerosis: Separating capacity from behavior

BACKGROUND

Habitual physical activity (HPA) measurement addresses the impact of MS on real-world walking, yet its interpretation is confounded by the competing influences of MS-associated walking capacity and physical activity behaviors.

OBJECTIVE

To develop specific measures of MS-associated walking capacity through statistically sophisticated HPA analysis, thereby more precisely defining the real-world impact of disease.

METHODS

Eighty-eight MS and 38 control subjects completed timed walks and patient-reported outcomes in clinic, then wore an accelerometer for 7days. HPA was analyzed with several new statistics, including the maximum step rate (MSR) and habitual walking step rate (HWSR), along with conventional methods, including average daily steps. HPA statistics were validated using clinical walking outcomes.

RESULTS

The six-minute walk (6MW) step rate correlated most strongly with MSR (r=0.863, p<10^-25) and HWSR (r=0.815, p<10^-11) rather than average daily steps (r=0.676, p<10^-11). The combination of MSR and HWSR correlated more strongly with the 6MW step rate than either measure alone (r=0.884, p<10^-14). The MSR overestimated the 6MW step rate (μ=10.4, p<10^-7), whereas the HWSR underestimated it (μ=-18.2, p<10^-19).

CONCLUSIONS

Conventional HPA statistics are poor measures of capacity due to variability in activity behaviors. The MSR and HWSR are valid, specific measures of real-world capacity which capture subjects' highest step rate and preferred step rate, respectively.

Breastfeeding During Infancy Is Associated With a Lower Future Risk of Pediatric Multiple Sclerosis

BACKGROUND

Risk of multiple sclerosis (MS) is influenced by environment and genetics. Infant breastfeeding appears protective against some childhood autoimmune disorders, but its impact on risk of MS in childhood is unknown. The objective of this study is to analyze the association of breastfeeding in infancy on future risk of pediatric-onset MS.

BASIC PROCEDURES

Biological mothers of 36 consecutive pediatric-onset MS patients completed a questionnaire on history of breastfeeding and various birth and demographic factors. The control group consisted of 72 otherwise healthy patients with a diagnosis of migraine and normal brain magnetic resonance imaging obtained less than 12 months before enrollment. Inverse probability of treatment weighting was used to reduce selection bias and balance the covariates between breastfed and non-breastfed children.

MAIN FINDINGS

Demographics (with the exception of body mass index) and birth factors were not significantly different between groups. Whereas 36% of cases were breastfed, 71% of controls were breastfed (P = 0.001). The median duration of breastfeeding was 0 weeks (range: 0 to 40 weeks) for cases and 16 weeks (range: 0 to 216 weeks) for controls. Lack of infant breastfeeding was associated with future diagnosis of pediatric-onset MS (odds ratio = 4.43; 95% confidence interval, 1.68 to 11.71; P = 0.003). This association remained significant after correcting for covariates, such as body mass index and age at diagnosis.

CONCLUSIONS

These data demonstrate that absence of infant breastfeeding has an association with an increased risk of pediatric-onset MS diagnosis.

Glucocorticoid-associated blood glucose response and MS relapse recovery

OBJECTIVE

To determine the relationship between MS relapse recovery and blood glucose (BG) response to IV methylprednisolone (IVMP) treatment.

METHODS

We retrospectively identified 36 patients with MS admitted for IVMP treatment of acute relapse who had adequate data to characterize BG response, relapse severity, and recovery. The relationship between glucocorticoid-associated nonfasting BG (NFBG) and relapse recovery was assessed.

RESULTS

Highest recorded nonfasting BG (maximum NFBG [maxNFBG]) values were significantly higher in patients with MS without relapse recovery compared with those with recovery (271 ± 68 vs 209 ± 48 mg/dL, respectively; p = 0.0045). After adjusting for relapse severity, MS patients with maxNFBG below the group median were 6 times (OR = 6.01; 95% CI, 1.08-33.40; p = 0.040) more likely to experience relapse recovery than those with maxNFBG above the group median. In a multiple regression model adjusting for age, sex, and relapse severity, a 1-mg/dL increase in the maxNFBG was associated with 4.5% decrease in the probability of recovery (OR = 0.955; 95% CI, 0.928-0.983; p = 0.002).

CONCLUSIONS

These findings suggest that higher glucocorticoid-associated NFBG values in acutely relapsing patients with MS are associated with diminished probability of recovery. This relationship could reflect steroid-associated hyperglycemia and/or insulin resistance, defects in non-steroid-associated (e.g., prerelapse) glucose metabolism, or both. This study included only those admitted for an MS relapse, and it is this subset of patients for whom these findings may be most relevant. A prospective study to evaluate glucose regulation and MS relapse recovery in a broader outpatient MS population is under way.

The MSOAC approach to developing performance outcomes to measure and monitor multiple sclerosis disability

Background:

The Multiple Sclerosis Outcome Assessments Consortium (MSOAC) was formed by the National MS Society to develop improved measures of multiple sclerosis (MS)-related disability.

Objectives:

(1) To assess the current literature and available data on functional performance outcome measures (PerfOs) and (2) to determine suitability of using PerfOs to quantify MS disability in MS clinical trials.

Methods:

(1) Identify disability dimensions common in MS; (2) conduct a comprehensive literature review of measures for those dimensions; (3) develop an MS Clinical Data Interchange Standards Consortium (CDISC) data standard; (4) create a database of standardized, pooled clinical trial data; (5) analyze the pooled data to assess psychometric properties of candidate measures; and (6) work with regulatory agencies to use the measures as primary or secondary outcomes in MS clinical trials.

Conclusion:

Considerable data exist supporting measures of the functional domains ambulation, manual dexterity, vision, and cognition. A CDISC standard for MS (http://www.cdisc.org/therapeutic#MS) was published, allowing pooling of clinical trial data. MSOAC member organizations contributed clinical data from 16 trials, including 14,370 subjects. Data from placebo-arm subjects are available to qualified researchers. This integrated, standardized dataset is being analyzed to support qualification of disability endpoints by regulatory agencies.

Relationship between gait variables and domains of neurologic dysfunction in multiple sclerosis using six-minute walk test

Most multiple sclerosis (MS) patients eventually suffer from mobility impairment, and thus it is critical that walking disability in MS be accurately assessed. The six-minute walk test (6MWT), a reliable MS measure, is traditionally used to determine the distance covered in six minutes using a standard protocol. With the availability of body sensor networks (BSNs), researchers are interested in leveraging BSN data for finding new gait assessment anchors for improved separability performance. Further, current methods for gait assessments are insufficient since assessments are absolute, performed by comparing outcomes to the statistical norms established from diverse patient data despite natural inter-patient variability. For example, walking at a slower pace may be a personal trait rather than a fatigue-induced impact in MS. Thus instead of using actual values, changes in gait features during a 6MWT can be used to draw clinical conclusions and remove inter-subject variability. We use 6MWT gait time series BSN data of MS subjects to determine changes in their gait speed and gait cycle length variance over six minutes. We also determine the relationships between these variables and three subjective assessments, namely functional systems scores, modified fatigue impact scale, and multiple sclerosis walking scale. These relationships are important in order to validate features and make them clinically meaningful for a doctor. In MS, feelings of fatigue can occur more often, and have a greater impact on a subject's daily life. The results show that MS patients who reported high motor-related fatigue slowed down and had high gait cycle length variance in the last minute of the test, in contrast to those on whom fatigue had minimal impact, enhancing the separability between MS subjects of varied disabilities based on their scores. It is also observed that FSS components related to coordination, balance, and physical activities show strong correlation with gait parameters.

Identification and validation of clinically meaningful benchmarks in the 12-item Multiple Sclerosis Walking Scale

BACKGROUND

The 12-item Multiple Sclerosis Walking Scale (12-MSWS) is a validated questionnaire which assessed walking function; it has been widely adopted in multiple sclerosis (MS) clinical research.

OBJECTIVE

Identify and validate clinically meaningful 12-MSWS benchmarks in MS.

METHODS

Cross-sectional study of 159 MS patients permitted identification of clinically meaningful 12-MSWS benchmarks based on their relationship to real-life anchors. Identified 12-MSWS benchmarks were then validated in a second population of 96 subjects using measures of ambulation, cognition, and patient-reported outcomes.

RESULTS

12-MSWS score of 0-24.99 was associated with working outside the home and assistance-free mobility; 25-49.99 was associated with gait disability and difficulty doing housework; 50-74.99 was associated with unemployment, government healthcare, cane use, and difficulty performing instrumental activities of daily living (IADLs); and 75-100 was associated with change in occupation due to walking, mobility impairment requiring bilateral assistance, and inability to perform IADLs. During the validation step, strong linear associations were identified between 12-MSWS benchmarks and other MS-related disability outcome measures, including ambulatory and non-ambulatory measures.

CONCLUSION

We have identified clinically meaningful 12-MSWS benchmarks which define four groups differentiated by increasing levels of mobility impairment and associated loss of functional independence. These data provide insight into how 12-MSWS translate to meaningful functional limitations in MS.

Quantifying six-minute walk induced gait deterioration with inertial sensors in multiple sclerosis subjects

BACKGROUND

The six-minute walk (6MW) is a common walking outcome in multiple sclerosis (MS) thought to measure fatigability in addition to overall walking disability. However, direct evidence of 6MW induced gait deterioration is limited by the difficulty of measuring qualitative changes in walking.

OBJECTIVES

This study aims to (1) define and validate a measure of fatigue-related gait deterioration based on data from body-worn sensors; and (2) use this measure to detect gait deterioration induced by the 6MW.

METHODS

Gait deterioration was assessed using the Warp Score, a measure of similarity between gait cycles based on dynamic time warping (DTW). Cycles from later minutes were compared to baseline cycles in 89 subjects with MS and 29 controls. Correlation, corrected (partial) correlation, and linear regression were used to quantify relationships to walking and fatigue outcomes.

RESULTS

Warp Scores rose between minute 3 and minute 6 in subjects with mild and moderate disability (p<0.001). Statistically significant correlations (p<0.001) to the MS walking scale (MSWS-12), modified fatigue impact scale (MFIS) physical subscale, and cerebellar and pyramidal functional system scores (FSS) were observed even after controlling for walking speed. Regression of MSWS-12 scores on Warp Scores and walking speed explained 73.9% of response variance. Correlations to individual MSWS-12 and MFIS items strongly suggest a relationship to fatigability.

CONCLUSION

The Warp Score has been validated in MS subjects as an objective measure of fatigue-related gait deterioration. Progressive changes to gait cycles induced by the 6MW often appeared in later minutes, supporting the importance of sustained walking in clinical assessment.

Fatigue and fluid hydration status in multiple sclerosis: A hypothesis

BACKGROUND

Fatigue is a prevalent and functionally disabling symptom for individuals living with multiple sclerosis (MS) which is poorly understood and multifactorial in etiology. Bladder dysfunction is another common MS symptom which limits social engagement and quality of life. To manage bladder issues, individuals with MS tend to limit their fluid intake, which may contribute to a low-hydration (LoH) state and fatigue.

OBJECTIVE

To evaluate the relationship between patient-reported MS fatigue, bladder dysfunction, and hydration status.

METHODS

We performed a prospective cross-sectional study in 50 women with MS. Participants submitted a random urine sample and completed several fatigue-related surveys. Using a urine specific gravity (USG) threshold of 1.015, we classified MS subjects into two groups: high-hydration (HiH) and LoH states.

RESULTS

LoH status was more common in MS subjects with bladder dysfunction. Statistically significant differences in self-reported Fatigue Performance Scale were observed between HiH and LoH subjects (p = 0.022). USG was significantly correlated with fatigue as measured by the MS Fatigue Severity Scale (FSS) score (r = 0.328, p = 0.020).

CONCLUSION

Hydration status correlates with self-reported fatigue, with lower fatigue scores found in those with HiH status (USG < 1.015).

The EDSS-Plus, an improved endpoint for disability progression in secondary progressive multiple sclerosis

BACKGROUND

The Expanded Disability Status Scale (EDSS) has wide scientific and regulatory precedent but limited ability to detect clinically relevant disability progression in secondary progressive multiple sclerosis (SPMS) patients, partly due to a lack of meaningful measurement of short-distance ambulatory and upper-extremity function.

OBJECTIVE

To present a rationale for a composite endpoint adding the timed 25-foot walk (T25FW) and 9-Hole Peg Test (9HPT) to EDSS for SPMS disability progression assessment.

METHODS

Using the International Multiple Sclerosis Secondary Progressive Avonex Clinical Trial (IMPACT) placebo arm ( n = 215) data, we analyzed disability progression using a novel progression endpoint, "EDSS-Plus," defined as progression on ⩾1 of 3 components (EDSS, T25FW, and/or 9HPT) confirmed ⩾24 weeks apart and with a ⩾20% minimum threshold change for T25FW and 9HPT.

RESULTS

Over 2 years, subjects classified as T25FW, 9HPT (dominant hand), or 9HPT (non-dominant hand) progressors worsened on average by 103.4%, 69.0%, and 59.2%, respectively, while non-progressors' times remained largely unchanged. Using EDSS-Plus, 59.5% of the patients had 24-week confirmed disability progression versus 24.7% (EDSS), 41.9% (T25FW), and 34.4% (9HPT (either hand)) on each component alone.

CONCLUSION

The 24-week confirmed minimum worsening of ⩾20% for T25FW and 9HPT clearly separates SPMS progressors from non-progressors. We propose that EDSS-Plus may represent an improved endpoint to identify SPMS disability progression.

Causality Analysis of Inertial Body Sensors for Multiple Sclerosis Diagnostic Enhancement

Inertial body sensors have emerged in recent years as an effective tool for evaluating mobility impairment resulting from various diseases, disorders, and injuries. For example, body sensors have been used in 6-min walk (6 MW) tests for multiple sclerosis (MS) patients to identify gait features useful in the study, diagnosis, and tracking of the disease. However, most studies to date have focused on features localized to the lower or upper extremities and do not provide a holistic assessment of mobility. This paper presents a causality analysis method focused on the coordination between extremities to identify subtle whole-body mobility impairment that may aid disease diagnosis. This method was developed for and utilized in an MS pilot study with 41 subjects (28 persons with MS (PwMS) and 13 healthy controls) performing 6 MW tests. Compared with existing methods, the causality analysis provided better discrimination between healthy controls and PwMS and a deeper understanding of MS disease impact on mobility.

The e-MSWS-12: improving the multiple sclerosis walking scale using item response theory

BACKGROUND

The Multiple Sclerosis Walking Scale (MSWS-12) is the predominant patient-reported measure of multiple sclerosis (MS) -elated walking ability, yet it had not been analyzed using item response theory (IRT), the emerging standard for patient-reported outcome (PRO) validation. This study aims to reduce MSWS-12 measurement error and facilitate computerized adaptive testing by creating an IRT model of the MSWS-12 and distributing it online.

METHODS

MSWS-12 responses from 284 subjects with MS were collected by mail and used to fit and compare several IRT models. Following model selection and assessment, subpopulations based on age and sex were tested for differential item functioning (DIF).

RESULTS

Model comparison favored a one-dimensional graded response model (GRM). This model met fit criteria and explained 87 % of response variance. The performance of each MSWS-12 item was characterized using category response curves (CRCs) and item information. IRT-based MSWS-12 scores correlated with traditional MSWS-12 scores (r = 0.99) and timed 25-foot walk (T25FW) speed (r =  -0.70). Item 2 showed DIF based on age (χ ² = 19.02, df = 5, p < 0.01), and Item 11 showed DIF based on sex (χ ² = 13.76, df = 5, p = 0.02).

CONCLUSIONS

MSWS-12 measurement error depends on walking ability, but could be lowered by improving or replacing items with low information or DIF. The e-MSWS-12 includes IRT-based scoring, error checking, and an estimated T25FW derived from MSWS-12 responses. It is available at https://ms-irt.shinyapps.io/e-MSWS-12 .

Evaluation of Dalfampridine Extended Release 5 and 10 mg in Multiple Sclerosis: A Randomized Controlled Trial

BACKGROUND

Dalfampridine extended-release (ER) tablets, 10 mg twice daily, have been shown to improve walking in people with multiple sclerosis. We evaluated the safety and efficacy of dalfampridine-ER 5 mg compared with 10 mg.

METHODS

Patients were randomized to double-blind treatment with twice-daily dalfampridine-ER tablets, 5 mg (n = 144) or 10 mg (n = 143), or placebo (n = 143) for 4 weeks. Primary efficacy endpoint was change from baseline walking speed by the Timed 25-Foot Walk 3 to 4 hours after the last dose. At 40% of sites, 2-week change from baseline walking distance was measured by the 6-Minute Walk test.

RESULTS

At 4 weeks, walking speed changes from baseline were 0.363, 0.423, and 0.478 ft/s (placebo, dalfampridine-ER 5 mg, and dalfampridine-ER 10 mg, respectively [P = NS]). Post hoc analysis of average changes between pretreatment and on-treatment showed that relative to placebo, only dalfampridine-ER 10 mg demonstrated a significant increase in walking speed (mean ± SE): 0.443 ± 0.042 ft/s versus 0.303 ± 0.038 ft/s (P = .014). Improvement in 6-Minute Walk distance was significantly greater with dalfampridine-ER 10 mg (128.6 ft, P = .014) but not with 5 mg (76.8 ft, P = .308) relative to placebo (41.7 ft). Adverse events were consistent with previous studies. No seizures were reported.

CONCLUSIONS

Dalfampridine-ER 5 and 10 mg twice daily did not demonstrate efficacy on the planned endpoint. Post hoc analyses demonstrated significant increases in walking speed relative to placebo with dalfampridine-ER 10 mg. No new safety signals were observed.

Overview and safety of fingolimod hydrochloride use in patients with multiple sclerosis

INTRODUCTION

Fingolimod (Gilenya®, FTY720) is an oral sphingosine-1-phosphate analogue that was approved by the FDA in 2010 for the treatment of relapsing forms of multiple sclerosis (MS). Fingolimod's mechanism of action is primarily related to lymphocyte sequestration in primary and secondary lymphoid tissues. Phase III trials demonstrated a reduction in annualized relapse rate and MRI progression in fingolimod-treated subjects compared with both placebo and IFN-β-treated subjects. Frequent adverse effects include fatigue, gastrointestinal disturbance, headache and upper respiratory tract infection. More serious, but rare, adverse events associated with fingolimod include atrioventricular block, symptomatic bradycardia, herpetic viral infections and macular edema.

AREAS COVERED

We discuss the mechanism of action, pharmacokinetics, clinical efficacy and safety profile of fingolimod in patients with relapsing MS.

EXPERT OPINION

Fingolimod is an effective treatment for relapsing MS and its oral route of administration may be preferred by some. Fingolimod is generally well tolerated but requires diligence in patient selection and monitoring. Additional information is needed regarding risk of infection, malignancy and rebound disease with long-term use of fingolimod.

Alemtuzumab for the treatment of relapsing-remitting multiple sclerosis: a review of its clinical pharmacology, efficacy and safety

Multiple sclerosis (MS) is an inflammatory condition of the CNS presumably induced by an environmental trigger(s) in a genetically susceptible individual. Inflammation is prominent and most susceptible to intervention early in MS, so early treatment with disease-modifying therapies is recommended to reduce relapses and new MRI activity (both markers of inflammation) with the goal of delaying disability progression. Unfortunately, the response to the disease-modifying therapies is variable and often falls short of stopping observable disease activity, so the search for more effective agents continues. Alemtuzumab is a monoclonal antibody against CD52 that has exhibited significant efficacy throughout its clinical trial program in MS; uniquely, some of the studies have demonstrated a sustained reduction in disability in MS patients. Countering this impressive efficacy is an associated high risk of autoimmune events (especially thyroid) and concerns for infection or malignancy given prolonged immunosuppression after treatment with alemtuzumab.

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.

Clinical importance of steps taken per day among persons with multiple sclerosis

Background

The number of steps taken per day (steps/day) provides a reliable and valid outcome of free-living walking behavior in persons with multiple sclerosis (MS).

Objective

This study examined the clinical meaningfulness of steps/day using the minimal clinically important difference (MCID) value across stages representing the developing impact of MS.

Methods

This study was a secondary analysis of de-identified data from 15 investigations totaling 786 persons with MS and 157 healthy controls. All participants provided demographic information and wore an accelerometer or pedometer during the waking hours of a 7-day period. Those with MS further provided real-life, health, and clinical information and completed the Multiple Sclerosis Walking Scale-12 (MSWS-12) and Patient Determined Disease Steps (PDDS) scale. MCID estimates were based on regression analyses and analysis of variance for between group differences.

Results

The mean MCID from self-report scales that capture subtle changes in ambulation (1-point change in PDSS scores and 10-point change in MSWS-12 scores) was 779 steps/day (14% of mean score for MS sample); the mean MCID for clinical/health outcomes (MS type, duration, weight status) was 1,455 steps/day (26% of mean score for MS sample); real-life anchors (unemployment, divorce, assistive device use) resulted in a mean MCID of 2,580 steps/day (45% of mean score for MS sample); and the MCID for the cumulative impact of MS (MS vs. control) was 2,747 steps/day (48% of mean score for MS sample).

Conclusion

The change in motion sensor output of ∼800 steps/day appears to represent a lower-bound estimate of clinically meaningful change in free-living walking behavior in interventions of MS.

Evidence for the different physiological significance of the 6- and 2-minute walk tests in multiple sclerosis

BACKGROUND

Researchers have recently advocated for the 2-minute walk (2MW) as an alternative for the 6-minute walk (6MW) to assess long distance ambulation in persons with multiple sclerosis (MS). This recommendation has not been based on physiological considerations such as the rate of oxygen consumption (V·O2) over the 6MW range.

OBJECTIVE

This study examined the pattern of change in V·O2 over the range of the 6MW in a large sample of persons with MS who varied as a function of disability status.

METHOD

Ninety-five persons with clinically-definite MS underwent a neurological examination for generating an Expanded Disability Status Scale (EDSS) score, and then completion of the 6MW protocol while wearing a portable metabolic unit and an accelerometer.

RESULTS

There was a time main effect on V·O2 during the 6MW (p=.0001) such that V·O2 increased significantly every 30 seconds over the first 3 minutes of the 6MW, and then remained stable over the second 3 minutes of the 6MW. This occurred despite no change in cadence across the 6MW (p=.84).

CONCLUSIONS

The pattern of change in V·O2 indicates that there are different metabolic systems providing energy for ambulation during the 6MW in MS subjects and steady state aerobic metabolism is reached during the last 3 minutes of the 6MW. By extension, the first 3 minutes would represent a test of mixed aerobic and anaerobic work, whereas the second 3 minutes would represent a test of aerobic work during walking.