The Performance of the Upper Limb scores correlate with pulmonary function test measures and Egen Klassifikation scores in Duchenne muscular dystrophy

Draft Guidance for Industry Duchenne Muscular Dystrophy, Becker Muscular Dystrophy, and Related Dystrophinopathies - Developing Potential Treatments for the Entire Spectrum of Disease

Background

Duchenne muscular dystrophy (DMD) and related dystrophinopathies are neuromuscular conditions with great unmet medical needs that require the development of effective medical treatments.

Objective

To aid sponsors in clinical development of drugs and therapeutic biological products for treating DMD across the disease spectrum by integrating advancements, patient registries, natural history studies, and more into a comprehensive guidance.

Methods

This guidance emerged from collaboration between the FDA, the Duchenne community, and industry stakeholders. It entailed a structured approach, involving multiple committees and boards. From its inception in 2014, the guidance underwent revisions incorporating insights from gene therapy studies, cardiac function research, and innovative clinical trial designs.

Results

The guidance provides a deeper understanding of DMD and its variants, focusing on patient engagement, diagnostic criteria, natural history, biomarkers, and clinical trials. It underscores patient-focused drug development, the significance of dystrophin as a biomarker, and the pivotal role of magnetic resonance imaging in assessing disease progression. Additionally, the guidance addresses cardiomyopathy's prominence in DMD and the burgeoning field of gene therapy.

Conclusions

The updated guidance offers a comprehensive understanding of DMD, emphasizing patient-centric approaches, innovative trial designs, and the importance of biomarkers. The focus on cardiomyopathy and gene therapy signifies the evolving realm of DMD research. It acts as a crucial roadmap for sponsors, potentially leading to improved treatments for DMD.

Factors Associated with Respiratory Health and Function in Duchenne Muscular Dystrophy: A Systematic Review and Evidence Grading

BACKGROUND

Despite advances in the medical management of the disease, respiratory involvement remains a significant source of morbidity and mortality in children and adults with Duchenne muscular dystrophy (DMD).

OBJECTIVE

The objective of this systematic literature review was to synthesize and grade published evidence of factors associated with respiratory health and function in DMD.

METHODS

We searched MEDLINE, Embase, and the Cochrane Library for records of studies published from January 1, 2000 (to ensure relevance to current care practices), up until and including December 31, 2022, reporting evidence of prognostic indicators and predictors of disease progression in DMD. The quality of evidence (i.e., very low to high) was assessed using the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) framework.

RESULTS

The bibliographic search strategy resulted in the inclusion of 29 articles. In total, evidence of 10 factors associated with respiratory health and function in patients with DMD was identified: glucocorticoid exposure (high- to very low-quality evidence), DMD mutations (low-quality evidence), DMD genetic modifiers (low-quality evidence), other pharmacological interventions (i.e., ataluren, eteplirsen, idebenone, and tamoxifen) (moderate- to very low-quality evidence), body mass index and weight (low-quality evidence), and functional ability (low-quality evidence).

CONCLUSIONS

In conclusion, we identified a total of 10 factors associated with respiratory health in function in DMD, encompassing both pharmacological therapies, genetic mutations and modifiers, and patient clinical characteristics. Yet, more research is needed to further delineate sources of respiratory heterogeneity, in particular the genotype-phenotype association and the impact of novel DMD therapies in a real-world setting. Our synthesis and grading should be helpful to inform clinical practice and future research of this heavily burdened patient population.

Do handgrip strength and dexterity predict respiratory function in neuromuscular disease?

BACKGROUND

Neuromuscular diseases are acquired or inherited diseases that affect the function of the muscles in our body, including respiratory muscles.

OBJECTIVE

We aimed to discover more cost-effective and practical tools to predict respiratory function status, which causes serious problems with patients with neuromuscular disease.

METHODS

The Vignos and Brooke Upper Extremity Functional Scales were used to evaluate functional status for patient recruitment. The handgrip strength and dexterity of patients were measured using a dynamometer and nine-hole peg test. Respiratory function parameters: forced vital capacity, forced expiratory volume in one second, and peak expiratory flow were evaluated using spirometry.

RESULTS

The mean age of the 30 patients was 11.5 ± 3.79 years old. Significant relationships were found between nine-hole-peg-test scores and respiratory function parameters on both sides. Significant correlations were found between both handgrip strength and respiratory function parameters (p < 0.05). In the linear regression analysis, it was seen that the forced expiratory volume in 1 second, and peak expiratory flow values could be explained in different percentages (p < 0.05).

CONCLUSIONS

Handgrip strength and dexterity measurements can be used as indicators for estimating respiratory function parameters in terms of cost and accessibility, although it is known that they will not replace respiratory function tests.

The Association between the Respiratory System and Upper Limb Strength in Males with Duchenne Muscular Dystrophy: A New Field for Intervention?

Progressive, irreversible muscle weakness is the leading symptom of Duchenne muscular dystrophy (DMD), often resulting in death from respiratory muscle failure. Little is known about the relationship between the functioning of the respiratory system and the hand grip-a function which remains long preserved. This study aimed to investigate the interdependence between muscle strength and the function of both hand grip and the respiratory system in patients with DMD.

MATERIALS AND METHOD

The study included cohort patients, aged 6-17, with DMD, recruited from the Rare Disease Centre, Gdansk, Poland. Clinical status (Vignos scale, Brook scale), pulmonary function (respiratory muscle strength-MIP, MEP); spirometry (FEV1; FVC), as well as upper limb function (performance of the upper limb-PUL 2.0) and hand grip strength (HGS) (hand-held dynamometer) were evaluated in all participants.

RESULTS

Finally, 53 boys (mean age 11.41 ± 3.70 years, 25 non-ambulant) were included. Each of the participants presented a lower %pv of MIP (48.11 ± 27), MEP (38.11 ± 22), PUL (75.64 ± 27), and HGS (33.28 ± 18). There were differences between the ambulatory and non-ambulatory groups in values of MIP, MEP, FVC, PUL, HGS (p < 0.001 for all), and FEV1 (p < 0.013). There were correlations between PUL, HGS, and MIP (R = 0.56; R = 0.61, p < 0.001 both), MEP (R = 0.59; R = 0.62, p < 0.001), FVC (R = 0.77; R = 0.77, p < 0.001), and FEV1 (R = 0.77; R = 0.79; p < 0.001). These correlations were found for all participants, but non-ambulatory patients presented stronger relationships.

CONCLUSIONS

1. The pulmonary and upper limb functions were within the normal range in ambulatory and low in non-ambulatory patients with DMD, but the muscle strength of both systems was low, regardless of the stage of the disease. 2. There seems to be an interdependence between the respiratory system and upper limb strength in terms of muscle strength and function in DMD patients, which is stronger in non-ambulatory patients. This may be the basis for the creation of a new personalized plan in rehabilitation-the simultaneous rehabilitation of the respiratory and upper limb muscles. Further studies on this theory should be conducted.

Assessing the Relationship of Patient Reported Outcome Measures With Functional Status in Dysferlinopathy: A Rasch Analysis Approach

Dysferlinopathy is a muscular dystrophy with a highly variable functional disease progression in which the relationship of function to some patient reported outcome measures (PROMs) has not been previously reported. This analysis aims to identify the suitability of PROMs and their association with motor performance.Two-hundred and four patients with dysferlinopathy were identified in the Jain Foundation's Clinical Outcome Study in Dysferlinopathy from 14 sites in 8 countries. All patients completed the following PROMs: Individualized Neuromuscular Quality of Life Questionnaire (INQoL), International Physical Activity Questionnaire (IPAQ), and activity limitations for patients with upper and/or lower limb impairments (ACTIVLIMs). In addition, nonambulant patients completed the Egen Klassifikation Scale (EK). Assessments were conducted annually at baseline, years 1, 2, 3, and 4. Data were also collected on the North Star Assessment for Limb Girdle Type Muscular Dystrophies (NSAD) and Performance of Upper Limb (PUL) at these time points from year 2. Data were analyzed using descriptive statistics and Rasch analysis was conducted on ACTIVLIM, EK, INQoL. For associations, graphs (NSAD with ACTIVLIM, IPAQ and INQoL and EK with PUL) were generated from generalized estimating equations (GEE). The ACTIVLIM appeared robust psychometrically and was strongly associated with the NSAD total score (Pseudo R² 0.68). The INQoL performed less well and was poorly associated with the NSAD total score (Pseudo R² 0.18). EK scores were strongly associated with PUL (Pseudo R² 0.69). IPAQ was poorly associated with NSAD scores (Pseudo R² 0.09). This study showed that several of the chosen PROMs demonstrated change over time and a good association with functional outcomes. An alternative quality of life measure and method of collecting data on physical activity may need to be selected for assessing dysferlinopathy.

Instruments to assess upper-limb function in children and adolescents with neuromuscular diseases: a systematic review

AIM

To synthesize clinical and scientific evidence regarding the instruments available to assess upper-limb function in paediatric patients with neuromuscular disease (NMD).

METHOD

This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses and COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) guidelines (Prospective Registry of Systematic Reviews no. CRD42020140343). Two independent reviewers searched the PubMed/MEDLINE, LILACS, Embase, and Scopus databases. Inclusion criteria were cross-sectional or longitudinal studies or randomized controlled trials that used scales or questionnaires to assess upper-limb function in paediatric patients with NMDs. The COSMIN Risk of Bias checklist and criteria for good measurement properties were applied to assess the methodological quality of the instruments.

RESULTS

In total, 34 articles and 12 instruments were included. The Brooke Upper Extremity (n=16) and Performance of Upper Limb (PUL) (n=12) instruments were the most used tools. The PUL and Duchenne muscular dystrophy (DMD) Upper Limb patient-reported outcome measures (PROMs) tested more measurement properties and provided higher methodological quality scores for patients with DMD. Likewise, the Revised Upper Limb Module (RULM) was the most suitable instrument for patients with spinal muscular atrophy. No instrument has been devised to assess upper-limb function in patients with Charcot-Marie-Tooth disease and no other disease-specific instruments were found.

INTERPRETATION

The PUL, DMD Upper Limb PROM, and RULM are the most suitable instruments to assess upper-limb function in the two most prevalent paediatric NMDs. The identified gaps and methodological flaws of the available instruments indicate a need to develop high-quality instruments to assess other types of paediatric NMDs. What this paper adds The most suitable observer-rater instrument to assess upper-limb function in Duchenne muscular dystrophy (DMD) is the Performance of Upper Limb. The most suitable observer-rater instrument to assess upper-limb function in spinal muscular atrophy is the Revised Upper Limb Module. The DMD Upper Limb patient-reported outcome measure is recommended to assess the upper-limb performance of patients with DMD. Literature gaps and methodological flaws indicate the need to develop high-quality instruments to assess other types of paediatric neuromuscular disease.

Upper limb disease evolution in exon 53 skipping eligible patients with Duchenne muscular dystrophy

OBJECTIVE

To understand the natural disease upper limb progression over 3 years of ambulatory and non-ambulatory patients with Duchenne muscular dystrophy (DMD) using functional assessments and quantitative magnetic resonance imaging (MRI) and to exploratively identify prognostic factors.

METHODS

Forty boys with DMD (22 non-ambulatory and 18 ambulatory) with deletions in dystrophin that make them eligible for exon 53-skipping therapy were included. Clinical assessments, including Brooke score, motor function measure (MFM), hand grip and key pinch strength, and upper limb distal coordination and endurance (MoviPlate), were performed every 6 months and quantitative MRI of fat fraction (FF) and lean muscle cross sectional area (flexor and extensor muscles) were performed yearly.

RESULTS

In the whole population, there were strong nonlinear correlations between outcome measures. In non-ambulatory patients, annual changes over the course of 3 years were detected with high sensitivity standard response mean (|SRM| ≥0.8) for quantitative MRI-based FF, hand grip and key pinch, and MFM. Boys who presented with a FF<20% and a grip strength >27% were able to bring a glass to their mouth and retained this ability in the following 3 years. Ambulatory patients with grip strength >35% of predicted value and FF <10% retained ambulation 3 years later.

INTERPRETATION

We demonstrate that continuous decline in upper limb strength, function, and MRI measured muscle structure can be reliably measured in ambulatory and non-ambulatory boys with DMD with high SRM and strong correlations between outcomes. Our results suggest that a combination of grip strength and FF can be used to predict important motor milestones.

Effect of Testosterone Treatment for Delayed Puberty in Duchenne Muscular Dystrophy

OBJECTIVE

To evaluate the impact of pubertal induction with testosterone on bone health, body composition, and motor function in boys with Duchenne muscular dystrophy (DMD) receiving long-term glucocorticoid.

STUDY DESIGN

A retrospective, observational, pre-post study investigating the impact of testosterone therapy on bone mass accrual, vertebral fracture incidence, body composition, motor function, and quality of life in boys with DMD. All those boys aged ≥14 years, on chronic steroid therapy, who had delayed puberty, and were receiving oral testosterone or oral and then transitioned to intramuscular testosterone, to complete virilization, were included. Prior/concomitant zoledronic acid use was included. The primary outcome was lumbar spine areal bone mineral density (BMD LS).

RESULTS

Puberty was induced, using oral testosterone undecanoate in 16 individuals, 10 of whom had transited to intramuscular testosterone at time of assessment. Median age at testosterone onset was 14.5 years (range 14-17.7). Median duration of testosterone therapy was 2.5 years (range 1.0-4.5). There was statistically significant increase in median BMD LS (0.523-0.700, p < 0.001) and median annualized percentage change of BMD LS (-1.34 to +10.08%, p < 0.001), with median Tanner stage 4 at evaluation (range 2-4). Ten of 14 assessed had no progression in vertebral fractures. Fat mass index (FMI) standard deviation score (SDS), lean body mass index (LBMI) SDS, and percentage change of FMI and LBMI were statistically unchanged. Cardiac function remained stable. Motor function in non-ambulatory individuals with Egen Klassifikation scores improved in 7 of 8.

CONCLUSION

Testosterone for delayed puberty acted as an adjunct to bisphosphonates to increase bone density and stabilize vertebral fracture in most boys with DMD.

Test-retest reliability of the Performance of Upper Limb (PUL) module for muscular dystrophy patients

The Performance of the Upper Limb (PUL) module is an externally-assessed clinical scale, initially designed for the Duchenne muscular dystrophy population. It provides an upper extremity functional score suitable for both weaker ambulatory and non-ambulatory phases up to the severely impaired patients. It is capable of characterizing overall progression and severity of disease and of tracking the stereotypical proximal-to-distal progressive loss of upper limb function in muscular dystrophy. Since the PUL module has been validated only with Duchenne patients, its use also for Becker and Limb-Girdle muscular dystrophy patients has been here evaluated, to verify its reliability and extend its use. In particular, two different assessors performed this scale on 32 dystrophic subjects in two consecutive days. The results showed that the PUL module has high reliability, both absolute and relative, based on the calculation of Pearson's r (0.9942), Intraclass Correlation Coefficient (0.9943), Standard Error of Measurement (1.36), Minimum Detectable Change (3.77), and Coefficient of Variation (3%). The Minimum Detectable Change, in particular, can be used in clinical trials to perform a comprehensive longitudinal evaluation of the effects of interventions with the lapse of time. According to this analysis, an intervention is effective if the difference in the PUL score between subsequent evaluation points is equal or higher than 4 points; otherwise, the observed effect is not relevant. Inter-rater reliability with ten different assessors was evaluated, and it has been demonstrated that deviation from the mean is lower than calculated Minimum Detectable Change. The present work provides evidence that the PUL module is a reliable and valid instrument for measuring upper limb ability in people with different forms of muscular dystrophy. Therefore, the PUL module might be extended to other pathologies and reliably used in multicenter settings.

Respiratory Function and Upper Extremity Functional Activity Performance in People With Dementia: A Shout for Attention

The aim of this study was to explore respiratory function and upper extremity functional activity in people with dementia (PWD) and the associations between these variables and cognitive function (n = 22 institutionalized PWD, 28 community-dwelling PWD, and 26 healthy older people). All measures were significantly lower in PWD who live in an institution, such as a nursing home or long-term care facility or who attend adult daycare than PWD who live in a community dwelling . The values from these two groups were significantly lower than those from healthy older people. Moderate to high negative correlations between upper extremity functional activity and respiratory function (-.73 < rs < -.49) and cognitive function (rs = -.83), and between cognitive function and respiratory function (-.74 < rs < -.58) were identified (p < .001). When adjusted for cognitive function (-.38 < rs < -.29; p < .05), the association between upper limb functional activity and respiratory function decreased. The decline demonstrates the importance of physical activity and cognitive and respiratory function in PWD.

Pulmonary and upper limbs function in children with early stage Duchenne muscular dystrophy compared to their healthy peers

BACKGROUND

Pulmonary and upper limbs function of children with Duchenne muscular dystrophy (DMD) are known to deteriorate throughout the disease process. However, there is a lack of information on the extent of impairments in the early stages of DMD when compared to healthy peers.

OBJECTIVE

To investigate to what extent pulmonary and upper limbs function of children with early stage DMD are impaired.

METHODS

Sixty-one children participated in the study: 31 with Grade 1 DMD (study group) according to the Brooke Upper and Lower Extremity Functional Classification Systems, and 30 age matched healthy peers (control group). Pulmonary function was determined with pulmonary function tests. The Performance of Upper Limb test was used to evaluate the upper limbs function.

RESULTS

Study and control groups were homogenous in terms of physical characteristics (p>0.05). Pulmonary and upper limbs function of children with DMD were about 85% and 93% of healthy peers, respectively.

CONCLUSION

This study provides evidence for deterioration of pulmonary and upper limbs function in children with early stage DMD. Better knowledge of deterioration rate over time may help therapists to better plan and update their plan of care.

Diagnosis and management of Duchenne muscular dystrophy, part 1: diagnosis, and neuromuscular, rehabilitation, endocrine, and gastrointestinal and nutritional management

Since the publication of the Duchenne muscular dystrophy (DMD) care considerations in 2010, multidisciplinary care of this severe, progressive neuromuscular disease has evolved. In conjunction with improved patient survival, a shift to more anticipatory diagnostic and therapeutic strategies has occurred, with a renewed focus on patient quality of life. In 2014, a steering committee of experts from a wide range of disciplines was established to update the 2010 DMD care considerations, with the goal of improving patient care. The new care considerations aim to address the needs of patients with prolonged survival, to provide guidance on advances in assessments and interventions, and to consider the implications of emerging genetic and molecular therapies for DMD. The committee identified 11 topics to be included in the update, eight of which were addressed in the original care considerations. The three new topics are primary care and emergency management, endocrine management, and transitions of care across the lifespan. In part 1 of this three-part update, we present care considerations for diagnosis of DMD and neuromuscular, rehabilitation, endocrine (growth, puberty, and adrenal insufficiency), and gastrointestinal (including nutrition and dysphagia) management.