Cognitive processing speed has minimal influence on the construct validity of Multiple Sclerosis Walking Scale-12 scores

Validation of scores from a telephone administered multiple sclerosis walking scale-12 in persons with multiple sclerosis

BACKGROUND

The Multiple Sclerosis Walking Scale-12 (MSWS-12) has typically been delivered through paper-and-pencil or computer-based administration.

PURPOSE

This study examined the validity of inferences from scores derived via a telephone administration of the MSWS-12 applied as part of screening of participants with walking dysfunction into a clinical trial of exercise training in MS.

METHOD

The MSWS-12 was administered on two occasions separated by approximately 2 weeks through the telephone and then in-person (i.e., computer-based administration). Participants further completed the Patient Determined Disease Steps (PDDS) scale, timed 25-foot walk (T25FW), six-minute walk (6MW), Modified Fatigue Impact Scale (MFIS), and Multiple Sclerosis Impact Scale-29 (MSIS-29), and underwent a neurological exam for generating an expanded disability status scale (EDSS) score. The primary set of data (Full Sample) for analyses included all persons who passed the telephone screening for inclusion with MSWS-12 scores between 25 and 75 (N = 374). The secondary set of data (Truncated Sample) included only persons with MSWS-12 scores between 25 and 75 for both the telephone and computer administrations of the MSWS-12 (N = 248).

RESULTS

The results in the Full Sample indicated a difference in overall and item levels scores between the telephone and computer data collections, and the computer version had higher internal consistency and stronger unidimensionality. Nevertheless, MSWS-12 scores from both modes of administration had comparable correlations with the T25FW, 6MW, EDSS, PDDS, MFIS, and MSIS-29, but the correlation between the two MSWS-12 administrations did not approach unity. There was a systematic difference in scores between telephone and computer administrations across levels of walking dysfunction based on a Bland-Altman plot, and the difference was predicted by MFIS physical, 6MW, and EDSS scores. The comparison of results between the Full and Truncated Samples suggested that the primary analysis might have been influenced by the larger range of scores on the computer than telephone administrations of the MSWS-12.

CONCLUSION

The telephone administration of the MSWS-12 provides an efficient and cost-effective measure of walking dysfunction in persons with MS.

Criterion validity of muscle strain analyses of skeletal muscle function in patients with multiple sclerosis

BACKGROUND

Despite the wide range of existing performance measures to evaluate functional status of patients with multiple sclerosis, the heterogeneous nature of the disease hinders clinical characterization and monitoring of disease severity. Speckle tracking ultrasonography is a non-invasive technique to assess isolated muscle function by evaluating the contractile properties of muscle tissue, i.e. muscle strain. The aim of this study was to investigate whether muscle strain measured by speckle tracking ultrasonography could be a useful quantitative measure of muscle function in patients with multiple sclerosis. The criterion validity of muscle strain was compared to that of validated performance measures of upper and lower extremity function.

METHODS

This cross-sectional study used baseline data from an explorative observational cohort study (the MUST study). Participants recruited from a hospital outpatient MS clinic underwent speckle tracking ultrasonography of the biceps brachii, supraspinatus, and soleus muscles of the dominant side according to pre-defined submaximal isometric contractions. Participants also completed the Timed 25-Foot Walk Test, the Six Spot Step Test, the 2-minute walking test, the Nine-Hole Peg Test, the 12-item Multiple Sclerosis Walking Scale, and the Oxford Shoulder Score. Gaussian distribution was investigated by visual inspection of normal probability plots and the Shapiro-Wilk test. The Timed 25-Foot Walk Test and Nine-Hole Peg Test were selected as gold standards for function of the lower and upper extremities, respectively. Criterion validity was assessed using Spearman's rank-order correlation coefficient ρ (rho), comparing the muscle strain and performance measures against predefined gold standards. Differences in criterion validity were estimated using squared correlations on the Fischer's Z-scale, with non-parametric bootstrapping to obtain bias-corrected, accelerated bootstrap confidence intervals (95% BCa).

RESULTS

Criterion validity showed good to excellent correlations between the gold standard for lower extremity function and the 2-minute walking test and Six Spot Step Test, and a fair correlation to the 12-item Multiple Sclerosis Walking Scale. No significant correlation was found between the gold standard for upper extremity function and the performance measure. There were no significant correlations between the gold standards and muscle strain.

CONCLUSION

The absence of criterion validity for muscle strain alongside fair to strong criterion validity for the performance measures indicates that speckle tracking ultrasonography assessment of muscle strain is either invalid or evaluates other constructs of multiple sclerosis. Muscle strain assessed by speckle tracking ultrasonography cannot be recommended for the evaluation of treatment effects or disease progression in multiple sclerosis.

Cognitive-motor telerehabilitation in multiple sclerosis (CoMoTeMS): study protocol for a randomised controlled trial

Background

The management of cognitive impairment is an important goal in the treatment of multiple sclerosis (MS). While cognitive rehabilitation has been proven to be effective in improving cognitive performance in MS, research in the elderly indicates a higher effectiveness of combined cognitive-motor rehabilitation. Here, we present the protocol of a randomised controlled clinical trial to assess whether a combined cognitive-motor telerehabilitation programme is more effective in improving working memory than only cognitive or motor training.

Methods/design

The CoMoTeMS-trial is a two-centre, randomised, controlled and blinded clinical trial. A total of 90 patients with MS will receive 12 weeks of either a combined cognitive-motor telerehabilitation programme or only cognitive or motor training. The primary outcome is a change in the digit span backwards. Secondary outcomes are other cognitive changes (Brief International Cognitive Assessment for Multiple Sclerosis and Backward Corsi), Expanded Disability Status Scale (EDSS), 6-Min Walk Test, 25-Foot Walk Test, 9-Hole Peg Test, anxiety and depression, fatigue, quality of life, cognitive and physical activity level, electroencephalography and magnetic resonance imaging of the brain.

Discussion

We hypothesise that the improvement in digit span backwards after 12 weeks of treatment will be significantly higher in the group treated with the combined cognitive-motor telerehabilitation programme, compared to the groups receiving only cognitive and only motor training.

Trial registration

ClinicalTrials.gov NCT05355389. Registered on 2 May 2022.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06697-9.

Study Protocol: Strategies and Techniques for the Rehabilitation of Cognitive and Motor Deficits in Patients with Multiple Sclerosis

MS clinical features vary between patients. In approximately 60% of cases, cognitive deficits are associated with motor disabilities, with consequences on both walking and maintaining balance and cognitive efficiency. Multimodal programs are very infrequent for MS patients and cognitive rehabilitation is not provided by the Italian health system, which only favors access to motor rehabilitation. Dual-task studies showed how motor and cognitive skills are closely associated. Therefore, physiotherapy exercises may favor an indirect improvement in cognition. The aim of this study is to understand which rehabilitative approach may increase both cognitive and motor efficiency, avoiding the waste of time and resources. In this multi-site single-blind parallel controlled clinical trial, we will compare three rehabilitative approaches: cognitive training, motor training and combined cognitive–motor training. We also aim to evaluate: whether self-perception and objective improvement correspond; the impact of each rehabilitation program on patients’ QoL, mood and self-perception; and long-term effects. A total of 60 patients will be randomly assigned to one of the three treatments for two 45-min sessions/week for 12 weeks. All participants will undergo a complete cognitive, motor, clinical assessment together with mood, self-perception, and QoL questionnaires before, immediately after and 6 months after the training period.

Cognitive Function and Whole-Brain MRI Metrics Are Not Associated with Mobility in Older Adults with Multiple Sclerosis

Due to advances in disease-modifying medications and earlier management of comorbidities, adults with multiple sclerosis (MS) are living longer, and this coincides with the aging of the general population. One major problem among older adults with and without MS is limited mobility, a consequence of aging that often negatively affects quality of life. Identifying factors that contribute to mobility disability is needed to develop targeted rehabilitation approaches. This study examined cognitive processing speed and global brain atrophy as factors that may contribute to mobility disability in older adults with and without MS. Older adults (≥55 years) with MS (n = 31) and age- and sex-matched controls (n = 22) completed measures of mobility (Short Physical Performance Battery) and cognitive processing speed (Symbol Digit Modalities Test) and underwent an MRI to obtain whole-brain metrics (gray matter volume, white matter volume, ventricular volume) as markers of atrophy. Mobility was significantly worse in the MS group than in the control group (p = 0.004). Spearman correlations indicated that neither cognitive processing speed (MS: r_s = 0.26; Control: r_s = 0.08) nor markers of global brain atrophy (MS: r_s range = −0.30 to −0.06; Control: r_s range = −0.40 to 0.16) were significantly associated with mobility in either group. Other factors such as subcortical gray matter structures, functional connectivity, exercise/physical activity, and cardiovascular fitness should be examined as factors that may influence mobility in aging adults with and without MS.

Cognitive Processing Speed Impairment Does Not Influence the Construct Validity of Six-Spot Step Test Performance in People With Multiple Sclerosis

OBJECTIVE

There is evidence supporting the construct validity of Six-Spot Step Test (SSST) performance as a functional mobility measure in people with multiple sclerosis (MS); however, it is unknown if cognitive processing speed impairment confounds the construct validity of SSST performance in MS, as this test seemingly requires intact cognitive processing. The objective of this study was to examine the influence of cognitive processing speed impairment on the construct validity and precision of SSST performance as a functional mobility measure in MS.

METHODS

Participants (N = 213) completed the SSST, timed 25-foot walk, 6-Minute Walk Test, Timed "Up and Go" Test, Multiple Sclerosis Walking Scale-12, device-measured steps per day, and Late-Life Function and Disability Inventory, Patient-Determined Disease Steps, and the Symbol-Digit Modalities Test as a cognitive processing speed measure. The overall sample was divided into subsamples with (n = 75) and without (n = 138) cognitive processing speed impairment based on normative Symbol-Digit Modalities Test data. Correlations between SSST performance with other mobility outcomes in the overall sample and cognitive processing speed impairment subsamples were examined and compared. SSST performance was compared relative to other mobility measures for differentiating MS walking function levels in people with and without cognitive processing speed impairment.

RESULTS

SSST performance was significantly and strongly correlated with most mobility outcomes in the overall sample and cognitive processing speed impairment subsamples. The magnitudes of correlations between SSST performance with most mobility outcomes were not statistically different among subsamples. Cognitive processing speed impairment did not diminish the relative precision of SSST performance for differentiating walking function levels.

CONCLUSION

The presence of cognitive processing speed impairment is not a source of invalidity or imprecision when interpreting SSST performance as a functional mobility measure among people with MS.

IMPACT

The SSST is a high-quality endpoint for inclusion in interventions targeting mobility in MS, regardless of cognitive processing speed status. This information is critical for rehabilitation research and clinical practice given that mobility and cognitive impairment are highly prevalent, co-occurring, and disabling in MS.

Improving our understanding of the most important items of the Multiple Sclerosis Walking Scale-12 indicating mobility dysfunction: Secondary results from a RIMS multicenter study

BACKGROUND

The 12-item Multiple Sclerosis Walking Scale (MSWS-12) is currently the most widely validated, patient-reported outcome measure assessing patients' perception of the impact of multiple sclerosis (MS) on walking ability. To date, the majority of previous studies investigating the MSWS-12 have focused on the total score despite individual items being potentially informative. Therefore, our objective was to examine the associations between the individual items of the MSWS-12 and mobility and whether these associations depend on disability level.

METHODS

Participants completed the MSWS-12, Two-Minute Walk Test (2MWT), Timed 25-Foot Walk (T25FW), Timed Up and Go Test (TUG) and the Four Square Step Test (FSST). Subsequently, they were divided into two groups according to their disability level, classified as either "mildly" or "moderately-severely" disabled. The correlation between individual items of the MSWS-12 and clinical measures of mobility were separately examined by Spearman's correlation coefficients; linear regression analyses were performed for each disability group, with/without adjusting for cognition, age and gender.

RESULTS

242 people with MS (PwMS), 108 mildly and 134 moderately-severely disabled, were included. Stronger correlations between the MSWS-12 items and mobility tests were found in the mildly disabled compared to the moderately-severely disabled group. The linear regression analysis showed that in the mildly disabled, item 9 (use of support outdoors) explained 35.4%, 30.8%, and 23.7% of the variance related to the 2MWT, T25FW and TUG, respectively. As for the moderately-severely disabled, the linear regression analysis presented a model which included item 8 (use of support indoors), explaining 31.6%, 18.0%, 20.2% and 9.5% of the variance related to the 2MWT, T25FWT, TUG and FSST, respectively.

CONCLUSIONS

Items 8 and 9 of the MSWS-12 focusing on the patient's use of walking support in and outdoors, provide a robust indicator of mobility capabilities for mildly and moderately-severely disabled PwMS.

Do subcortical gray matter volumes and aerobic capacity account for cognitive-motor coupling in multiple sclerosis?

BACKGROUND

There is evidence of cognitive-motor coupling in multiple sclerosis (MS) such that the slowing of cognitive processing speed correlates with the worsening of walking speed and endurance.

OBJECTIVE

The current study first established the presence of cognitive-motor coupling and second examined the possibility that volumes of subcortical gray matter (SGM) structures and aerobic capacity might explain the coupling of cognitive and motor functions in persons with MS.

METHODS

We included data from 62 persons with clinically definite MS who underwent assessments of cognitive processing speed, walking performance, and aerobic capacity, and completed magnetic resonance imaging (MRI) within 7 days of the aforementioned assessments.

RESULTS

The strong correlations between cognitive processing speed and walking performance were attenuated in magnitude and not statistically significant when controlling for aerobic capacity alone and aerobic capacity and SGM volumes together. The associations between cognitive processing speed and walking performance remained statistically significant when controlling for SGM volumes alone.

CONCLUSION

Aerobic capacity may be an important target for neurorehabilitation-based approaches for managing co-occurring cognitive and motor dysfunction in MS.

The Intersection of Physical Function, Cognitive Performance, Aging, and Multiple Sclerosis: A Cross-sectional Comparative Study

OBJECTIVE

To examine the associations between physical function (walking speed and endurance and functional mobility) and cognitive function (information processing speed and verbal memory) in older adults with multiple sclerosis (MS) and healthy controls.

BACKGROUND

Older adults with MS have worse physical and cognitive function than older adults without MS and young and middle-aged adults with MS. To date, little is known about the associations between, or coupling of, physical and cognitive function outcomes in older adults with MS.

METHODS

We administered physical and cognitive function measures to 40 older adults with MS and 40 demographically matched healthy controls. Pearson product moment correlations were used to examine bivariate linear relationships in the overall sample and in the subsamples of (a) older adults with MS and (b) healthy controls. Linear regression analyses were used to examine the independent associations between demographic characteristics and physical and cognitive function variables in the two subsamples.

RESULTS

In the overall sample, all physical function variables were significantly correlated with cognitive function, as measured by information processing speed, and these correlations were mainly due to the subsample of older adults with MS. The linear regression analyses further indicated that information processing speed and years of education consistently explained variance in all physical function variables, beyond the influence of demographic variables, in older adults with MS.

CONCLUSIONS

Physical function and information processing speed are strongly correlated in older adults with MS. Future research should examine underlying neurobehavioral mechanisms associated with physical and cognitive function as well as behavioral strategies for jointly improving these functions in older adults with MS.

Dalfampridine benefits ambulation but not cognition in multiple sclerosis

Background:

Impaired cognition and ambulation are common in multiple sclerosis (MS). Dalfampridine is the first Food and Drug Administration (FDA)–approved medication to treat impaired ambulation in MS. Dalfampridine may benefit patients with cognitive impairment, given its effects on saltatory conduction and the association between cognitive and motor function.

Objective:

To examine the effects of dalfampridine on cognition in MS. To determine if the anticipated improved cognition is grounded in dalfampridine’s effects on ambulation.

Methods:

Adults with MS were randomized to dalfampridine ( n = 45) or placebo ( n = 16) for 12 weeks. Cognition and motor function were assessed at baseline and end-point.

Results:

T25FW and 6-minute walk (6MW) performance improved at end-point in the treatment group but not in the placebo group ( p < 0.05). Our primary outcome, performance on the Symbol Digit Modalities Test, did not improve. About 30% ( n = 12) of the dalfampridine group demonstrated ⩾20% improved ambulation and were categorized “responders.” Among “responders”, Symbol Digit Modalities test performance did not improve. However, performance on the Paced Auditory Serial Addition Test improved among “responders” ( p < 0.05).

Conclusion:

Dalfampridine benefits timed ambulation but not cognition. Some improvement among ambulation “responders” is consistent with prior reports of cognition-motor coupling in MS ( ClinicalTrials.gov #: NCT02006160).

A quantitative method for measuring the relationship between an objective endpoint and patient reported outcome measures

Patient reported outcome measures (PROMs) become increasingly important for assessing the effectiveness of a drug or medical device. In order for a PROM to be claimed in labeling, the PROM has to be valid, reliable and able to detect a change if the targeted disease status changes. One approach to assess the quality of a patient reported outcome measure (PROM) is to investigate the association between the PROM and an objective clinical endpoint measuring the status of a disease/condition. However, methods assessing the association between continuous and discrete variables are limited, especially for correlated measurements. In this paper, we propose a method to assess such association with any type of samples with or without correlation. The method involves estimating the probability revealing the status of a subject’s disease/condition (called truth thereafter) through the subject’s reported outcomes. The probability is a conditional probability revealing truth given the relative location of the subject’s objective outcome compared to the subject-specific latent threshold in the objective endpoint. A consistent estimator for the probability is derived. The operating characteristics of the consistent estimator are illustrated using simulation. Our method is applied to hypothetical clinical trial data generated for an ophthalmic device as an illustration.

Naturally occurring change in Multiple Sclerosis Walking Scale-12 scores over time in multiple sclerosis

AIM

This study examined the trajectory and pattern of naturally occurring change in perceived walking impairment over a 30-month period in relapsing-remitting multiple sclerosis (RRMS).

PATIENTS & METHODS

Two hundred and sixty-nine persons with RRMS completed the 12-item Multiple Sclerosis Walking Scale (MSWS-12) every 6 months over a 30-month period. Data were analyzed using latent growth curve modeling and latent class growth curve modeling.

RESULTS

Latent growth curve modeling demonstrated that a linear trajectory adequately described the group-level pattern of change in MSWS-12 scores over time. Latent class growth curve modeling supported a three-class model for describing the heterogeneity of changes in MSWS-12 scores over time.

CONCLUSION

Walking impairment does change over time in RRMS, and this can be described by three patterns of change trajectories that differed based on initial status of walking impairment.

Validity of the timed 25-foot walk as an ambulatory performance outcome measure for multiple sclerosis

The Multiple Sclerosis Outcome Assessments Consortium (MSOAC) includes representatives from advocacy organizations, Food and Drug Administration (FDA), European Medicines Agency (EMA), National Institute of Neurological Disorders and Stroke (NINDS), academic institutions, and industry partners along with persons living with multiple sclerosis (MS). One of the MSOAC goals is acceptance and qualification by regulators of performance outcomes that are highly reliable and valid, practical, cost-effective, and meaningful in MS. This article addresses the history, application, and psychometric properties of one such MSOAC metric of ambulation or walking namely, the timed 25-foot walk (T25FW). The T25FW has strong reliability over both brief and long periods of time in MS across a large range of disability levels. The outcome of walking speed from the T25FW has obvious real-world relevance and has correlated strongly with other measures of walking and lower extremity function. The T25FW is responsive for capturing intervention effects in pharmacological and rehabilitation trials and has an established value for capturing clinically meaningful change in ambulation. Directions for future research involve validating clinically meaningful improvements on the T25FW as well as determining whether 20% change is clinically meaningful across the disability spectrum. Researchers might further consider synchronizing accelerometers and motion sensors with the T25FW for capturing walking speed in everyday life and the patient's real environment.

Information processing speed in multiple sclerosis: Past, present, and future

BACKGROUND

Information processing speed (IPS) is a prevalent cognitive impairment in multiple sclerosis (MS).

OBJECTIVES

This review aims to summarize the methods applied to assess IPS in MS and its theoretical conceptualization. A PubMed search was performed to select articles published between 1 January 2004 and 31 December 2013, resulting in 157 articles included.

RESULTS

The majority (54%) of studies assessed IPS with heterogeneous samples (several disease courses). Studies often report controlling for presence of other neurological disorders (60.5%), age (58.6%), education (51.6%), alcohol history (47.8%), or use of steroids (39.5%). Potential confounding variables, such as recent relapses (50.3%), history of developmental disorders (19.1%), and visual problems (29.9%), were often neglected. Assessments used to study IPS were heterogeneous (ranging from simple to complex tasks) among the studies under review, with 62 different tasks used. Only 9.6% of articles defined the construct of IPS and 22.3% discussed IPS in relation to a theoretical model.

FUTURE DIRECTIONS

The challenges for the upcoming decade include clarification of the definition of IPS as well as its theoretical conceptualization and a consensus on assessment. Based on the results obtained, we propose a new theoretical model, the tri-factor model of IPS.

Thalamus volume and ambulation in multiple sclerosis: a cross-sectional study

Aim: This cross-sectional study examined if subcortical gray matter (SGM) structures accounted for differences in timed 25-foot walk (T25FW) speed between multiple sclerosis (MS) patients and controls. Methods: Subjects underwent brain MRI and completed the T25FW. Volumes of the thalamus, caudate, putamen and pallidum were calculated from 3D T1-weighted structural brain images. T2 lesion volume (T2LV) was determined by using a semiautomated edge detection contouring-thresholding technique. Results: There were differences in T25FW speed, SGM volumes and T2LV between MS and controls. T25FW speed was associated with SGM volumes and T2LV in MS and controls. Thalamic volume partially accounted for the difference in T25FW speed between the MS and controls. Conclusion: The reduction of thalamus volume is associated with compromised ambulation in MS patients.

Exercise Training and Cognitive Rehabilitation

The current review develops a rationale and framework for examining the independent and combined effects of exercise training and cognitive rehabilitation on walking and cognitive functions in persons with multiple sclerosis (MS). To do so, we first review evidence for improvements in walking and cognitive outcomes with exercise training and cognitive rehabilitation in MS. We then review evidence regarding cognitive–motor coupling and possible cross-modality transfer effects of exercise training and cognitive rehabilitation. We lastly present a macro-level framework for considering mechanisms that might explain improvements in walking and cognitive dysfunction with exercise and cognitive rehabilitation individually and combined in MS. We conclude that researchers should consider examining the effects of exercise training and cognitive rehabilitation on walking, cognition, and cognitive–motor interactions in MS and the possible physiological and central mechanisms for improving these functions.

Longitudinal changes in self-reported walking ability in multiple sclerosis

Background

Patient-reported outcomes are increasingly used to understand the clinical meaningfulness of multiple sclerosis disability and its treatments. For example, the 12-item Multiple Sclerosis Walking Scale (MSWS-12) measures the patient-reported impact of the disease on walking ability.

Objective

We studied longitudinal changes in walking ability using the MSWS-12 in a cohort of 108 patients with relapsing-remitting multiple sclerosis and moderate-to-severe disability from a single US center cohort study investigating multiple sclerosis symptoms and physical activity.

Methods

The MSWS-12 was completed every 6 months over 2 years together with self-reported measures of disease impact on daily life (Multiple Sclerosis Impact Scale) and walking disability (Patient Determined Disease Steps scale).

Results

The results revealed a high frequency of self-reported changes in walking ability at the individual level, affecting approximately 80% of patients for all four time periods. MSWS-12 scores remained stable at the group level for all four time periods. The magnitude of observed changes at the individual level was higher than the proposed minimal clinically important differences of 4 or 6 points and correlated better with Multiple Sclerosis Impact Scale physical scores than psychological scores, but little with self-reported Patient Determined Disease Steps Scale scores.

Conclusions

This novel finding of frequent fluctuations in self-reported walking ability is new and requires further investigation.

Sedentary behavior is associated with disability status and walking performance, but not cognitive function, in multiple sclerosis

Eighty-two persons with multiple sclerosis wore an accelerometer as a measure of sedentary time (min/day) and completed measures of disability status (self-reported Expanded Disability Status Scale), walking performance (timed 25-foot walk and 6-min walk), and cognitive function (symbol digit modalities test). Accelerometry-measured sedentary time was significantly correlated with disability status scores (r = 0.31, p < 0.01), 6-min walk distance (r = –0.40, p < 0.01), and timed 25-foot walk performance (r = 0.35, p < 0.01), but not cognitive function performance (r = –0.12, p = 0.29).