Survival in Duchenne muscular dystrophy: improvements in life expectancy since 1967 and the impact of home nocturnal ventilation

2022 HRS expert consensus statement on evaluation and management of arrhythmic risk in neuromuscular disorders

This international multidisciplinary document is intended to guide electrophysiologists, cardiologists, other clinicians, and health care professionals in caring for patients with arrhythmic complications of neuromuscular disorders (NMDs). The document presents an overview of arrhythmias in NMDs followed by detailed sections on specific disorders: Duchenne muscular dystrophy, Becker muscular dystrophy, and limb-girdle muscular dystrophy type 2; myotonic dystrophy type 1 and type 2; Emery-Dreifuss muscular dystrophy and limb-girdle muscular dystrophy type 1B; facioscapulohumeral muscular dystrophy; and mitochondrial myopathies, including Friedreich ataxia and Kearns-Sayre syndrome, with an emphasis on managing arrhythmic cardiac manifestations. End-of-life management of arrhythmias in patients with NMDs is also covered. The document sections were drafted by the writing committee members according to their area of expertise. The recommendations represent the consensus opinion of the expert writing group, graded by class of recommendation and level of evidence utilizing defined criteria. The recommendations were made available for public comment; the document underwent review by the Heart Rhythm Society Scientific and Clinical Documents Committee and external review and endorsement by the partner and collaborating societies. Changes were incorporated based on these reviews. By using a breadth of accumulated available evidence, the document is designed to provide practical and actionable clinical information and recommendations for the diagnosis and management of arrhythmias and thus improve the care of patients with NMDs.

Prognostic factors, disease course, and treatment efficacy in Duchenne muscular dystrophy: A systematic review and meta-analysis

INTRODUCTION/AIMS

Prognostic factors in Duchenne muscular dystrophy (DMD) predict the disease course and may help individualize patient care. The aim was to summarize the evidence on prognostic factors that may support treatment decisions.

METHODS

We searched six databases for prospective studies that each included ≥50 DMD patients with a minimum follow-up of 1 y. Primary outcomes were age at loss of ambulation (LoA), pulmonary function (forced vital capacity percent of predicted, FVC%p), and heart failure.

RESULTS

Out of 5074 references, 59 studies were analyzed. Corticosteroid use was associated with a delayed LoA (pooled effect hazard ratio [HR] 0.42, 95% confidence interval [CI] 0.23-0.75, I2 94%), better pulmonary function tests (higher peak FVC%, prolonged time with FVC%p > 50%, and reduced need for assisted ventilation) and delayed cardiomyopathy. Longer corticosteroid treatment was associated with later LoA (>1 y compared to <1 y; pooled HR: 0.50, 95% CI 0.27-0.90) and early treatment start (aged <5 y) may be associated with early cardiomyopathy and higher fracture risk. Genotype appeared to be an independent driver of LoA in some studies. Higher baseline physical function tests (e.g., 6-minute walk test) were associated with delayed LoA. Left ventricular dysfunction and FVC <1 L increased and the use of angiotensin-converting enzyme (ACE) inhibitors reduced the risk of heart failure and death. Fusion surgery in scoliosis may potentially preserve pulmonary function.

DISCUSSION

Prognostic factors that may inform clinical decisions include age at corticosteroid treatment initiation and treatment duration, ACE-inhibitor use, baseline physical function tests, pulmonary function, and cardiac dysfunction.

Influence of β1 Adrenergic Receptor Genotype on Longitudinal Measures of Left Ventricular Ejection Fraction and Responsiveness to ß-Blocker Therapy in Patients With Duchenne Muscular Dystrophy

The purpose of this study was to determine whether the longitudinal progression of decline in left ventricular ejection fraction (LVEF) in Duchenne muscular dystrophy (DMD) patients is moderated by ADRB1 genotype and whether the efficacy of ß-blocker therapy is influenced by genotype status. About 147 DMD patients (6-34 years.) were analyzed with a focus on β₁ adrenergic receptor (ADRB1) genotype variants. Patients were grouped by ADRB1 genotype resulting in Gly389 patients and Arg389 patients. A generalized additive mixed effects model was used to examine differences in the nonlinear trend of LVEF across patient ages between genotype groups and for ß-blocker use. Both genotype groups displayed a progressive decline in LVEF starting around the mean age of ambulation loss (~12 years). However, there was no difference between genotype groups in the progression of decline in LVEF. There was a significant effect of ß-blocker use on longitudinal LVEF, wherein patients on ß-blockers had systematically lower LVEF when compared to patients not on ß-blockers. However, the effect of ß-blocker therapy on LVEF was not affected by ADRB1 genotype. The current study did not demonstrate an influence of patient ADRB1 genotype on longitudinal LVEF in our cohort. Despite previous literature suggesting a positive influence of ß-blocker use on cardiac function in DMD patients and of an ADRB1 genotypic difference in responsiveness to ß-blocker use, we did not observe this in our cohort. Interestingly, our cohort did not demonstrate a positive influence of ß-blocker use on LVEF measures.

Cardiac and Pulmonary Management Status of Duchenne Muscular Dystrophy in South Korea Based on Data From the National Health Insurance Database

Background and Purpose

The purpose of this study was to determine the cardiac and pulmonary management status of patients with Duchenne muscular dystrophy (DMD) in South Korea based on the Korean National Health Insurance database.

Methods

This study used data of patients with code G71.0 in the National Health Information database, and also those with the special case of code V012. Cardiac function was assessed based on whether echocardiography and 24-h electrocardiography were performed, as well as the frequency of these investigations. Furthermore, information on the use of angiotensin-converting enzyme inhibitors (ACEi), angiotensin II receptor blockers (ARB), and beta blockers (BB) in the drug benefit list was checked. Medical charge records were also checked regarding the prescription of respiratory functional assessments and treatments.

Results

The diagnostic criteria were met by 479 patients, with 41% of these patients receiving a cardiac evaluation, 29.8% being prescribed ACEi at 14.4±3.7 years of age, 59.5% undergoing pulmonary function tests, and 42.1% received pulmonary rehabilitation. The age at receiving ventilator support was 19.4±2.7 years. The frequency of cardiac and respiratory function tests increased with age, but the interval between tests was longer than the recent DMD care recommendations. The trend of taking ACEi, ARB, and BB for cardiac management in South Korea did not change during the study analysis period.

Conclusions

The findings of this study will contribute to recognizing the current status and the importance of applying an anticipatory approach to cardiopulmonary function in DMD patients.

A Comparison of Caregiver and Patient Preferences for Treating Duchenne Muscular Dystrophy

Background and Objectives

Caregivers routinely inform medical and regulatory decision making in rare pediatric diseases. While differences in treatment preferences across caregivers and patients have been observed for Duchenne muscular dystrophy, this evidence was limited by small samples of patients and results were confounded by patient age and disease progression. We tested caregiver and patient preference concordance for treating Duchenne.

Methods

Preferences and demographic/clinical information from 115 caregivers and 107 patients were collected in an international study (response = 80%) using a previously developed discrete-choice experiment consisting of 12 experimentally controlled choice tasks. Each task presented two profiles that varied across four attributes: disease progression, drug failure probability, kidney damage risk, and fracture risk. Caregivers and patients were matched 1:1 based on patient age. We tested for concordance across each task and by comparing caregivers’ and patients’ maximum acceptable risk of drug failure, kidney damage, and fracture for a slowing of disease progression.

Results

The final analysis included 77 caregivers and 77 patients. No differences were observed in nationality (p = 0.969), disease stage (p = 0.180), or demographic/clinical factors (p = 0.093–0.857); however, patients were more optimistic (p = 0.030). Caregivers and patients chose similarly across tasks (p = 0.101–0.993). To slow disease progression by 1 year, caregivers and patients would tolerate a 9% and 11% increase in drug failure probability, respectively (p = 0.267). Alternatively, they would accept a 3% and 4% increase in the risk of kidney damage (p = 0.719) or a 15% and 20% increase in the risk of fracture (p = 0.534).

Conclusions

Caregivers and patients had concordant preferences for treating Duchenne. Providers and regulators can trust both caregiver and patient report of preferences to inform medical decision making.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40271-022-00574-y.

Bioenergetic and Metabolic Impairments in Induced Pluripotent Stem Cell-Derived Cardiomyocytes Generated from Duchenne Muscular Dystrophy Patients

Duchenne muscular dystrophy (DMD) is caused by mutations in the dystrophin gene and dilated cardiomyopathy (DCM) is a major cause of morbidity and mortality in DMD patients. We tested the hypothesis that DCM is caused by metabolic impairments by employing induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) generated from four DMD patients; an adult male, an adult female, a 7-year-old (7y) male and a 13-year-old (13y) male, all compared to two healthy volunteers. To test the hypothesis, we measured the bioenergetics, metabolomics, electrophysiology, mitochondrial morphology and mitochondrial activity of CMs, using respirometry, LC–MS, patch clamp, electron microscopy (EM) and confocal microscopy methods. We found that: (1) adult DMD CMs exhibited impaired energy metabolism and abnormal mitochondrial structure and function. (2) The 7y CMs demonstrated arrhythmia-free spontaneous firing along with “healthy-like” metabolic status, normal mitochondrial morphology and activity. In contrast, the 13y CMs were mildly arrhythmogenic and showed adult DMD-like bioenergetics deficiencies. (3) In DMD adult CMs, mitochondrial activities were attenuated by 45–48%, whereas the 7y CM activity was similar to that of healthy CMs. (4) In DMD CMs, but not in 7y CMs, there was a 75% decrease in the mitochondrial ATP production rate compared to healthy iPSC-CMs. In summary, DMD iPSC-CMs exhibit bioenergetic and metabolic impairments that are associated with rhythm disturbances corresponding to the patient’s phenotype, thereby constituting novel targets for alleviating cardiomyopathy in DMD patients.

Respiratory Function and Sleep Disordered Breathing in Pediatric Duchenne Muscular Dystrophy

BACKGROUND

The decline of respiratory function in Duchenne muscular dystrophy (DMD) is associated with sleep disordered breathing (SDB) and alteration of nocturnal gas exchange, first manifesting as nocturnal hypoventilation (NH). However, the correlation between pulmonary function measured by spirometry (PFT) and the onset of SDB with or without NH is unclear.

AIM

To identify the prevalence and features of SDB and to investigate the relationship between lung function determined by forced vital capacity (FVC) and sleep abnormalities in a large paediatric DMD population.

METHODS

Retrospective, single-center cohort study. FVC% predicted (FVC%) was calculated using predicted equations from the Global Lung Function Initiative. NH was defined by transcutaneous (tc) CO2 >50 mmHg for >25% of total sleep time (TST); borderline NH by a mean tcCO2 between 45-50mmHg or tcCO2>50mmHg for ≤25% of TST; Clinically meaningful obstructive sleep apnea (OSA) by obstructive Apnea-Hypopnea Index >5. The sensitivity, specificity, positive and negative predictive value of FVC<50% to indicate presence of nocturnal hypoventilation were calculated.

RESULTS

134 patients underwent 284 sleep studies and 1222 PFT. Mean (SD) age at first and last sleep study was 12.9 (2.7) and 14.3 (2.6) years. Borderline NH (n=31) was detected in both ambulant and early-non ambulant subjects, while 100% of NH cases (n=14) were non-ambulant. NH was detected in 4/14 patients despite an FVC>50%. Seventeen/26 patients with OSA presented with concomitant NH or borderline NH. FVC<50% was associated with NH indicating a sensitivity and specificity of 73% and 86%, respectively. Positive and negative predictive value were 32% and 97% respectively. PFT showed a non-linear, sudden FVC% decline in 18% of cases.

CONCLUSIONS

FVC% <50 was associated with NH in close to a third of patients. CO2 elevation can be associated with obstructive/pseudo-obstructive events and was also observed in early non-ambulant cases or in the presence of FVC>50%. These results are relevant for the clinical management of SDB.

Emergency department care of patients with Duchenne muscular dystrophy

Patients with Duchenne muscular dystrophy are living longer and are increasingly seen in Emergency Departments. Though the most common cause of death remains progressive respiratory failure, increased life expectancies have unmasked the significance of progressive myocardial dysfunction, now associated with nearly 40% of mortalities in the DMD population. Cardiac complications such as arrhythmias and cardiomyopathy are becoming ever more widely recognized. Emergency physicians may encounter DMD patients with untreated, undiagnosed or worsening of known heart disease. This review will initially familiarize the emergency physician with the pathophysiology and lifetime trajectory of care for these patients before describing specific emergency department evaluation and treatment.

Responsiveness and Minimal Clinically Important Difference of the Chinese Version of the Motor Function Measure-32 in Children and Adolescents with Duchenne Muscular Dystrophy

PURPOSE

This study aimed to examine the responsiveness and minimal clinically important difference of the Motor Function Measure 32-Chinese version (MFM 32-CN) in children and adolescents with Duchenne muscular dystrophy (DMD).

METHODS

This observational, prospective cohort study assessed changes in motor function over 12 months using the MFM 32-CN in 108 pediatric patients with DMD.

RESULTS

Moderate to high internal responsiveness was found for MFM total, D1, and D2 scores (SRM = 0.46-0.83). Sufficient external responsiveness was observed in all MFM scores, as determined by a good correlation with the Patient Global Impression of Change (PGIC) ratings (r = 0.54-0.72, p < .01). The estimated MCID values derived from different anchor-based methods ranged from 4.7 to 6.0, with a median of 5.0 points (%).

CONCLUSION

The MFM 32-CN demonstrates sufficient internal and external responsiveness as a measure of motor function in children and adolescents with DMD. The present study established the MCID of MFM-32 in pediatric patients with DMD.

Sunitinib inhibits STAT3 phosphorylation in cardiac muscle and prevents cardiomyopathy in the mdx mouse model of Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is a fatal X-linked genetic disorder affecting approximately 1 in 5000 male births worldwide. DMD is caused by mutations in the dystrophin gene. Dystrophin is essential for maintaining muscle cell membrane integrity and stability by linking the cytoskeleton to the extracellular matrix, which protects myofibers from contraction-induced damage. Loss of dystrophin leads to mechanically induced skeletal and cardiac muscle damage. Although the disease is not evident in DMD patients at birth, muscular dystrophy rapidly progresses and results in respiratory and cardiac muscle failure as early as the teenage years. Premature death in DMD patients is due to cardiac arrhythmias and left ventricular dysfunction. Currently, there is no effective treatment for DMD-related cardiac failure. Recently, we have shown that a Food and Drug Administration-approved small molecule, sunitinib, a multi-targeted tyrosine kinase inhibitor can mitigate skeletal muscle disease through an increase in myogenic capacity, cell membrane integrity, and improvement of skeletal muscle function via regulation of STAT3-related signaling pathway. Chronic activation of STAT3 has been shown to promote cardiac hypertrophy and failure. In this study, we examined the effects of long-term sunitinib treatment on cardiac pathology and function. Our results showed sunitinib treatment reduced STAT3 phosphorylation in the heart muscle of mdx mice, improved cardiac electrical function, increased cardiac output and stroke volume, decreased ventricular hypertrophy, reduced cardiomyocytes membrane damage, fibrotic tissue deposition and slightly decreased cardiac inflammation. Together, our studies support the idea that sunitinib could serve as a novel treatment to slow cardiomyopathy progression in DMD. One Sentence Summary In this study, we determined if sunitinib, a Food and Drug Administration-approved drug, could reduce the pathology and improve cardiac function in an animal model for DMD.

Society for Cardiovascular Magnetic Resonance/European Society of Cardiovascular Imaging/American Society of Echocardiography/Society for Pediatric Radiology/North American Society for Cardiovascular Imaging Guidelines for the use of cardiovascular magnetic resonance in pediatric congenital and acquired heart disease : Endorsed by The American Heart Association

Cardiovascular magnetic resonance (CMR) has been utilized in the management and care of pediatric patients for nearly 40 years. It has evolved to become an invaluable tool in the assessment of the littlest of hearts for diagnosis, pre-interventional management and follow-up care. Although mentioned in a number of consensus and guidelines documents, an up-to-date, large, stand-alone guidance work for the use of CMR in pediatric congenital 36 and acquired 35 heart disease endorsed by numerous Societies involved in the care of these children is lacking. This guidelines document outlines the use of CMR in this patient population for a significant number of heart lesions in this age group and although admittedly, is not an exhaustive treatment, it does deal with an expansive list of many common clinical issues encountered in daily practice.

Society for Cardiovascular Magnetic Resonance/European Society of Cardiovascular Imaging/American Society of Echocardiography/Society for Pediatric Radiology/North American Society for Cardiovascular Imaging Guidelines for the Use of Cardiac Magnetic Resonance in Pediatric Congenital and Acquired Heart Disease: Endorsed by The American Heart Association

Cardiovascular magnetic resonance has been utilized in the management and care of pediatric patients for nearly 40 years. It has evolved to become an invaluable tool in the assessment of the littlest of hearts for diagnosis, pre-interventional management and follow-up care. Although mentioned in a number of consensus and guidelines documents, an up-to-date, large, stand-alone guidance work for the use of cardiovascular magnetic resonance in pediatric congenital 36 and acquired 35 heart disease endorsed by numerous Societies involved in the care of these children is lacking. This guidelines document outlines the use of cardiovascular magnetic resonance in this patient population for a significant number of heart lesions in this age group and although admittedly, is not an exhaustive treatment, it does deal with an expansive list of many common clinical issues encountered in daily practice.

Selected clinical and demographic factors and all-cause mortality among individuals with Duchenne muscular dystrophy in the Muscular Dystrophy Surveillance, Tracking, and Research Network

Population-based estimates of survival among individuals with Duchenne muscular dystrophy (DMD) living in the United States are lacking. It is also unclear whether the association between glucocorticoid use and all-cause mortality persists in the context of other common treatments (cardiac medication, cough-assist, bilevel positive airway pressure, and scoliosis surgery) observed to delay mortality. Among 526 individuals identified by the Muscular Dystrophy Surveillance, Tracking, and Research Network, the estimated median survival time from birth was 23.7 years. Current glucocorticoid users had a lower hazard of mortality than non-users. Individuals who ever had scoliosis surgery had a lower hazard of mortality than individuals who did not have scoliosis surgery. Individuals who ever used cough assist had a lower hazard of mortality than individuals who never used cough assist. Non-Hispanic Black individuals had a higher hazard of mortality than non-Hispanic White individuals. No differences in hazards of mortality were observed between ever versus never use of cardiac medication and ever versus never use of bilevel positive airway pressure. The glucocorticoid observation is consistent with the 2018 Care Considerations statement that glucocorticoid use continues in the non-ambulatory phase. Our observations may inform the clinical care of individuals living with DMD.

Cardiovascular Disease in Duchenne Muscular Dystrophy

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Cardiomyopathy is the leading cause of death in patients with DMD.

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DMD has no cure, and there is no current consensus for treatment of DMD cardiomyopathy.

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This review discusses therapeutic strategies to potentially reduce or prevent cardiac dysfunction in DMD patients.

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Additional studies are needed to firmly establish optimal treatment modalities for DMD cardiomyopathy.

Duchenne muscular dystrophy (DMD) is a devastating disease affecting approximately 1 in every 3,500 male births worldwide. Multiple mutations in the dystrophin gene have been implicated as underlying causes of DMD. However, there remains no cure for patients with DMD, and cardiomyopathy has become the most common cause of death in the affected population. Extensive research is under way investigating molecular mechanisms that highlight potential therapeutic targets for the development of pharmacotherapy for DMD cardiomyopathy. In this paper, the authors perform a literature review reporting on recent ongoing efforts to identify novel therapeutic strategies to reduce, prevent, or reverse progression of cardiac dysfunction in DMD.

Clinical Implications of Routine Monitoring of Pulmonary Function and Ventilation in Patients with Duchenne Muscular Dystrophy

PURPOSE

To investigate the effect of regular monitoring of pulmonary function and ventilatory status on the initiation of non-invasive ventilation (NIV) between patients who were routinely monitored before receiving NIV and those who were not.

MATERIALS AND METHODS

This retrospective cohort study included subjects with Duchenne muscular dystrophy (DMD) who first received NIV between 2010 and 2019. The subjects were assigned to either the regular-follow-up (REG) group or the non-REG group, according to their follow-up status, before initiating NIV. We compared the number of emergent cases, the results of nocturnal ventilatory monitoring, and the pulmonary function of each group at initial ventilatory support.

RESULTS

In total, 73 subjects were enrolled in the REG group and 47 subjects in the non-REG group. There were significantly more emergency cases due to respiratory insufficiency in the non-REG group (12/47, 25.5%) than in the REG group (3/73, 4.1%). At the time of initial ventilatory support, hypoventilatory symptoms were more common and relatively severe in the non-REG group (37/47, 78.7%) than in the REG group (18/73, 24.7%). The average age at initial ventilatory support of the non-REG group was 2.15 years older than that of the subjects in the REG group. Moreover, subjects who were not regularly monitored exhibited greater deterioration in pulmonary function compared to those who were regularly followed up.

CONCLUSION

Regular evaluation of pulmonary function and ventilatory status before the onset of ventilatory insufficiency is crucial to reduce the risk of patients with DMD requiring emergency care due to ventilatory insufficiency.

Breathing in Duchenne muscular dystrophy: Translation to therapy

Duchenne muscular dystrophy (DMD) is an X-linked neuromuscular disease caused by a deficiency in dystrophin - a structural protein which stabilizes muscle during contraction. Dystrophin deficiency adversely affects the respiratory system leading to sleep-disordered breathing, hypoventilation, and weakness of the expiratory and inspiratory musculature, which culminate in severe respiratory dysfunction. Muscle degeneration associated respiratory impairment in neuromuscular disease is a result of disruptions at multiple sites of the respiratory control network, including sensory and motor pathways. As a result of this pathology, respiratory failure is a leading cause of premature death in DMD patients. Currently available treatments for DMD respiratory insufficiency attenuate respiratory symptoms without completely reversing the underlying pathophysiology. This underscores the need to develop curative therapies to improve quality of life and longevity of DMD patients. This review summarises research findings on the pathophysiology of respiratory insufficiencies in DMD disease in humans and animal models, the clinical interventions available to ameliorate symptoms, and gene-based therapeutic strategies uncovered by preclinical animal studies. Abstract figure legend: Summary of the therapeutic strategies for respiratory insufficiency in DMD (Duchenne muscular dystrophy). Treatment options currently in clinical use only attenuate respiratory symptoms without reversing the underlying pathology of DMD-associated respiratory insufficiencies. Ongoing preclinical and clinical research is aimed at developing curative therapies that both improve quality of life and longevity of DMD patients. AAV - adeno-associated virus, PPMO - Peptide-conjugated phosphorodiamidate morpholino oligomer This article is protected by copyright. All rights reserved.

Protocol-driven early tracheal extubation in patients with flaccid neuromuscular scoliosis and pre-existing lung disease

PURPOSE

To review the results of a postoperative respiratory pathway for patients with muscular dystrophy (MD) and spinal muscular atrophy (SMA) undergoing spinal surgery.

METHODS

With IRB approval, a retrospective review was done on all patients with SMA and MD undergoing spinal surgery on a neuromuscular protocol. Baseline demographics, perioperative results, and long-term outcomes were collected. Per the protocol, patients remained intubated after surgery and were transported to the intensive care unit (ICU) for extubation. We present the results of protocol implementation and compare patients with MD to those with SMA.

RESULTS

Twenty-four patients were treated using the protocol. Average age was 13.1 years. Severe restrictive lung disease was present in 75% of patients. Nocturnal BiPAP was required in 68% of patients. Average number of instrumented levels was 17. All patients were immediately extubated upon entering the ICU. There were three respiratory complications and only was patient was re-intubated. Average ICU stay was 1.8 days and average hospital length of stay was 6.7 days. No differences in postoperative inspiratory or expiratory positive airway pressures were observed between the MD and SMA groups.

CONCLUSION

Through a multidisciplinary neuromuscular protocol, excellent clinical outcomes were achieved in patients with neuromuscular scoliosis and restrictive lung disease, with complication rates and length of stay significantly lower than previously published data.

LEVEL OF EVIDENCE

IV.

Direct costs of adhering to selected Duchenne muscular dystrophy Care Considerations: Estimates from a midwestern state

INTRODUCTION/AIMS

The multidisciplinary Duchenne muscular dystrophy (DMD) Care Considerations were developed to standardize care and improve outcomes. We provide cumulative cost estimates for selected key preventive (ie, excluding new molecular therapies and acute care) elements of the care considerations in eight domains (neuromuscular, rehabilitation, respiratory, cardiac, orthopedic, gastrointestinal, endocrine, psychosocial management) independent of completeness of uptake or provision of nonpreventive care.

METHODS

We used de-identified insurance claims data from a large midwestern commercial health insurer during 2018. We used Current Procedural Terminology and national drug codes to extract unit costs for clinical encounters representing key preventive elements of the DMD Care Considerations. We projected per-patient cumulative costs from ages 5 to 25 years for these elements by multiplying a schedule of recommended frequencies of preventive services by unit costs in 2018 US dollars.

RESULTS

Assuming a diagnosis at age 5 years, independent ambulation until age 11, and survival until age 25, we estimated 670 billable clinical events. The 20-year per-patient cumulative cost was $174 701 with prednisone ($2.3 million with deflazacort) and an expected total of $12 643 ($29 194) for out-of-pocket expenses associated with those events and medications.

DISCUSSION

Standardized monitoring of disease progression and treatments may reduce overall costs of illness. Costs associated with these services would be needed to quantify potential savings. Our approach demonstrates a method to estimate costs associated with implementation of preventive care schedules.

Effect of Different Corticosteroid Dosing Regimens on Clinical Outcomes in Boys With Duchenne Muscular Dystrophy: A Randomized Clinical Trial

IMPORTANCE

Corticosteroids improve strength and function in boys with Duchenne muscular dystrophy. However, there is uncertainty regarding the optimum regimen and dosage.

OBJECTIVE

To compare efficacy and adverse effects of the 3 most frequently prescribed corticosteroid regimens in boys with Duchenne muscular dystrophy.

DESIGN, SETTING, AND PARTICIPANTS

Double-blind, parallel-group randomized clinical trial including 196 boys aged 4 to 7 years with Duchenne muscular dystrophy who had not previously been treated with corticosteroids; enrollment occurred between January 30, 2013, and September 17, 2016, at 32 clinic sites in 5 countries. The boys were assessed for 3 years (last participant visit on October 16, 2019).

INTERVENTIONS

Participants were randomized to daily prednisone (0.75 mg/kg) (n = 65), daily deflazacort (0.90 mg/kg) (n = 65), or intermittent prednisone (0.75 mg/kg for 10 days on and then 10 days off) (n = 66).

MAIN OUTCOMES AND MEASURES

The global primary outcome comprised 3 end points: rise from the floor velocity (in rise/seconds), forced vital capacity (in liters), and participant or parent global satisfaction with treatment measured by the Treatment Satisfaction Questionnaire for Medication (TSQM; score range, 0 to 100), each averaged across all study visits after baseline. Pairwise group comparisons used a Bonferroni-adjusted significance level of .017.

RESULTS

Among the 196 boys randomized (mean age, 5.8 years [SD, 1.0 years]), 164 (84%) completed the trial. Both daily prednisone and daily deflazacort were more effective than intermittent prednisone for the primary outcome (P < .001 for daily prednisone vs intermittent prednisone using a global test; P = .017 for daily deflazacort vs intermittent prednisone using a global test) and the daily regimens did not differ significantly (P = .38 for daily prednisone vs daily deflazacort using a global test). The between-group differences were principally attributable to rise from the floor velocity (0.06 rise/s [98.3% CI, 0.03 to 0.08 rise/s] for daily prednisone vs intermittent prednisone [P = .003]; 0.06 rise/s [98.3% CI, 0.03 to 0.09 rise/s] for daily deflazacort vs intermittent prednisone [P = .017]; and -0.004 rise/s [98.3% CI, -0.03 to 0.02 rise/s] for daily prednisone vs daily deflazacort [P = .75]). The pairwise comparisons for forced vital capacity and TSQM global satisfaction subscale score were not statistically significant. The most common adverse events were abnormal behavior (22 [34%] in the daily prednisone group, 25 [38%] in the daily deflazacort group, and 24 [36%] in the intermittent prednisone group), upper respiratory tract infection (24 [37%], 19 [29%], and 24 [36%], respectively), and vomiting (19 [29%], 17 [26%], and 15 [23%]).

CONCLUSIONS AND RELEVANCE

Among patients with Duchenne muscular dystrophy, treatment with daily prednisone or daily deflazacort, compared with intermittent prednisone alternating 10 days on and 10 days off, resulted in significant improvement over 3 years in a composite outcome comprising measures of motor function, pulmonary function, and satisfaction with treatment; there was no significant difference between the 2 daily corticosteroid regimens. The findings support the use of a daily corticosteroid regimen over the intermittent prednisone regimen tested in this study as initial treatment for boys with Duchenne muscular dystrophy.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01603407.

Biomarkers in Duchenne Muscular Dystrophy

PURPOSE OF REVIEW

This review highlights the key studies investigating various types of biomarkers in Duchenne muscular dystrophy (DMD).

RECENT FINDINGS

Several proteomic and metabolomic studies have been undertaken in both human DMD patients and animal models of DMD that have identified potential biomarkers in DMD. Although there have been a number of proteomic and metabolomic studies that have identified various potential biomarkers in DMD, more definitive studies still need to be undertaken in DMD patients to firmly correlate these biomarkers with diagnosis, disease progression, and monitoring the effects of novel treatment strategies being developed.

Prognostic indicators of disease progression in Duchenne muscular dystrophy: A literature review and evidence synthesis

BACKGROUND

Duchenne muscular dystrophy (DMD) is a rare, severely debilitating, and fatal neuromuscular disease characterized by progressive muscle degeneration. Like in many orphan diseases, randomized controlled trials are uncommon in DMD, resulting in the need to indirectly compare treatment effects, for example by pooling individual patient-level data from multiple sources. However, to derive reliable estimates, it is necessary to ensure that the samples considered are comparable with respect to factors significantly affecting the clinical progression of the disease. To help inform such analyses, the objective of this study was to review and synthesise published evidence of prognostic indicators of disease progression in DMD. We searched MEDLINE (via Ovid), Embase (via Ovid) and the Cochrane Library (via Wiley) for records published from inception up until April 23 2021, reporting evidence of prognostic indicators of disease progression in DMD. Risk of bias was established with the grading system of the Centre for Evidence-Based Medicine (CEBM).

RESULTS

Our search included 135 studies involving 25,610 patients from 18 countries across six continents (Africa, Asia, Australia, Europe, North America and South America). We identified a total of 23 prognostic indicators of disease progression in DMD, namely age at diagnosis, age at onset of symptoms, ataluren treatment, ATL1102, BMI, cardiac medication, DMD genetic modifiers, DMD mutation type, drisapersen, edasalonexent, eteplirsen, glucocorticoid exposure, height, idebenone, lower limb surgery, orthoses, oxandrolone, spinal surgery, TAS-205, vamorolone, vitlolarsen, ventilation support, and weight. Of these, cardiac medication, DMD genetic modifiers, DMD mutation type, and glucocorticoid exposure were designated core prognostic indicators, each supported by a high level of evidence and significantly affecting a wide range of clinical outcomes.

CONCLUSION

This study provides a current summary of prognostic indicators of disease progression in DMD, which will help inform the design of comparative analyses and future data collection initiatives in this patient population.

Repeated intravenous cardiosphere-derived cell therapy in late-stage Duchenne muscular dystrophy (HOPE-2): a multicentre, randomised, double-blind, placebo-controlled, phase 2 trial

BACKGROUND

Cardiosphere-derived cells (CDCs) ameliorate skeletal and cardiac muscle deterioration in experimental models of Duchenne muscular dystrophy. The HOPE-2 trial examined the safety and efficacy of sequential intravenous infusions of human allogeneic CDCs in late-stage Duchenne muscular dystrophy.

METHODS

In this multicentre, randomised, double-blind, placebo-controlled, phase 2 trial, patients with Duchenne muscular dystrophy, aged 10 years or older with moderate upper limb impairment, were enrolled at seven centres in the USA. Patients were randomly assigned (1:1) using stratified permuted blocks to receive CAP-1002 (1·5 × 10⁸ CDCs) or placebo intravenously every 3 months for a total of four infusions. Clinicians, caregivers, patients, and clinical operations personnel were fully masked to treatment groups. The primary outcome was the change in mid-level elbow Performance of Upper Limb version 1.2 (PUL 1.2) score at 12 months, assessed in the intention-to-treat population. Safety was assessed in all individuals who received an investigational product. This trial is registered with ClinicalTrials.gov, NCT03406780.

FINDINGS

Between March 1, 2018, and March 31, 2020, 26 male patients with Duchenne muscular dystrophy were enrolled, of whom eight were randomly assigned to the CAP-1002 group and 12 to the placebo group (six were not randomised due to screening failure). In patients who had a post-treatment PUL 1.2 assessment (eight in the CAP-1002 group and 11 in the placebo group), the mean 12-month change from baseline in mid-level elbow PUL1.2 favoured CAP-1002 over placebo (percentile difference 36·2, 95% CI 12·7-59·7; difference of 2·6 points; p=0·014). Infusion-related hypersensitivity reactions without long-term sequelae were observed in three patients, with one patient discontinuing therapy due to a severe allergic reaction. No other major adverse reactions were noted, and no deaths occurred.

INTERPRETATION

CAP-1002 cell therapy appears to be safe and effective in reducing deterioration of upper limb function in patients with late-stage Duchenne muscular dystrophy. Various measures of cardiac function and structure were also improved in the CAP-1002 group compared with the placebo group. Longer-term extension studies are needed to confirm the therapeutic durability and safety of CAP-1002 beyond 12 months for the treatment of skeletal myopathy and cardiomyopathy in Duchenne muscular dystrophy.

FUNDING

Capricor Therapeutics.

A population-based study of mortality due to muscular dystrophies across a 36-year period in Spain

Muscular dystrophies (MD) are a group of rare hereditary degenerative diseases. Our aim was to analyze the mortality pattern in Spain from 1981 to 2016 to assess the temporal trend and discern possible geographic differences using population-based data. Annual deaths related to MD were obtained from the National Statistics Institute with codes 359.1 of the ICD-9 (1981–1998) and G71.0 of the ICD-10 (1999–2016). Age-adjusted mortality rates were calculated and changes in mortality trends were identified. The standardized mortality ratios (SMR) and their respective 95% confidence intervals were calculated by district for 1999–2016. Smoothed SMRs and posterior probability were also assessed and then mapped to look for patterns or geographic distribution. All rates were expressed per 1,000,000 inhabitants. A total of 2,512 deaths (73.8% men) were identified. The age-adjusted mortality rates varied from 0.63 (95% CI 0.40–0.95) in 1981 to 1.51 (95% CI 1.17–1.93) in 2016. MD mortality showed a significant increase of 8.81% per year (95% CI 5.0–12.7) from 1981 to 1990, remaining stable afterwards. Areas with risk of death higher than expected for Spain as a whole were identified, not showing a specific regional pattern. In conclusion, the rising trend in MD mortality might be attributable to advanced improvements in diagnostic techniques leading to a rise in prevalence. Further research on the districts with the highest mortality would be necessary.

Inhibition of PKCθ Improves Dystrophic Heart Phenotype and Function in a Novel Model of DMD Cardiomyopathy

Chronic cardiac muscle inflammation and subsequent fibrotic tissue deposition are key features in Duchenne Muscular Dystrophy (DMD). The treatment of choice for delaying DMD progression both in skeletal and cardiac muscle are corticosteroids, supporting the notion that chronic inflammation in the heart plays a pivotal role in fibrosis deposition and subsequent cardiac dysfunction. Nevertheless, considering the adverse effects associated with long-term corticosteroid treatments, there is a need for novel anti-inflammatory therapies. In this study, we used our recently described exercised mdx (ex mdx) mouse model characterised by accelerated heart pathology, and the specific PKCθ inhibitor Compound 20 (C20), to show that inhibition of this kinase leads to a significant reduction in the number of immune cells infiltrating the heart, as well as necrosis and fibrosis. Functionally, C20 treatment also prevented the reduction in left ventricle fractional shortening, which was typically observed in the vehicle-treated ex mdx mice. Based on these findings, we propose that PKCθ pharmacological inhibition could be an attractive therapeutic approach to treating dystrophic cardiomyopathy

Global prevalence of Duchenne and Becker muscular dystrophy: a systematic review and meta-analysis

Background

A variety of mutations in the largest human gene, dystrophin, cause a spectrum from mild to severe dystrophin-associated muscular dystrophies. Duchenne (DMD) and Becker (BMD) muscular dystrophies are located at the severe end of the spectrum that primarily affects skeletal muscle. Progressive muscle weakness in these purely genetic disorders encourages families with a positive history for genetic counseling to prevent a recurrence, which requires an accurate prevalence of the disorder. Here, we provide a systematic review and meta-analysis to determine the prevalence of DMD and BMD worldwide.

Method

The current systematic review and meta-analysis was carried out using Cochrane seven-step procedure. After determining the research question and inclusion and exclusion criteria, the MagIran, SID, ScienceDirect, WoS, ProQuest, Medline (PubMed), Embase, Cochrane, Scopus, and Google Scholar databases were searched to find relevant studies using defined keywords and all possible keyword combinations using the AND and OR, with no time limit until 2021. The heterogeneity of studies was calculated using the I² test, and the publication bias was investigated using the Begg and Mazumdar rank correlation test. Statistical analysis of data was performed using Comprehensive Meta-Analysis software (version 2).

Results

A total of 25 articles involving 901,598,055 people were included. The global prevalence of muscular dystrophy was estimated at 3.6 per 100,000 people (95 CI 2.8–4.5 per 100,000 people), the largest prevalence in the Americans at 5.1 per 100,000 people (95 CI 3.4–7.8 per 100,000 people). According to the subgroup analysis, the prevalence of DMD and BMD was estimated at 4.8 per 100,000 people (95 CI 3.6–6.3 per 100,000 people) and 1.6 per 100,000 people (95 CI 1.1–2.4 per 100,000 people), respectively.

Conclusion

Knowing the precise prevalence of a genetic disorder helps to more accurately predict the likelihood of preventing its occurrence in families. The global prevalence of DMD and BMD was very high, indicating the urgent need for more attention to prenatal screening and genetic counseling for families with a positive history.

A population-based study of scoliosis among males diagnosed with a dystrophinopathy identified by the Muscular Dystrophy Surveillance, Tracking, and Research Network (MD STARnet)

INTRODUCTION/AIMS

Scoliosis is a common comorbidity among individuals diagnosed with a dystrophinopathy. We examined associations between clinical predictors and scoliosis in childhood-onset dystrophinopathy.

METHODS

The progression and treatment of scoliosis were obtained from data collected by the US population-based Muscular Dystrophy Surveillance, Tracking, and Research Network. Associations between loss of independent ambulation (LoA) and corticosteroid use and scoliosis outcomes (ages at or exceeding Cobb angle thresholds [10°, 20°, 30°]; surgery) were estimated using Kaplan-Meier curve estimation and extended Cox regression modeling.

RESULTS

We analyzed curvature data for 513 of 1054 individuals ascertained. Overall, approximately one-half had at least one radiograph and one-quarter had a curvature of at least 20°. The average maximum curvature was 25.0° (SD = 21.5°) among all individuals and 42.8° (SD = 18.8°) among those recommended for surgery. Higher adjusted hazards ratio of curvature (aHR(curvature) [95% confidence interval]) were found among individuals with LoA compared to those without LoA (aHR(10)  = 6.2 [4.4, 8.7], aHR(20)  = 15.3 [7.4, 31.7], aHR(30)  = 31.6 [7.7, 128.9]), among individuals who did not use corticosteroids compared to those who did (aHR(10)  = 1.2 [0.9, 1.7], aHR(20)  = 1.8 [1.1, 2.7], aHR(30)  = 2.3 [1.3, 4.0]), and among non-ambulatory individuals who used corticosteroids after LoA compared to those who did not (aHR(10)  = 1.8 [1.2, 2.8], aHR(20)  = 1.6 [1.0, 2.6], aHR(30)  = 3.6 [1.6, 7.9]). Scoliosis surgery among individuals with LoA who did not use corticosteroids was more than double compared to those who used (aHR = 2.3 [1.3, 4.2]).

DISCUSSION

Our retrospective observational study suggests corticosteroids may delay spinal curvature progression and need for scoliosis surgery. Continuing corticosteroids after LoA also showed potential benefits of delaying curvature progression, additional studies are needed to confirm this finding or address the magnitude of benefit.

Nucleic Acid-Based Therapeutic Approach for Spinal and Bulbar Muscular Atrophy and Related Neurological Disorders

The recent advances in nucleic acid therapeutics demonstrate the potential to treat hereditary neurological disorders by targeting their causative genes. Spinal and bulbar muscular atrophy (SBMA) is an X-linked and adult-onset neurodegenerative disorder caused by the expansion of trinucleotide cytosine-adenine-guanine repeats, which encodes a polyglutamine tract in the androgen receptor gene. SBMA belongs to the family of polyglutamine diseases, in which the use of nucleic acids for silencing a disease-causing gene, such as antisense oligonucleotides and small interfering RNAs, has been intensively studied in animal models and clinical trials. A unique feature of SBMA is that both motor neuron and skeletal muscle pathology contribute to disease manifestations, including progressive muscle weakness and atrophy. As both motor neurons and skeletal muscles can be therapeutic targets in SBMA, nucleic acid-based approaches for other motor neuron diseases and myopathies may further lead to the development of a treatment for SBMA. Here, we review studies of nucleic acid-based therapeutic approaches in SBMA and related neurological disorders and discuss current limitations and perspectives to apply these approaches to patients with SBMA.

A Long-Term Study Evaluating the Effects of Nicorandil Treatment on Duchenne Muscular Dystrophy-Associated Cardiomyopathy in mdx Mice

BACKGROUND

Duchenne muscular dystrophy (DMD) is a neuromuscular disease caused by dystrophin gene mutations affecting striated muscle. Due to advances in skeletal muscle treatment, cardiomyopathy has emerged as a leading cause of death. Previously, nicorandil, a drug with antioxidant and nitrate-like properties, ameliorated cardiac damage and improved cardiac function in young, injured mdx mice. Nicorandil mitigated damage by stimulating antioxidant activity and limiting pro-oxidant expression. Here, we examined whether nicorandil was similarly cardioprotective in aged mdx mice.

METHODS AND RESULTS

Nicorandil (6 mg/kg) was given over 15 months. Echocardiography of mdx mice showed some functional defects at 12 months compared to wild-type (WT) mice, but not at 15 months. Disease manifestation was evident in mdx mice via treadmill assays and survival, but not open field and grip strength assays. Cardiac levels of SOD2 and NOX4 were decreased in mdx vs. WT. Nicorandil increased survival in mdx but did not alter cardiac function, fibrosis, diaphragm function or muscle fatigue.

CONCLUSIONS

In contrast to our prior work in young, injured mdx mice, nicorandil did not exert cardioprotective effects in 15 month aged mdx mice. Discordant findings may be explained by the lack of cardiac disease manifestation in aged mdx mice compared to WT, whereas significant cardiac dysfunction was previously seen with the sub-acute injury in young mice. Therefore, we are not able to conclude any cardioprotective effects with long-term nicorandil treatment in aging mdx mice.

Full-length dystrophin deficiency leads to contractile and calcium transient defects in human engineered heart tissues

Cardiomyopathy is currently the leading cause of death for patients with Duchenne muscular dystrophy (DMD), a severe neuromuscular disorder affecting young boys. Animal models have provided insight into the mechanisms by which dystrophin protein deficiency causes cardiomyopathy, but there remains a need to develop human models of DMD to validate pathogenic mechanisms and identify therapeutic targets. Here, we have developed human engineered heart tissues (EHTs) from CRISPR-edited, human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) expressing a truncated dystrophin protein lacking part of the actin-binding domain. The 3D EHT platform enables direct measurement of contractile force, simultaneous monitoring of Ca2+ transients, and assessment of myofibril structure. Dystrophin-mutant EHTs produced less contractile force as well as delayed kinetics of force generation and relaxation, as compared to isogenic controls. Contractile dysfunction was accompanied by reduced sarcomere length, increased resting cytosolic Ca2+ levels, delayed Ca2+ release and reuptake, and increased beat rate irregularity. Transcriptomic analysis revealed clear differences between dystrophin-deficient and control EHTs, including downregulation of genes related to Ca2+ homeostasis and extracellular matrix organization, and upregulation of genes related to regulation of membrane potential, cardiac muscle development, and heart contraction. These findings indicate that the EHT platform provides the cues necessary to expose the clinically-relevant, functional phenotype of force production as well as mechanistic insights into the role of Ca2+ handling and transcriptomic dysregulation in dystrophic cardiac function, ultimately providing a powerful platform for further studies in disease modeling and drug discovery.

Current Practices in Treating Cardiomyopathy and Heart Failure in Duchenne Muscular Dystrophy (DMD): Understanding Care Practices in Order to Optimize DMD Heart Failure Through ACTION

Cardiac disease has emerged as a leading cause of mortality in Duchenne muscular dystrophy in the current era. This survey sought to identify the diagnostic and therapeutic approach to DMD among pediatric cardiologists in Advanced Cardiac Therapies Improving Outcomes Network. Pediatric cardiology providers within ACTION (a multi-center pediatric heart failure learning network) were surveyed regarding their approaches to cardiac care in DMD. Thirty-one providers from 23 centers responded. Cardiac MRI and Holter monitoring are routinely obtained, but the frequency of use and indications for ordering these tests varied widely. Angiotensin converting enzyme inhibitor and aldosterone antagonist are generally initiated prior to onset of systolic dysfunction, while the indications for initiating beta-blocker therapy vary more widely. Seventeen (55%) providers report their center has placed an implantable cardioverter defibrillator in at least 1 DMD patient, while 11 providers (35%) would not place an ICD for primary prevention in a DMD patient. Twenty-three providers (74%) would consider placement of a ventricular assist device (VAD) as destination therapy (n = 23, 74%) and three providers (10%) would consider a VAD only as bridge to transplant. Five providers (16%) would not consider VAD at their institution. Cardiac diagnostic and therapeutic approaches vary among ACTION centers, with notable variation present regarding the use of advanced therapies (ICD and VAD). The network is currently working to harmonize medical practices and optimize clinical care in an era of rapidly evolving outcomes and cardiac/skeletal muscle therapies.

Differentiation of Pediatric-Onset Duchenne and Becker Muscular Dystrophy Subphenotypes Using Data from the Muscular Dystrophy Surveillance Tracking and Research Network (MD STARnet)

Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) phenotypes are used to describe disease progression in affected individuals. However, considerable heterogeneity has been observed across and within these two phenotypes, suggesting a spectrum of severity rather than distinct conditions. Characterizing the phenotypes and subphenotypes aids researchers in the design of clinical studies and clinicians in providing anticipatory guidance to affected individuals and their families. Using data from the Muscular Dystrophy Surveillance, Tracking, and Research Network (MD STARnet), we used K-means cluster analysis to group phenotypically similar males with pediatric-onset dystrophinopathy. We identified four dystrophinopathy clusters: Classical BMD, Classical DMD, late ambulatory DMD, and severe DMD. The clusters that we identified align with both 'classical' and 'non-classical' dystrophinopathy described in the literature. Individuals with dystrophinopathies have heterogenous clinical presentations that cluster into phenotypically similar groups. Use of clinically-derived phenotyping may provide a clearer understanding of disease trajectories, reduce variability in study results, and prevent exclusion of certain cohorts from analysis. Findings from studying subphenotypes may ultimately improve our ability to predict disease progression.

Mechanical ventilation in Duchenne muscular dystrophy: A pilot project in Ukraine

BACKGROUND

Home mechanical ventilation (HMV) prolongs survival in patients with Duchenne muscular dystrophy (DMD) until ±35 years of age. This study evaluates the implementation of a HMV pilot project in children with DMD in Ukraine.

METHODS

Children with DMD were invited to Kirovograd Regional Children's Clinical Hospital, Kropyvnytskyi, Ukraine, for 5 days' training with non-invasive ventilation. Donated equipment comprised second-hand Covidien PB560 ventilators from Belgium. Due to the absence of carbon dioxide pressure and pulse oximetry monitoring, indications for HMV included sleep-related symptoms, restrictive lung function test, loss of ambulation for more than 1 year, or age greater than 17 years. Master class lectures on HMV were conducted for Ukrainian doctors in conjunction with patient training.

RESULTS

Twelve Ukrainian physicians took part in face-to-face master classes and 50 Ukrainian physicians participated in online master classes. Simultaneously, eight Duchenne inpatients, mean age 15.4 (SD: 1.8) years and body mass index 25.8 (SD: 4.0), were included in the study. All patients chose nasal masks and volume-pressure-assisted control mode. After 6 weeks, one patient stopped HMV, two others used HMV partially during sleep, and 5/8 used nocturnal HMV increasingly with few complaints. Follow up via phone call was organized after hospitalization.

CONCLUSIONS

Implementation of HMV is feasible in DMD inpatients in Ukraine. In the short term, the Ukrainian parliament should recognize official centers for HMV, and define the funding policy of equipment for HMV, and its maintenance. Local distributors should deliver equipment for HMV and devices for monitoring carbon dioxide pressure and pulse oximetry in specialized centers for HMV.

Prevalence and incidence of neuromuscular conditions in the UK between 2000 and 2019: A retrospective study using primary care data

BACKGROUND

In the UK, large-scale electronic primary care datasets can provide up-to-date, accurate epidemiological information on rarer diseases, where specialist diagnoses from hospital discharges and clinic letters are generally well recorded and electronically searchable. Current estimates of the number of people living with neuromuscular disease (NMD) have largely been based on secondary care data sources and lacked direct denominators.

OBJECTIVE

To estimate trends in the recording of neuromuscular disease in UK primary care between 2000-2019.

METHODS

The Clinical Practice Research Datalink (CPRD) database was searched electronically to estimate incidence and prevalence rates (per 100,000) for a range of NMDs in each year. To compare trends over time, rates were age standardised to the most recent CPRD population (2019).

RESULTS

Approximately 13 million patients were actively registered in each year. By 2019, 28,230 active patients had ever received a NMD diagnosis (223.6), which was higher among males (239.0) than females (208.3). The most common classifications were Guillain-Barre syndrome (40.1), myasthenia gravis (33.7), muscular dystrophy (29.5), Charcot-Marie-Tooth (29.5) and inflammatory myopathies (25.0). Since 2000, overall prevalence grew by 63%, with the largest increases seen at older ages (≥65-years). However, overall incidence remained constant, though myasthenia gravis incidence has risen steadily since 2008, while new cases of muscular dystrophy fell over the same period.

CONCLUSIONS

Lifetime recording of many NMDs on primary care records exceed current estimates of people living with these conditions; these are important data for health service and care planning. Temporal trends suggest this number is steadily increasing, and while this may partially be due to better recording, it cannot be simply explained by new cases, as incidence remained constant. The increase in prevalence among older ages suggests increases in life expectancy among those living with NMDs may have occurred.

Identifying the hub genes for Duchenne muscular dystrophy and Becker muscular dystrophy by weighted correlation network analysis

Background

The goal of this study is to identify the hub genes for Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) via weighted correlation network analysis (WGCNA).

Methods

The gene expression profile of vastus lateralis biopsy samples obtained in 17 patients with DMD, 11 patients with BMD and 6 healthy individuals was downloaded from the Gene Expression Omnibus (GEO) database (GSE109178). After obtaining different expressed genes (DEGs) via GEO2R, WGCNA was conducted using R package, modules and genes that highly associated with DMD, BMD, and their age or pathology were screened. Gene Ontology (GO) and Kyoto Encyclopaedia of Genes and Genomes (KEGG) enrichment analysis and protein–protein interaction (PPI) network analysis were also conducted. Hub genes and highly correlated clustered genes were identified using Search Tool for the Retrieval of Interacting Genes (STRING) and Cystoscape software.

Results

One thousand four hundred seventy DEGs were identified between DMD and control, with 1281 upregulated and 189 downregulated DEGs. Four hundred and twenty DEGs were found between BMD and control, with 157 upregulated and 263 upregulated DEGs. Fourteen modules with different colors were identified for DMD vs control, and 7 modules with different colors were identified for BMD vs control. Ten hub genes were summarized for DMD and BMD respectively, 5 hub genes were summarized for BMD age, 5 and 3 highly correlated clustered genes were summarized for DMD age and BMD pathology, respectively. In addition, 20 GO enrichments were found to be involved in DMD, 3 GO enrichments were found to be involved in BMD, 3 GO enrichments were found to be involved in BMD age.

Conclusion

In DMD, several hub genes were identified: C3AR1, TLR7, IRF8, FYB and CD33(immune and inflammation associated genes), TYROBP, PLEK, AIF1(actin reorganization associated genes), LAPTM5 and NT5E(cell death and arterial calcification associated genes, respectively). In BMD, a number of hub genes were identified: LOX, ELN, PLEK, IKZF1, CTSK, THBS2, ADAMTS2, COL5A1(extracellular matrix associated genes), BCL2L1 and CDK2(cell cycle associated genes).

ERS Statement on pediatric long term noninvasive respiratory support

Long term noninvasive respiratory support, comprising continuous positive airway pressure (CPAP) and noninvasive ventilation (NIV), in children is expanding worldwide, with increasing complexities of children being considered for this type of ventilator support and expanding indications such as palliative care. There have been improvements in equipment and interfaces. Despite growing experience, there are still gaps in a significant number of areas: there is a lack of validated criteria for CPAP/NIV initiation, optimal follow-up and monitoring; weaning and long term benefits have not been evaluated. Therapeutic education of the caregivers and the patient is of paramount importance, as well as continuous support and assistance, in order to achieve optimal adherence. The preservation or improvement of the quality of life of the patient and caregivers should be a concern for all children treated with long term CPAP/NIV. As NIV is a highly specialised treatment, patients are usually managed by an experienced pediatric multidisciplinary team. This Statement written by experts in the field of pediatric long term CPAP/NIV aims to emphasize on the most recent scientific input and should open up to new perspectives and research areas.

Lessons Learned From Translational Research in Neuromuscular Diseases: Impact on Study Design, Outcome Measures and Managing Expectation

Spinal Muscular Atrophy (SMA) and Duchenne Muscular Dystrophy (DMD), two of the most common, child onset, rare neuromuscular disorders, present a case study for the translation of preclinical research into clinical work. Over the past decade, well-designed clinical trials and innovative methods have led to the approval of several novel therapies for SMA and DMD, with many more in the pipeline. This review discusses several features that must be considered during trial design for neuromuscular diseases, as well as other rare diseases, to maximise the possibility of trial success using historic examples. These features include well-defined inclusion criteria, matching criteria, alternatives to placebo-controlled trials and the selection of trial endpoints. These features will be particularly important in the coming years as the investigation into innovative therapy approaches for neuromuscular diseases continues.

Results of the home mechanical ventilation national program among adults in Chile between 2008 and 2017

Background

Home mechanical ventilation (HMV) is a viable and effective strategy for patients with chronic respiratory failure (CRF). The Chilean Ministry of Health started a program for adults in 2008.

Methods

This study examined the following data from a prospective cohort of patients with CRF admitted to the national HMV program: characteristics, mode of admission, quality of life, time in the program and survival.

Results

A total of 1105 patients were included. The median age was 59 years (44–58). Women accounted for 58.1% of the sample. The average body mass index (BMI) was 34.9 (26–46) kg/m². A total of 76.2% of patients started HMV in the stable chronic mode, while 23.8% initiated HMV in the acute mode. A total of 99 patients were transferred from the children's program. There were 1047 patients on non-invasive ventilation and 58 patients on invasive ventilation. The median baseline PaCO₂ level was 58.2 (52–65) mmHg. The device usage time was 7.3 h/d (5.8–8.8), and the time in HMV was 21.6 (12.2–49.5) months. The diagnoses were COPD (35%), obesity hypoventilation syndrome (OHS; 23.9%), neuromuscular disease (NMD; 16.3%), non-cystic fibrosis bronchiectasis or tuberculosis (non-CF BC or TBC; 8.3%), scoliosis (5.9%) and amyotrophic lateral sclerosis (ALS; 5.24%). The baseline score on the Severe Respiratory Insufficiency questionnaire (SRI) was 47 (± 17.9) points and significantly improved over time. The lowest 1- and 3-year survival rates were observed in the ALS group, and the lowest 9-year survival rate was observed in the non-CF BC or TB and COPD groups. The best survival rates at 9 years were OHS, scoliosis and NMD. In 2017, there were 701 patients in the children's program and 722 in the adult´s program, with a prevalence of 10.4 per 100,000 inhabitants.

Conclusion

The most common diagnoses were COPD and OHS. The best survival was observed in patients with OHS, scoliosis and NMD. The SRI score improved significantly in the follow-up of patients with HMV. The prevalence of HMV was 10.4 per 100,000 inhabitants.

Trial registration This study was approved by and registered at the ethics committee of North Metropolitan Health Service of Santiago, Chile (N° 018/2021).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-021-01764-4.

One in five patients with Duchenne muscular dystrophy dies from other causes than cardiac or respiratory failure

Duchenne muscular dystrophy (DMD) is a severe neuromuscular disorder with increasing life expectancy from late teens to over 30 years of age. The aim of this nationwide study was to explore the prevalence, life expectancy and leading causes of death in patients with DMD in Sweden. Patients with DMD were identified through the National Quality Registry for Neuromuscular Diseases in Sweden, the Swedish Registry of Respiratory Failure, pathology laboratories, neurology and respiratory clinics, and the national network for neuromuscular diseases. Age and cause of death were retrieved from the Cause of Death Registry and cross-checked with medical records. 373 DMD patients born 1970–2019 were identified, of whom 129 patients deceased during the study period. Point prevalence of adult patients with DMD on December 31st 2019 was 3.2 per 100,000 adult males. Birth prevalence was 19.2 per 100,000 male births. Median survival was 29.9 years, the leading cause of death being cardiopulmonary in 79.9% of patients. Non-cardiopulmonary causes of death (20.1% of patients) mainly pertained to injury-related pulmonary embolism (1.3 per 1000 person-years), gastrointestinal complications (1.0 per 1000 person-years), stroke (0.6 per 1000 person-years) and unnatural deaths (1.6 per 1000 person-years). Death from non-cardiopulmonary causes occurred at younger ages (mean 21.0 years, SD 8.2; p = 0.004). Age at loss of independent ambulation did not have significant impact on overall survival (p = 0.26). We found that non-cardiopulmonary causes contribute to higher mortality among younger patients with DMD. We present novel epidemiological data on the increasing population of adult patients with DMD.

Long-Term Safety and Efficacy Data of Golodirsen in Ambulatory Patients with Duchenne Muscular Dystrophy Amenable to Exon 53 Skipping: A First-in-human, Multicenter, Two-Part, Open-Label, Phase 1/2 Trial

The aim of this Phase 1/2, 2-part, multicenter trial was to report clinical safety and efficacy of long-term golodirsen treatment among ambulatory patients with exon 53 skip-amenable Duchenne muscular dystrophy (DMD). Part 1 was a 12-week, randomized, double-blind, placebo-controlled, dose-titration study followed by 9-week safety review. Part 2 was a 168-week, open-label evaluation of golodirsen 30 mg/kg. Part 1 primary endpoint was safety. Part 2 primary endpoints were dystrophin protein expression and 6-minute walk test (6MWT); secondary endpoints were percent predicted forced vital capacity (FVC%p) and safety. Post hoc ambulation analyses used mutation-matched external natural history controls. All patients from Part 1 (golodirsen, n = 8; placebo, n = 4) plus 13 additional patients entered Part 2; 23 completed the study. Adverse events were generally mild, nonserious, and unrelated to golodirsen, with no safety-related discontinuations or deaths. Golodirsen increased dystrophin protein (16.0-fold; P < 0.001) and exon skipping (28.9-fold; P < 0.001). At 3 years, 6MWT change from baseline was −99.0 m for golodirsen-treated patients versus −181.4 m for external controls (P = 0.067), and loss of ambulation occurred in 9% versus 26% (P = 0.21). FVC%p declined 8.4% over 3 years in golodirsen-treated patients, comparing favorably with literature-reported rates. This study provides evidence for golodirsen biologic activity and long-term safety in a declining DMD population and suggests functional benefit versus external controls. Clinical Trial Registration number: NCT02310906.

Implementation of Hospital-Based Supplemental Duchenne Muscular Dystrophy Newborn Screening (sDMDNBS): A Pathway to Broadening Adoption

Duchenne muscular dystrophy (DMD) is not currently part of mandatory newborn screening, despite the availability of a test since 1975. In the absence of screening, a DMD diagnosis is often not established in patients until 3-6 years of age. During this time, irreversible muscle degeneration takes place, and clinicians agree that the earlier therapy is initiated, the better the long-term outcome. With recent availability of FDA-approved DMD therapies, interest has renewed for adoption by state public health programs, but such implementation is a multiyear process. To speed access to approved therapies, we implemented a unique, hospital-based program offering parents of newborns an optional, supplemental DMD newborn screen (NBS) via a two-tiered approach: utilizing a creatine kinase (CK) enzyme assay coupled with rapid targeted next-generation sequencing (tNGS) for the DMD gene (using a Whole-Exome Sequencing (WES) assay). The tNGS/WES assay integrates the ability to detect both point mutations and large deletion/duplication events. This tiered newborn screening approach allows for the opportunity to improve treatment and outcomes, avoid the diagnostic delays, and diminish healthcare disparities. To implement this screening algorithm through hospitals in a way that would ultimately be acceptable to public health laboratories, we chose an FDA-approved CK-MM immunoassay to avoid the risks of false-negative/-positive results. Because newborn CK values can be affected due to non-DMD-related causes such as birth trauma, a confirmatory repeat CK assay on a later dried blood spot (DBS) collection has been proposed. Difficulties associated with non-routine repeat DBS collection, including the tracking and recall of families, and the potential creation of parental anxiety associated with false-positive results, can be avoided with this algorithm. Whereas a DMD diagnosis is essentially ruled out by the absence of detected DMD sequence abnormalities, a subsequent CK would still be warranted to confirm resolution of the initial elevation, and thus the absence of non-DMD muscular dystrophy or other pathologies. To date, we have screened over 1500 newborns (uptake rate of ~80%) by a CK-MM assay, and reflexed DMD tNGS in 29 of those babies. We expect the experience from this screening effort will serve as a model that will allow further expansion to other hospital systems until a universal public health screening is established.

Life Expectancy in Duchenne Muscular Dystrophy: Reproduced Individual Patient Data Meta-analysis

Background and Objectives

Duchenne muscular dystrophy (DMD) is a rare progressive disease that is often diagnosed in early childhood and leads to considerably reduced life expectancy; because of its rarity, research literature and patient numbers are limited. To fully characterize the natural history, it is crucial to obtain appropriate estimates of the life expectancy and mortality rates of patients with DMD.

Methods

A systematic review of the published literature on mortality in DMD up to July 2020 was undertaken, specifically focusing on publications in which Kaplan-Meier (KM) survival curves with age as a timescale were presented. These were digitized, and individual patient data (IPD) were reconstructed. The pooled IPD were analyzed with the KM estimator and parametric survival analysis models. Estimates were also stratified by birth cohort.

Results

Of 1,177 articles identified, 14 publications met the inclusion criteria and provided data on 2,283 patients, of whom 1,049 had died. Median life expectancy was 22.0 years (95% confidence interval [CI] 21.2, 22.4). Analyses stratified by 3 time periods in which patients were born showed markedly increased life expectancy in more recent patient populations; patients born after 1990 have a median life expectancy of 28.1 years (95% CI 25.1, 30.3).

Discussion

This article presents a full overview of mortality across the lifetime of a patient with DMD and highlights recent improvements in survival. In the absence of large-scale prospective cohort studies or trials reporting mortality data for patients with DMD, extraction of IPD from the literature provides a viable alternative to estimating life expectancy for this patient population.

Kidney Function in Patients With Neuromuscular Disease: Creatinine Versus Cystatin C

Background: Accurate measurement of kidney function in patients with neuromuscular disorders is challenging. Cystatin C, a marker not influenced by skeletal muscle degradation, might be of clinical value in these patients.

Methods: We consecutively enrolled 39 patients with neuromuscular disorders. We investigated the association of the eGFR, based on plasma creatinine and Cystatin C, with clinical and biochemical variables associated with kidney function, namely age and galectin-3.

Results: Creatinine-based eGFR was 242 (±80) and Cystatin C-based eGFR was 110 (±23) mL/min/1.73 m². Cystatin C-based eGFR was associated with age (β −0.63 p < 0.0001) and galectin-3 levels (β −0.43 p < 0.01), while creatinine-based eGFR was not (β −0.22 p = 0.20; β −0.28 p = 0.10). Sensitivity analyses in Duchenne and Becker patients revealed the same results: Cystatin C-based eGFR was associated with age (β −0.61 p < 0.01) and galectin-3 levels (β −0.43 p = 0.05), while creatinine-based eGFR was not (β −0.32 p = 0.13; β −0.34 p = 0.14).

Conclusions: These data indicate that estimation of renal function in patients with neuromuscular disorders cannot reliably be achieved with creatinine, while Cystatin C appears a reasonable alternative. Since a large proportion of patients with neuromuscular disorders develops heart failure, and requires heart failure medication, adequate monitoring of renal function is warranted.

Estimating the current and future prevalence of life-limiting conditions in children in England

BACKGROUND

Previous studies showed increasing number of children with a life-limiting or life-threatening condition who may benefit from input from pediatric palliative care services.

AIM

To estimate the current prevalence of children with a life-limiting condition and to model future prevalence of this population.

DESIGN

Observational study using national inpatient hospital data. A population-based approach utilizing ethnic specific population projections was used to estimate future prevalence.

SETTING/PARTICIPANTS

All children aged 0-19 years with a life-limiting condition diagnostic code recorded in Hospital Episodes Statistics data in England from 2000/01 to 2017/18.

RESULTS

Data on 4,543,386 hospital episodes for 359,634 individuals were included. The prevalence of children with a life-limiting condition rose from 26.7 per 10,000 (95%CI 26.5-27.0) in 2001/02 to 66.4 per 10,000 (95% CI: 66.0-66.8) in 2017/18. Using a more restricted definition of a life-limiting condition reduced the prevalence from 66.4 to 61.1 per 10,000 (95%CI 60.7-61.5) in 2017/18. Highest prevalence was in the under 1-year age group at 226.5 per 10,000 and children with a congenital abnormality had the highest prevalence (27.2 per 10,000 (95%CI: 26.9-27.5)).The prevalence was highest among the most deprived group and in children of Pakistani origin.Predicted future prevalence of life-limiting conditions ranged from 67.0 (95%CI 67.7-66.3) to 84.22 (95%CI 78.66-90.17) per 10,000 by 2030.

CONCLUSIONS

The prevalence of children with a life-limiting or life-threatening condition in England has risen over the last 17 years and is predicted to increase. Future data collections must include the data required to assess the complex health and social care needs of these children.