Development of the SMA independence scale-upper limb module (SMAIS-ULM): A novel scale for individuals with Type 2 and non-ambulant Type 3 SMA

Italian validation of the SMA independence scale-upper limb module

Spinal muscular atrophy (SMA) is a progressive disorder caused by SMN1 mutations. While therapies have changed its course, current motor scales often miss aspects. This study aimed to validate the Italian SMA Independence Scale (SMAIS-ULM) for reliability, applicability, and expansion across diverse SMA phenotypes. Patients with genetically confirmed 5qSMA were recruited from 12 Italian centers. Analyses included Intraclass Correlation Coefficients (ICCs) for test-retest reliability, the Kruskal-Wallis for group comparisons, and the Spearman correlations with functional measures. Ceiling/floor effects were defined as ≥ 85% of a group reaching the maximum or minimum score. The study analyzed 472 completed questionnaires: 263 from caregivers (mean age 26.4 ± 17.6; 29 SMA I, 123 SMA II, 104 SMA III, 7 presymptomatic) and 209 from patients (mean age 33.1 ± 16.4; 3 SMA I, 101 SMA II, 104 SMA III; 1 SMA IV), including 195 matched caregiver-patient pairs. ICC was conducted in 29 caregivers and 31 patients; values ranged from 0.97 to 1.00. SMAIS-ULM scores differed by SMA type, with SMA III/presymptomatic subjects scoring higher than SMA I/II (p < 0.001) and walkers scoring higher than sitters/non-sitters (p < 0.001). Floor effects were found in 18.9% of non-sitters and 50% of walkers, with comparable patterns in patient responses. Strong correlations with functional measures were found, with no significant differences between caregiver and patient reports. Conclusion: The findings confirm the reliability and validity of the SMAIS-ULM as an effective tool for measuring functional independence in individuals with SMA, both from the caregiver and patient perspectives.

SMA Community Priorities for Future Drug Therapies: Cross-Sectional Survey Findings Representing 410 Adults with SMA

INTRODUCTION

Despite advances in the therapeutic landscape for spinal muscular atrophy (SMA), unmet needs for those with this condition persist. This study seeks to characterize unmet needs that adults with SMA hope future therapies will address and explores associations between reported needs and health status and demographic characteristics.

METHODS

Close-ended questions from 2021 to 2023 Cure SMA Community Update Survey data were used to assess the importance of needs related to muscle and motor function, lung function and bulbar function, and general functioning. Data was stratified by SMA type and mobility status, and Fisher's exact tests were used to assess for statistically significant differences based on these characteristics. Variations in reported needs were further explored with regressions controlling for sex, education, maximum mobility, and drug treatment status.

RESULTS

The sample included 410 adults who answered questions on unmet needs. Most had type 2 or type 3 SMA (48% and 45%, respectively). Gaining muscle strength was the most frequently reported unmet need, and followed by improving daily functioning, achieving new motor function, and stabilizing motor function. Stratifications and regressions identified statistically significant differences in treatment needs based on health status and demographic characteristics (p < 0.05). Most notably, people with more severe types of SMA and lower mobility were more likely to report items related to lung function and bulbar function as important.

CONCLUSION

This research highlights treatment priorities for adults with SMA.

Thinking outside the box: A re-evaluation of Canadian recommended outcome measures in adult spinal muscular atrophy - report of a national consensus workshop

BackgroundDisease-modifying therapies for persons with spinal muscular atrophy (SMA) has led to greater need and demand for relevant outcomes assessments. Such tools help monitor disease progression, assess treatment response, and inform clinical management. Canadian SMA clinicians participated in a Delphi process to achieve a 2021 national consensus on recommended outcomes, recognizing future reassessment would be essential given the evolving field and gaps in patient-reported and bulbar measures.ObjectiveDerive updated Canadian consensus of recommended outcome measures for adults with SMA.MethodsA national consensus workshop was held with SMA clinicians, patient/family representatives, research leaders, national registry and advocacy organizations. Clinics and registry experience and data were presented and discussed, utility of current and additional outcomes reviewed. Long and short lists of measures were generated, with voting to derive consensus.ResultsPractical implementation, value of data, and relevance to persons with SMA were key considerations. Consensus was achieved to 'think outside the box', recognizing a spectrum of function and need to choose the right outcome measure for the right patient at the right time. Measures with greater acceptance for adults were selected, and bulbar measures introduced. Eight outcome measures are recommended; 4 motor, 2 respiratory and 2 patient reported domains, with use based on the individuals level of function. The Revised Upper Limb Module was deemed to have broadest applicability except in the strongest and weakest adults. Additional measures are included as optional and exploratory.ConclusionsEmploying measures meaningful for clinicians, researchers, and persons living with SMA is essential to ensuring quality data collection and an engaged patient-centred clinical team. Clinicians should select measures based on the person's functional ability and goals. Building a national community of practice to support clinical and research practice, including standardized outcome measure training, will be a key next step in dissemination and advocacy.

Serum creatinine to cystatin C ratio as monitoring biomarker in Chinese adult spinal muscular atrophy: a prospective cohort study

BACKGROUND

The creatinine to cystatin C ratio (CCR) can be used as a biomarker of muscle mass and strength, but no studies have evaluated whether it can be used as a biomarker to monitor the efficacy of treatment with nusinersen in Chinese adults with 5q-associated spinal muscular atrophy (SMA).

METHODS

In this prospective observational study, 28 adult SMA patients were followed for 18 months. Data on motor function and daily activities were collected using the Hammersmith Functional Motor Scale Expanded (HFMSE), Revised Upper Limb Module (RULM), 6-Minute Walking Test (6WMT), and Barthel Index (BI). Serum levels of creatinine (Cr), creatine kinase (CK), and CCR were measured. Spearman correlation and linear mixed models analyzed the relationships between functional scores and laboratory indicators.

RESULTS

HFMSE scores showed significant improvement at Visit 5 (V5) [+ 1.04 points, p = 0.016), V6 (+ 1.61, p = 0.012), V7 (+ 1.93, p < 0.001), and V8 (+ 1.89, p < 0.001)], while RULM scores improved significantly at V5 (+ 2.00 points, p = 0.024), V7 (+ 2.00, p = 0.032), and V8 (+ 2.00, p < 0.001). The BI also exhibited significant improvement at V7 (+ 5.00, p < 0.001) and V8 (+ 2.50, p < 0.001). The 6MWT did not show significant improvement (p > 0.05). Serum CCR levels were significantly higher than baseline at V5 (+ 4.35 points, p < 0.001), V7 (+ 5.12, p < 0.001), and V8 (+ 6.59, p < 0.001). Cr levels were significantly higher than baseline at V5 (+ 2.39 points, p < 0.001) and V7 (+ 0.90, p < 0.001), while log10 CK levels remained unchanged (p > 0.05). Spearman correlation analysis revealed CCR showed the strongest correlation with functional scores, followed by Cr and log10 CK. Further linear mixed-effect model indicated that after adjusting for covariates, only CCR showed a dynamic positive correlation with HFMSE scores (β = 0.280; 95% CI 0.023-0.537, p = 0.033), while other serum indicators had no correlation with functional scores.

CONCLUSION

Long-term use of nusinersen effectively improves motor function and quality of life in adult SMA patients, and CCR may be a better indicator to reflect changes in motor function during treatment compared to other blood biomarkers.

Impact of Nusinersen Treatment on the Independence and Mental Health of School-Aged Patients With Spinal Muscular Atrophy

BACKGROUND

Emerging disease-modifying therapies for spinal muscular atrophy (SMA) have altered patients' mental health and daily functioning. This longitudinal study evaluated nusinersen's effects on independence and mental health in school-age SMA patients.

METHODS

Thirty-one SMA type 2/3 patients from a pediatric hospital were assessed using the SMA Independence Scale-Upper Limb Module (SMAIS-ULM), Screen for Child Anxiety-Related Emotional Disorders (SCARED), and Depression Self-Rating Scale for Children (DSRSC). Motor function was measured via Hammersmith Functional Motor Scale-Expanded (HFMSE) and Revised Upper Limb Module (RULM), with correlations analyzed.

RESULTS

Median treatment initiation age was 9.19 (8.73-11.90) years. After 14 months, SMAIS-ULM scores improved significantly (P < 0.01), while anxiety/depression rates declined (P < 0.01). Higher HFMSE scores correlated with better independence (P < 0.01) and reduced anxiety/depression (P < 0.01). Similarly, higher RULM scores predicted greater independence (P < 0.01) and lower anxiety (P < 0.05).

CONCLUSIONS

Nusinersen therapy enhances independence and mental health in school-age SMA patients, supported by patient-reported outcomes. These findings underscore its multifaceted therapeutic benefits.

Assessing disease progression in spinal muscular atrophy, current gaps, and opportunities: a narrative review

Spinal Muscular Atrophy is a genetic disorder causing muscle atrophy and progressive weakness. People living with the condition can have a significant heterogenous phenotype ranging from arrest of motor development to mild impairment. Assessing disease severity has been done using a range of outcome measures that can be classified by body structure or function, by activities or by participation. Functional outocome measures can be generic measures, used to compare individuals or populations against general norms, or disease-specific measures designed to fit disease characteristics. Outcome measures assessing participation are primarily used to capture patients' perceptions of health-related quality of life, daily activity abilities, caregiver burden, and the impact of physical symptoms like fatigue or pain. When assessing disease progression, often the focus on functional abilities has served as an overall indicator of change. With the appearance of disease modifying therapies and the need to evaluate the impact that they had in the course of the disease, new requirements for the existing assessments measure had appeared. The current available toolkit is able to capture a significant spectrum of both, natural history and effect of new treatments but the increased survival, changes in fatigue, bulbar function and others will benefit from further assessment.

Longitudinal Efficacy of Nusinersen Treatment on Health-Related Quality of Life and Independence in Children With Later-Onset Spinal Muscular Atrophy

INTRODUCTION/AIMS

The rising use of disease-modifying therapy is progressively impacting the health-related quality of life (HRQoL) of patients with spinal muscular atrophy (SMA) in their daily lives. This study aimed to evaluate the changes in HRQoL and independence in children with later-onset SMA receiving longitudinal treatment with nusinersen.

METHODS

Forty-nine pediatric patients with later-onset SMA (symptom onset after 6 months of age) and their caregivers were enrolled. The HRQoL of patients evaluated by the proxy-reported Pediatric Quality of Life Inventory 3.0 Neuromuscular Module (PedsQL NMM) and the independence level determined by the SMA Independence Scale-Upper Limb Module (SMAIS-ULM) were assessed. Caregiver HRQoL was assessed using the Pediatric Quality of Life Inventory Family Impact Module (PedsQL FIM). Motor function was recorded using the Hammersmith Functional Motor Scale Expanded (HFMSE) and the Revised Upper Limb Module (RULM), with subsequent analysis of the correlation between motor function, HRQoL, and independence scores.

RESULTS

A significant difference was observed across all domains of the proxy-reported PedsQL NMM and in the independence assessment over the 18-month follow-up period (p < 0.001). A positive correlation was identified between RULM and total PedsQL NMM scores (Pearson-r = 0.539, p < 0.001), as well as SMAIS-ULM scores (Spearman-rho = 0.507, p < 0.001). Scores in all modules of the PedsQL FIM improved over time (p < 0.001).

DISCUSSION

This study demonstrates the longitudinal effects of nusinersen treatment on multifaceted aspects of SMA patients, as captured by patient-reported outcome measures (PROMs). The inclusion of PROMs should be considered as part of the SMA multidisciplinary assessment.

An exploratory qualitative assessment of patient and clinician perspectives on patient-reported outcome measures and disease-modifying therapies in adults with spinal muscular atrophy

OBJECTIVE

To understand patient, caregiver, and clinician perspectives on patient-reported outcome measures, critical functional domains, and disease-modifying therapies in adult spinal muscular atrophy.

DESIGN

An exploratory qualitative single-site study.

PATIENTS

Ten adults with spinal muscular atrophy and two clinicians participated in semi-structured interviews.

METHODS

Semi-structured interviews were conducted virtually or in person with participants after they completed outcome measures at a routine clinic visit. Two researchers analysed transcripts concurrently using a thematic approach to determine themes.

RESULTS

Ten themes were identified among partici-pants. Patient-reported outcome measure preference varied between functional groups and was under-responsive, although it captured meaningful data. Motor stability was most frequently expected with disease-modifying therapy, but participants also reported improved fatigue and respiratory status.

CONCLUSION

After considering patient goals, functional status, and preferences, patient-reported outcome measures represent a valuable adjunct to standard clinical and research tools. Optimal selection of patient-reported outcome measures requires careful consideration of multiple patient factors. Collaborative development of modified patient-reported outcome measures may yield a responsive, meaningful, and acceptable tool that can be used across a broad functional spectrum.

Taldefgrobep Alfa and the Phase 3 RESILIENT Trial in Spinal Muscular Atrophy

Spinal muscular atrophy (SMA) is a rare, genetic neurodegenerative disorder caused by insufficient production of survival motor neuron (SMN) protein. Diminished SMN protein levels lead to motor neuron loss, causing muscle atrophy and weakness that impairs daily functioning and reduces quality of life. SMN upregulators offer clinical improvements and increased survival in SMA patients, although significant unmet needs remain. Myostatin, a TGF-β superfamily signaling molecule that binds to the activin II receptor, negatively regulates muscle growth; myostatin inhibition is a promising therapeutic strategy for enhancing muscle. Combining myostatin inhibition with SMN upregulation, a comprehensive therapeutic strategy targeting the whole motor unit, offers promise in SMA. Taldefgrobep alfa is a novel, fully human recombinant protein that selectively binds to myostatin and competitively inhibits other ligands that signal through the activin II receptor. Given a robust scientific and clinical rationale and the favorable safety profile of taldefgrobep in patients with neuromuscular disease, the RESILIENT phase 3, randomized, placebo-controlled trial is investigating taldefgrobep as an adjunct to SMN upregulators in SMA (NCT05337553). This manuscript reviews the role of myostatin in muscle, explores the preclinical and clinical development of taldefgrobep and introduces the phase 3 RESILIENT trial of taldefgrobep in SMA.

Measurement properties of the EQ-5D-Y-3L, PedsQL 4.0, and PROMIS-25 Profile v2.0 in pediatric patients with spinal muscular atrophy

OBJECTIVE

The objective of this study was to examine the psychometric properties of the EQ-5D-Y-3 L, Patient Reported Outcomes Measurement System 25-item version profile v2.0 (PROMIS-25), and Pediatric Quality of Life Inventory™ version 4.0 Generic Core Scale (PedsQL 4.0) in Chinese pediatric patients with spinal muscular atrophy (SMA).

METHODS

The data used in this study were obtained via a web-based cross-sectional survey. Parents of pediatric patients with SMA completed the proxy-reported EQ-5D-Y-3 L, PedsQL 4.0, and PROMIS-25 measures. Information about socioeconomic and health status was also obtained. The ceiling and floor effects, factorial structure, convergent validity, and known-group validity of the three measures were assessed.

RESULTS

Three hundred and sixty-three parents of children aged from 5 to 12 completed the questionnaires. Strong floor effects were observed for the physical function components of the PROMIS-25 (41.3%) and PedsQL 4.0 (67.8%). For EQ-5D-Y-3 L, 84.6% of the respondents reported having "a lot of" problems with the dimensions "walking" and "looking after myself." Minimal ceiling or floor effects were observed for the EQ-5D-Y-3 L index value. The confirmatory factor analysis supported a six-factor structure for the PROMIS-25, but did not support a four-factor structure for the PedsQL 4.0. All hypothesized correlations of the dimensions among the three measures were confirmed, with coefficients ranging from 0.28 to 0.68. Analysis of variance showed that EQ-5D-Y-3 L demonstrated better known-group validity than the other two measures in 14 out of 16 comparisons.

CONCLUSIONS

The EQ-5D-Y-3 L showed better discriminant power than the other two measures. The physical health dimensions of all three measures showed the significant floor effects. These findings provide valuable insights into the effectiveness of these measures at capturing and quantifying the impact of SMA on patients' health-related quality of life.

Design and Validation of a Clinical Outcome Measure for Adolescents and Adult Patients with Spinal Muscular Atrophy: SMA Life Study Protocol

INTRODUCTION

The objective of this study is to develop a clinical tool for the evaluation and follow-up of adolescent and adult patients with 5q spinal muscular atrophy (SMA) and to design its validation.

METHODS

This prospective, non-interventional study will be carried out at five centres in Spain and will include patients aged 16 years or older with a confirmed diagnosis of 5q SMA (biallelic mutation of the survival motor neuron 1 [SMN1] gene). A panel of experts made up of neurologists, physiatrists and Spanish patients' association (FundAME), participated in the design of the clinical tool. Physicians will administer the tool at three time points (baseline, 12 months and 24 months). Additionally, data from other questionnaires and scales will be collected. Once recruitment is achieved, an interim statistical analysis will be performed to assess its psychometric properties by applying Rasch analysis and classical statistical tests.

RESULTS

The tool will consist of up to 53 items to assess functional status from a clinical perspective in seven key dimensions (bulbar, respiratory, axial, lower, upper, fatigability and other symptoms), which will be collected together with objective clinical measures (body mass index, forced vital capacity, pinch strength and 6-minute walk test).

CONCLUSIONS

The validation of this tool will facilitate the clinical evaluation of adult and adolescent patients with SMA and the quantification of their response to new treatments in both clinical practice and research.

Measurement properties of the EQ-5D-5L and PROPr in patients with spinal muscular atrophy

OBJECTIVES

Spinal muscular atrophy (SMA) is a rare monogenic neuromuscular disorder caused by loss of function mutations. Measuring health-related quality of life to support economic evaluations in this population is encouraged. However, empirical evidence on the performance of preference-based measures (PBMs) in individuals with SMA is limited. This study aimed to assess the psychometric properties of the EQ-5D-5L and the Patient-Reported Outcomes Measure Information System Preference measure (PROPr) in individuals with SMA.

METHODS

The data used in this study were obtained via a web-based, cross-sectional survey. All participants completed the self-reporting EQ-5D-5L and PROMIS-29 questionnaires. Information about their socioeconomic and health status was also obtained. Ceiling and floor effects, convergent and divergent validity, known-group validity, and the agreement between the two measures were assessed.

RESULTS

Strong ceiling and floor effects were observed for four dimensions of the EQ-5D-5L and three subscales, including pain intensity, pain interference, and physical function, of the PROMIS-29. All hypothesized associations between EQ-5D-5L/PROMIS-29 and other neuromuscular questions were confirmed, supporting good convergent validity. Moreover, both EQ-5D-5L and PROPr scores differentiated between impaired functional groups, demonstrating good discriminative ability. Poor agreement between the EQ-5D-5L and PROPr utility scores was observed.

CONCLUSIONS

The EQ-5D-5L and PROPr both appear to be valid PBMs for individuals with SMA. However, PROPr yielded considerably lower utility scores than EQ-5D-5L and their agreement was poor. Therefore, these two PBMs may not be used interchangeably in economic evaluations of SMA-related interventions.

Digital measures of respiratory and upper limb function in spinal muscular atrophy: design, feasibility, reliability, and preliminary validity of a smartphone sensor-based assessment suite

Spinal muscular atrophy (SMA) is characterized by progressive muscle weakness and paralysis. Motor function is monitored in the clinical setting using assessments including the 32-item Motor Function Measure (MFM-32), but changes in disease severity between clinical visits may be missed. Digital health technologies may assist evaluation of disease severity by bridging gaps between clinical visits. We developed a smartphone sensor-based assessment suite, comprising nine tasks, to assess motor and muscle function in people with SMA. We used data from the risdiplam phase 2 JEWELFISH trial to assess the test-retest reliability and convergent validity of each task. In the first 6 weeks, 116 eligible participants completed assessments on a median of 6.3 days per week. Eight of the nine tasks demonstrated good or excellent test-retest reliability (intraclass correlation coefficients >0.75 and >0.9, respectively). Seven tasks showed a significant association (P < 0.05) with related clinical measures of motor function (individual items from the MFM-32 or Revised Upper Limb Module scales) and seven showed significant association (P < 0.05) with disease severity measured using the MFM-32 total score. This cross-sectional study supports the feasibility, reliability, and validity of using smartphone-based digital assessments to measure function in people living with SMA.

Safety and Efficacy of Nusinersen and Risdiplam for Spinal Muscular Atrophy: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

OBJECTIVE

We performed a systematic review and meta-analysis of the efficacy and safety of nusinersen and risdiplam in the treatment of spinal muscular disease (SMA).

METHODS

We screened the literature published in Pubmed, Web of Science, Embase, and Cochrane before July 2023 to conduct randomized controlled trials to test the treatment of SMA patients with nusinersen and risdiplam. The data were analyzed using Review Manager 5.4 software and Stata version 15.0 software.

RESULTS

A total of six randomized controlled trials were included, involving 728 SMA patients, to synthesize evidence. It is reported that nusinersen treatment was beneficial for increasing the score of the Hammersmith Functional Motor Scale-Expanded (HFMSE) (WMD: 4.90; 95% CI: 3.17, 6.63; p < 0.00001), Revised Upper Limb Module (RULM) (WMD: 3.70; 95% CI: 3.30, 4.10; p < 0.00001), and Hammersmith Infant Neurological Evaluation Section 2 (HINE-2) (WMD: 5.21; 95% CI: 4.83, 5.60; p < 0.00001). In addition, the risdiplam treatment group also showed statistically significant improvements in the HFMSE score (WMD:0.87; 95% CI: 0.05, 1.68; p = 0.04), the 32-item Motor Function Measure (MFM32) (WMD:1.48; 95% CI: 0.58, 2.38; p = 0.001), and (WMD: 1.29; 95% CI: 0.57, 2.01; p = 0.0005). Nusinersen and risdiplam did not cause a statistically significant increase in the RULM score for adverse events (OR: 0.93; 95% CI: 0.51, 1.7; p = 0.82) and for severe adverse events (OR: 0.77; 95% CI: 0.47, 1.27; p = 0.31).

CONCLUSION

Our analysis found that nusinersen and risdiplam treatment showed clinically meaningful improvement in motor function and a similar incidence rate of adverse events compared with the placebo. Further research should be carried out to provide a direct comparison between the two drugs in terms of safety and efficacy.

Two-year efficacy and safety of risdiplam in patients with type 2 or non-ambulant type 3 spinal muscular atrophy (SMA)

Risdiplam is an oral, survival of motor neuron 2 (SMN2) pre-mRNA splicing modifier approved for the treatment of spinal muscular atrophy (SMA). SUNFISH (NCT02908685) Part 2, a Phase 3, randomized, double-blind, placebo-controlled study, investigated the efficacy and safety of risdiplam in type 2 and non‑ambulant type 3 SMA. The primary endpoint was met: a significantly greater change from baseline in 32-item Motor Function Measure (MFM32) total score was observed with risdiplam compared with placebo at month 12. After 12 months, all participants received risdiplam while preserving initial treatment blinding. We report 24-month efficacy and safety results in this population. Month 24 exploratory endpoints included change from baseline in MFM32 and safety. MFM‑derived results were compared with an external comparator. At month 24 of risdiplam treatment, 32% of patients demonstrated improvement (a change of ≥ 3) from baseline in MFM32 total score; 58% showed stabilization (a change of ≥ 0). Compared with an external comparator, a treatment difference of 3.12 (95% confidence interval [CI] 1.67-4.57) in favor of risdiplam was observed in MFM-derived scores. Overall, gains in motor function at month 12 were maintained or improved upon at month 24. In patients initially receiving placebo, MFM32 remained stable compared with baseline (0.31 [95% CI - 0.65 to 1.28]) after 12 months of risdiplam; 16% of patients improved their score and 59% exhibited stabilization. The safety profile after 24 months was consistent with that observed after 12 months. Risdiplam over 24 months resulted in further improvement or stabilization in motor function, confirming the benefit of longer-term treatment.

Validation of a Set of Instruments to Assess Patient- and Caregiver-Oriented Measurements in Spinal Muscular Atrophy: Results of the SMA-TOOL Study

INTRODUCTION

Outcome measures traditionally used in spinal muscular atrophy (SMA) clinical trials are inadequate to assess the full range of disease severity. The aim of this study was to assess the psychometric properties of a set of existing questionnaires and new items, gathering information on the impact of SMA from the patient and caregiver perspectives.

METHODS

This was a multicenter, prospective, noninterventional study including patients with a confirmed diagnosis of 5q-autosomal-recessive SMA aged 8 years and above, or their parents (if aged between 2 and 8 years). The set of outcome measurements included the SMA Independence Scale (SMAIS) patient and caregiver versions, the Neuro-QoL Fatigue Computer Adaptive Test (CAT), the Neuro-QoL Pain Short Form-Pediatric Pain, the PROMIS adult Pain Interference CAT, and new items developed by Fundación Atrofia Muscular España: perceived fatigability, breathing and voice, sleep and rest, and vulnerability. Reliability, construct validity, discriminant validity, and sensitivity to change (4 months from baseline) were measured.

RESULTS

A total of 113 patients were included (59.3% 2-17 years old, 59.3% male, and 50.4% with SMA type II). Patients required moderate assistance [mean patient and caregiver SMAIS (SD) scores were 31.1 (12.8) and 7.6 (11.1), respectively]. Perceived fatigability was the most impacted domain, followed by vulnerability. Cronbach's alpha coefficient for perceived fatigability, breathing and voice, and vulnerability total scores were 0.92, 0.88, and 0.85, respectively. The exploratory factor analysis identified the main factors considered in the design, except in the sleep and rest domain. All questionnaires were able to discriminate between the Clinical Global Impression-Severity scores and SMA types. Sensitivity to change was only found for the SMAIS caregiver version and vulnerability items.

CONCLUSIONS

This set of outcome measures showed adequate reliability, construct validity, and discriminant validity and may constitute a valuable option to measure symptom severity in patients with SMA.

A Mixed-method Approach to Develop an Ambulatory Module of the SMA Independence Scale

BACKGROUND

Limited qualitative data exist on the symptoms and impacts of spinal muscular atrophy (SMA) experienced by ambulant individuals. An ambulant module of the SMA Independence Scale (SMAIS) was developed to quantify the assistance required to perform everyday mobility-related activities.

OBJECTIVE

The objective of this study was to develop a patient-centered module that provides key insights into what constitutes independence for ambulant and near-ambulant individuals with SMA.

METHODS

A stepwise, mixed-method approach was used. Semi-structured interviews were conducted in three waves with individuals with SMA and caregivers of children with SMA who were ambulant or near-ambulant (can walk ≥5 steps with support). Wave 1 interviews (n = 20) focused on concept elicitation. Wave 2 and 3 interviews (n = 15, both) involved completion and cognitive debriefing of items generated based on Wave 1 interviews. Therapeutic area experts were consulted throughout all key steps of the study. In particular, feedback was provided for item refinement and response option decisions. A macro-level preliminary, exploratory analysis, using Rasch Measurement Theory (RMT), provided insight on measurement properties.

RESULTS

Wave 1 resulted in 42 mobility and 11 instrumental activity of daily living (iADL) items. During Wave 2, participants defined independence as completing a task with supportive aids but without help from another person, leading to item refinement and modifications to the response scale. Lack of conceptual relevance and ceiling effects led to the removal of all iADL items after Wave 2, and 41 mobility items were tested in Wave 3. Final exploratory RMT and item refinement to reduce overlap led to a 27-item set related to mobility tasks.

CONCLUSIONS

Our study provides preliminary support for using the 27-item SMAIS-Ambulatory Module for ambulant or near-ambulant individuals with SMA. Larger-scale analyses to further assess the psychometric properties of the scale are warranted.

Risdiplam: an investigational motor neuron-2 (SMN-2) splicing modifier for spinal muscular atrophy (SMA)

INTRODUCTION

Spinal muscular atrophy (SMA) is a rare autosomal recessive neuromuscular disease which is characterized by muscle atrophy and early death in most patients. Risdiplam is the third overall and first oral drug approved for SMA with disease-modifying potential. Risdiplam acts as a survival motor neuron 2 (SMN2) pre-mRNA splicing modifier with satisfactory safety and efficacy profile. This review aims to critically appraise the place of risdiplam in the map of SMA therapeutics.

AREAS COVERED

This review gives an overview of the current market for SMA and presents the mechanism of action and the pharmacological properties of risdiplam. It also outlines the development of risdiplam from early preclinical stages through to the most recently published results from phase 2/3 clinical trials. Risdiplam has proved its efficacy in pivotal trials for SMA Types 1, 2, and 3 with a satisfactory safety profile.

EXPERT OPINION

In the absence of comparative data with the other two approved drugs, the role of risdiplam in the treatment algorithm of affected individuals is examined in three different patient populations based on the age and diagnosis method (newborn screening or clinical, symptom-driven diagnosis). Long-term data and real-world data will play a fundamental role in its future.

A Patient-Centered Evaluation of Meaningful Change on the 32-Item Motor Function Measure in Spinal Muscular Atrophy Using Qualitative and Quantitative Data

The 32-item Motor Function Measure (MFM32) is an assessment of motor function used to evaluate fine and gross motor ability in patients with neuromuscular disorders, including spinal muscular atrophy (SMA). Reliability and validity of the MFM32 have been documented in individuals with SMA. Through semi-structured qualitative interviews (N = 40) and an online survey in eight countries (N = 217) with individuals with Types 2 and 3 SMA aged 2–59 years old and caregivers, the meaning of changes on a patient-friendly version of the MFM32 was explored. In an independent analysis of clinical trial data, anchor- and distribution-based analyses were conducted in a sample of individuals with Type 2 and non-ambulant Type 3 SMA to estimate patient-centered quantitative MFM32 meaningful change thresholds. The results from this study demonstrate that, based on patient and caregiver insights, maintaining functional ability as assessed by a patient-friendly version of the MFM32 is an important outcome. Quantitative analyses using multiple anchors (median age range of 5–8 years old across anchor groups) indicated that an ~3-point improvement in MFM32 total score represents meaningful change at the individual patient level. Overall, the qualitative and quantitative findings from this study support the importance of examining a range of meaningful change thresholds on the MFM32 including ≥0 points change reflecting stabilization or improvement and ≥3 points change reflecting a higher threshold of improvement. Future research is needed to explore quantitative differences in meaningful change on the MFM32 based on age and functional subgroups.