The Duchenne muscular dystrophy population in Denmark, 1977–2001: prevalence, incidence and survival in relation to the introduction of ventilator use

Prevalence and Classification of Pediatric Neuromuscular Disorders in the Central Region of Portugal

Neuromuscular disorders are a group of rare heterogenous diseases with profound impact on quality of life, for which overall pediatric prevalence has rarely been reported. The purpose of this study was to determine the point prevalence of pediatric neuromuscular disorders and its subcategories in the central region of Portugal. Retrospective case identification was carried out in children with neuromuscular disorders seen between 1998 and 2020 from multiple data sources. Demographics, clinical and molecular diagnoses were registered. On January 1, 2020, the point overall prevalence in the population <18 years of age was 41.20/100 000 (95% confidence interval 34.51-49.19) for all neuromuscular disorders. The main case proportion were genetic disorders (95.7%). We found a relatively higher occurrence of limb-girdle muscular dystrophies, congenital myopathies, and spinal muscular atrophy and a slightly lower occurrence of Duchenne muscular dystrophy, hereditary spastic paraparesis, and acquired neuropathies compared to previous studies in other countries. Molecular confirmation was available in 69.5% of pediatric neuromuscular patients in our cohort.Total prevalence is high in comparison with the data reported in the only previous study on the prevalence of pediatric neuromuscular disorders in our country. Our high definitive diagnostic rate underscores the importance of advances in investigative genetic techniques, particularly new sequencing technologies, in the diagnostic workup of neuromuscular patients.

[Non-invasive Mechanical Ventilation in Acute Respiratory Failure. Clinical Practice Guidelines - on behalf of the German Society of Pneumology and Ventilatory Medicine]

The guideline update outlines the advantages as well as the limitations of NIV in the treatment of acute respiratory failure in daily clinical practice and in different indications.Non-invasive ventilation (NIV) has a high value in therapy of hypercapnic acute respiratory failure, as it significantly reduces the length of ICU stay and hospitalization as well as mortality.Patients with cardiopulmonary edema and acute respiratory failure should be treated with continuous positive airway pressure (CPAP) and oxygen in addition to necessary cardiological interventions. This should be done already prehospital and in the emergency department.In case of other forms of acute hypoxaemic respiratory failure with only mild or moderately disturbed gas exchange (PaO2/FiO2 > 150 mmHg) there is no significant advantage or disadvantage compared to high flow nasal oxygen (HFNO). In severe forms of ARDS NIV is associated with high rates of treatment failure and mortality, especially in cases with NIV-failure and delayed intubation.NIV should be used for preoxygenation before intubation. In patients at risk, NIV is recommended to reduce extubation failure. In the weaning process from invasive ventilation NIV essentially reduces the risk of reintubation in hypercapnic patients. NIV is regarded useful within palliative care for reduction of dyspnea and improving quality of life, but here in concurrence to HFNO, which is regarded as more comfortable. Meanwhile NIV is also recommended in prehospital setting, especially in hypercapnic respiratory failure and pulmonary edema.With appropriate monitoring in an intensive care unit NIV can also be successfully applied in pediatric patients with acute respiratory insufficiency.

Burden of Disease of Duchenne Muscular Dystrophy in Denmark - A National Register-Based Study of Individuals with Duchenne Muscular Dystrophy and their Closest Relatives

Background

Duchenne Muscular Dystrophy (DMD) is a progressive genetic disease with a prevalence of 1 per 3,600-6,000 male births. Individuals with DMD are typically diagnosed at age 4-7 years; median survival is 30 years. They require multidisciplinary care, personal assistance, and often special education.

Objective

The aim was to assess the burden of disease in DMD in Denmark. This includes incidence, prevalence, use of healthcare services, labour market participation, educational outcomes, and overall attributable costs due to DMD. Impact on the closest relatives (siblings and parents) was also investigated.

Methods

The comprehensive Danish national health and administrative registers were used to assess the burden of disease following individuals with DMD and closest relatives from five years before, and up to 20 years after DMD diagnosis. Individuals with DMD (and relatives) from 1994-2021 were included. All outcomes were compared to matched control groups without the disease drawn from the Danish population.

Results

213 unique individuals with DMD were identified. They had lower grades in school, required more special education and more healthcare and home care compared to their control group. The extra costs of special education summed to EUR 180,900 over the course of 11 years elementary school. They had an annual average productivity loss of EUR 20,200 between the age of 18 to 30. The extra healthcare costs of DMD in the 20 years after diagnosis were estimated to EUR 1,524,000. If an individual with DMD lives to be 30, total extra costs sum to EUR 2,365,800.

Conclusions

Using national register data this study presented detailed results on the burden of disease of DMD, including impact on closest relatives. With 60 additional hospital admissions and 200 extra outpatient contacts in 20 years healthcare costs, but also costs of home care and special education, increases as disease progresses.

Chronic Neuromuscular Respiratory Failure and Home Assisted Ventilation

Chronic respiratory failure is a common, important complication of many types of neuromuscular and chest wall disorders. While the pathophysiology of each disease may be different, these disorders can variably affect all muscles involved in breathing, including inspiratory, expiratory, and bulbar muscles, ultimately leading to chronic respiratory failure and hypoventilation. The use of home assisted ventilation through noninvasive interfaces aims to improve the symptoms of hypoventilation, improve sleep quality, and, when possible, improve mortality. An increasing variety of interfaces has allowed for improved comfort and compliance. In a minority of scenarios, noninvasive ventilation is either not appropriate or no longer effective due to disease progression, and a transition to tracheal ventilation should be considered.

Incidence of Duchenne muscular dystrophy in the modern era; an Australian study

Duchenne muscular dystrophy (DMD), an X-linked recessive condition is maternally inherited in two-thirds of affected boys. It is important to establish carrier status of female relatives to restore reproductive confidence for non-carriers and facilitate reproductive options and cardiac surveillance for carriers. This study investigates disease incidence within an Australian model of cascade screening and evolving genetic diagnostic technologies. A retrospective population-based cohort study of all genetically and/or histopathologically confirmed males with DMD, born in New South Wales and the Australian Capital Territory was undertaken from 2002-2012. Cases were identified using state-wide molecular laboratory and clinical databases. The annual disease incidence and "theoretically" preventable cases were extrapolated over the study period. Proband genotype/phenotype, pedigree analysis, carrier-risk and extent of cascade screening were also determined. The cumulative incidence of disease was 19.7 per 100,000 male live births and 1 in 5076 live born males were diagnosed with DMD. Differences in disease incidence were not statistically different when compared between 2002-2007 and 2008-2012 (incidence rate ratio = 1.13, 95% CI 0.76-1.69, p = 0.52). The incidence rate ratio of theoretically preventable cases did not significantly change between 2002-2007 and 2008-2012 (incidence rate ratio = 2.07, 95% CI 0.58-9.21, p = 0.23). Current diagnostic and cascade screening models have limitations in their impact on disease incidence, due to a spectrum of logistical, patient and condition related factors. Innovative approaches to reduce DMD incidence may be better achieved by preconception or early pregnancy carrier screening, prenatal exome sequencing and newborn screening.

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.

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.

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.

Ventilatory support at home for children: A joint position paper from the Thoracic Society of Australia and New Zealand/Australasian Sleep Association

The goal of this position paper on ventilatory support at home for children is to provide expert consensus from Australia and New Zealand on optimal care for children requiring ventilatory support at home, both non-invasive and invasive. It was compiled by members of the Thoracic Society of Australia and New Zealand (TSANZ) and the Australasian Sleep Association (ASA). This document provides recommendations to support the development of improved services for Australian and New Zealand children who require long-term ventilatory support. Issues relevant to providers of equipment and areas of research need are highlighted.

Comparison of Long-term Ambulatory Function in Patients with Duchenne Muscular Dystrophy Treated with Eteplirsen and Matched Natural History Controls

Background:

Duchenne muscular dystrophy (DMD) is a rare, X-linked, fatal, degenerative neuromuscular disease caused by DMD gene mutations. A relationship between exon skipping and dystrophin production in exon 51-amenable patients treated with eteplirsen (EXONDYS 51^®) is established. Once-weekly eteplirsen significantly increased dystrophin, with slower decline in ambulatory function compared to baseline. Long-term treatment with eteplirsen leads to accumulation of dystrophin over time and observed functional benefits in patients with DMD.

Objective:

Compare long-term ambulatory function in eteplirsen-treated patients versus controls.

Methods:

Study 201/202 included 12 eteplirsen-treated patients assessed twice/year for ambulatory function over 4 years. Ambulatory evaluations (6-minute walk test [6MWT], loss of ambulation, and North Star Ambulatory Assessment [NSAA]) were compared with matched controls from Italian Telethon and Leuven registries.

Results:

At Years 3 and 4, eteplirsen-treated patients demonstrated markedly greater mean 6MWT than controls (difference in change from baseline of 132 m [95%CI (29, 235), p = 0.015] at Year 3 and 159 m [95%CI (66, 253), p = 0.002] at Year 4). At Year 4, a significantly greater proportion of eteplirsen-treated patients were still ambulant versus controls (10/12 vs 3/11; p = 0.020). At Year 3, eteplirsen-treated patients demonstrated milder NSAA decline versus controls (difference in change from baseline of 2.6, 95%CI [-6, 11]), however, the difference was not statistically significant; Year 4 control NSAA data were not available.

Conclusion:

In this retrospective matched control study, eteplirsen treatment resulted in attenuation of ambulatory decline over a 4-year observation period, supporting long-term benefit in patients with DMD.

Duchenne and Becker Muscular Dystrophies' Prevalence in MD STARnet Surveillance Sites: An Examination of Racial and Ethnic Differences

INTRODUCTION

Previous studies indicated variability in the prevalence of Duchenne and Becker muscular dystrophies (DBMD) by racial/ethnic groups. The Centers for Disease Control and Prevention's (CDC) Muscular Dystrophy Surveillance, Tracking, and Research network (MD STARnet) conducts muscular dystrophy surveillance in multiple geographic areas of the USA and continues to enroll new cases. This provides an opportunity to continue investigating differences in DBMD prevalence by race and ethnicity and to compare the impact of using varying approaches for estimating prevalence.

OBJECTIVE

To estimate overall and race/ethnicity-specific prevalence of DBMD among males aged 5-9 years and compare the performance of three prevalence estimation methods.

METHODS

The overall and race/ethnicity-specific 5-year period prevalence rates were estimated with MD STARnet data using three methods. Method 1 used the median of 5-year prevalence, and methods 2 and 3 calculated prevalence directly with different birth cohorts. To compare prevalence between racial/ethnic groups, Poisson modeling was used to estimate prevalence ratios (PRs) with non-Hispanic (NH) whites as the referent group. Comparison between methods was also conducted.

RESULTS

In the final population-based sample of 1,164 DBMD males, the overall 5-year prevalence for DBMD among 5-9 years of age ranged from 1.92 to 2.48 per 10,000 males, 0.74-1.26 for NH blacks, 1.78-2.26 for NH whites, 2.24-4.02 for Hispanics, and 0.61-1.83 for NH American Indian or Alaska Native and Asian or Native Hawaiian or Pacific Islander (AIAN/API). The PRs for NH blacks/NH whites, Hispanics/NH whites, and NH AIAN/API/NH whites were 0.46 (95% CI: 0.36-0.59), 1.37 (1.17-1.61), and 0.61 (0.40-0.93), respectively.

CONCLUSIONS

In males aged 5-9 years, compared to the prevalence of DBMD in NH whites, prevalence in NH blacks and NH AIAN/API was lower and higher in Hispanics. All methods produced similar prevalence estimates; however, method 1 produced narrower confidence intervals and method 2 produced fewer zero prevalence estimates than the other two methods.

Liberation and mortality outcomes in pediatric long-term ventilation: A qualitative systematic review

OBJECTIVE

To provide a systematic review of liberation from positive pressure ventilation and mortality of children with chronic respiratory failure who used long-term invasive and noninvasive ventilation (LTV).

METHODS

Papers published from 1980 to 2018 were identified using Pubmed MEDLINE, Ovid MEDLINE, Embase, and Cochrane databases. Search results were limited to English-language papers with (a) patients less than 22 years at initiation, (b) patients who used invasive ventilation (IV) via tracheostomy or noninvasive ventilation (NIV), and (c) data on mortality or liberation from LTV. Data were presented using descriptive statistics; changes in outcomes over time were explored using linear regression. Follow-up variability, cohort heterogeneity, and insufficient data precluded combining data to estimate incidences or rates.

RESULTS

One hundred and thirty papers with 12 704 patients were included. The median number of patients was 37 (interquartile range [IQR] 17-74, range 6-3802). Twenty-five percent of patients were initiated on IV; 75% on NIV. The maximum follow-up ranged from 0.5 to 31.8 years (median 8.8 years). The median proportion of patients liberated in these papers was 3% (IQR 0%-21%). The median proportion of mortality was 18% (IQR 8%-27%). Proportions of liberation and mortality did not significantly change over time. Progression of underlying disease (44%), respiratory illness (19%), and LTV accident (11%) were the most common causes of death.

CONCLUSIONS

These papers collectively show most patients survive for many years using LTV; in many subgroups, death is a more common outcome than liberation. However, the limitations of these papers preclude robust prognostication.

The effects of non-invasive mechanical ventilation on cardiac autonomic dysfunction in spinal muscular atrophy

In patients with spinal muscular atrophy (SMA), obstructive sleep apnea syndrome (OSAS) constitutes an important cause of cardiovascular morbidity and mortality. We investigated heart rate variability (HRV) to evaluate the effects of non-invasive mechanical ventilation on cardiac autonomic dysfunction in patients with SMA and OSAS. Six patients with SMA (type 1 and 2) and six age- and sex-matched healthy children were consecutively enrolled. A whole-night diagnostic polysomnography was performed, and SMA patients with OSAS were given non-invasive mechanical ventilation therapy. HRV analysis was performed on the basis of whole-night electrocardiography recordings via a computer-base program. Apnea-hypopnea index (AHI) was 9.2 ± 6.2/hr in SMA patients, while it was 0.4 ± 0.5/hr in controls (p = 0.036). All SMA patients had OSAS, while none of the controls had OSAS (p = 0.012). Mean percentage of successive R wave of QRS complex (R-R) intervals>50 ms was significantly lower in SMA patients than those in controls (p = 0.031). Significant correlations were found between AHI and high-frequency power, low/high-frequency ratio in wakefulness and in sleep (p<0.05). Repeated HRV analysis in SMA patients following OSAS therapy showed significant reductions in average R-R duration (p = 0.028) and percentage of successive R-R intervals>50 ms (p = 0.043). Our study demonstrates the beneficial effects of non-invasive mechanical ventilation on cardiac autonomic dysfunction in SMA patients with OSAS.

The impact of long-term ventilator-use on health-related quality of life and the mental health of children with neuromuscular diseases and their families: need for a revised perspective?

Background

Life extension by medical interventions and health-related quality of life (HRQOL) are sometimes conflicting aspects of medical care. Long-term ventilation in children with neuromuscular disease is a well-established life-extending procedure and often at the center of this conflict. HRQOL and the mental health of affected children and their families become even more important in respect to emerging therapies in neuromuscular diseases with longer life-expectancy of treated patients and considerable costs of medical treatment.

Methods

We performed a questionnaire survey in a total of forty-three families of children with neuromuscular disease treated in the University Medical Center Hamburg-Eppendorf and the Children’s Hospital Altona. We evaluated self- and proxy-reported HRQOL and mental health outcomes of affected children and their parents using validated and age-appropriate instruments.

Results

Compared to normative data, children with neuromuscular diseases and their families experienced a lower HRQOL and mental health. However, there was no additional negative influence on the overall HRQOL by ventilator use.

Conclusions

As ventilator use was not responsible for the reduction of HRQOL and mental health our data contributes an important aspect to the discussion about life-prolonging procedures, in particular mechanical ventilation, in severly disabled patients.

Global epidemiology of Duchenne muscular dystrophy: an updated systematic review and meta-analysis

Background

Duchenne Muscular Dystrophy (DMD) is a rare disorder caused by mutations in the dystrophin gene. A recent systematic review and meta-analysis of global DMD epidemiology is not available. This study aimed to estimate the global overall and birth prevalence of DMD through an updated systematic review of the literature.

Methods

MEDLINE and EMBASE databases were searched for original research articles on the epidemiology of DMD from inception until 1st October 2019. Studies were included if they were original observational research articles written in English, reporting DMD prevalence and/or incidence along with the number of individuals of the underlying population. The quality of the studies was assessed using a STrengthening the Reporting of OBservational studies in Epidemiology (STROBE) checklist adapted for observational studies on rare diseases. To derive the pooled epidemiological prevalence estimates, a meta-analysis was performed using random-effects logistic models for overall and birth prevalence and within two different underlying populations (i.e. all individuals and in males only), separately. Heterogeneity was assessed using Cochran’s Q-test along with its derived measure of inconsistency I².

Results

A total of 44 studies reporting the global epidemiology of DMD were included in the systematic review and only 40 were included in the meta-analysis. The pooled global DMD prevalence was 7.1 cases (95% CI: 5.0–10.1) per 100,000 males and 2.8 cases (95% CI: 1.6–4.6) per 100,000 in the general population, while the pooled global DMD birth prevalence was 19.8 (95% CI:16.6–23.6) per 100,000 live male births. A very high between-study heterogeneity was found for each epidemiological outcome and for all underlying populations (I² > 90%). The test for funnel plot asymmetry suggested the absence of publication bias. Of the 44 studies included in this systematic review, 36 (81.8%) were assessed as being of medium and 8 (18.2%) of low quality, while no study was assessed as being of high quality.

Conclusions

Generating epidemiological evidence on DMD is fundamental to support public health decision-making. The high heterogeneity and the lack of high quality studies highlights the need to conduct better quality studies on rare diseases.

Molecular and Clinical Characteristics of a National Cohort of Paediatric Duchenne Muscular Dystrophy Patients in Norway

BACKGROUND

As new gene-related treatment options for Duchenne muscular dystrophy (DMD) are being developed, precise information about the patients' genetic diagnosis and knowledge about the diversities of natural history in DMD is vital.

OBJECTIVE

To obtain detailed insight into the genetic and clinical characteristics of paediatric DMD in Norway.

METHODS

94 boys with DMD, aged 0-18 years, were identified over a period of 3.5 years, yielding a national prevalence of 13.5×10-5 boys. 73 boys (78%) were recruited to full genetic and clinical or limited (genetic only) evaluation.

RESULTS

Molecular analysis disclosed 64% deletions, 18% duplications and 18% point mutations. The mean age of diagnosis was 3.9±2.0 years. 78% were treated with glucocorticoids from age 5.8±1.5 years. 23 boys (35%) had lost ambulation at an age of 10.7±2.0 years. 17% were treated for left ventricular dysfunction from age 12.1±3.0 years and 12% had received night-time non-invasive positive pressure ventilation from age 13.0±2.5 years.

CONCLUSIONS

The distribution of mutation types and sites was similar to previous studies but with more duplications and fewer point mutations. Any genotype-phenotype correlations were not uncovered. The boys were diagnosed early but there is still diagnostic delay among boys presenting with late motor development. Glucocorticoid treatment was widespread, especially among the younger boys. The clinical results of this comprehensive nationwide study highlight the large variability of disease progression in DMD.

A hospital based epidemiological study of genetically determined muscle disease in south western Norway

We determined the prevalence of genetically determined neuromuscular diseases in adult Norwegian patients from Hordaland County. We identified patients using International Classification of Disease codes registered in our hospital database and reviewed patient notes to ensure diagnostic accuracy. To ensure maximal ascertainment, we screened both inpatient and outpatient contacts from two 5-year periods 01.01.2005 to 31.12.2009 and 01.01.2008 to 01.01.2013, and used the second data set to define prevalence. Myotonic dystrophy was the commonest adult muscle disorder with a minimum prevalence of 11.84/100,000 followed by facioscapulohumeral muscular dystrophy at 6.42/100,000. Genetically confirmed limb-girdle muscular dystrophies had a prevalence of 4.2/100,000 with CAPN3 mutations being the commonest followed by mutations in ANO5 and FKRP. Becker muscular dystrophy was rare (0.4/100,000). For the purposes of comparison, we also ascertained adults with spinal muscular atrophy (SMA) and found a prevalence of 4.42/100,000. The impact of neuromuscular disease is enormous both for the patient and for society. Progressive weakness and increasing dependency together with pulmonary and cardiac complications require specialised, multidisciplinary follow up. The provision of such care places substantial demands on health service resources. Thus, precise understanding of both type of neuromuscular disease and numbers of patients is essential in order to manage individuals appropriately and plan future health service needs.

Non-invasive Ventilation in Children With Neuromuscular Disease

The respiratory muscles are rarely spared in children with neuromuscular diseases (NMD) which puts them at risk of alveolar hypoventilation. The role of non-invasive ventilation (NIV) is then to assist or "replace" the weakened respiratory muscles in order to correct alveolar hypoventilation by maintaining a sufficient tidal volume and minute ventilation. As breathing is physiologically less efficient during sleep, NIV will be initially used at night but, with the progression of respiratory muscle weakness, NIV can be extended during daytime, preferentially by means of a mouthpiece in order to allow speech and eating. Although children with NMD represent the largest group of children requiring long term NIV, there is a lack of validated criteria to start NIV. There is an agreement to start long term NIV in case of isolated nocturnal hypoventilation, before the appearance of daytime hypercapnia, and/or in case of acute respiratory failure requiring any type of ventilatory support. NIV is associated with a correction in night- and daytime gas exchange, an increase in sleep efficiency and an increase in survival. NIV and/or intermittent positive pressure breathing (IPPB) have been shown to prevent thoracic deformities and consequent thoracic and lung hypoplasia in young children with NMD. NIV should be performed with a life support ventilator appropriate for the child's weight, with adequate alarms, and an integrated (±additional) battery. Humidification is recommended to improve respiratory comfort and prevent drying of bronchial secretions. A nasal interface (or nasal canula) is the preferred interface, a nasobuccal interface can be used with caution in case of mouth breathing. The efficacy of NIV should be assessed on the correction of alveolar ventilation. Patient ventilator synchrony and the absence of leaks can be assessed on a sleep study with NIV or on the analysis of the ventilator's in-built software. The ventilator settings and the interface should be adapted to the child's growth and progression of respiratory muscle weakness. NIV should be associated with an efficient clearance of bronchial secretions by a specific program on the ventilator, IPPB, or mechanical insufflation-exsufflation. Finally, these children should be managed by an expert pediatric multi-disciplinary team.

Respiratory Involvement in Patients with Neuromuscular Diseases: A Narrative Review

Respiratory muscle weakness is a major cause of morbidity and mortality in patients with neuromuscular diseases (NMDs). Respiratory involvement in NMDs can manifest broadly, ranging from milder insufficiency that may affect only sleep initially to severe insufficiency that can be life threatening. Patients with neuromuscular diseases exhibit very often sleep-disordered breathing, which is frequently overlooked until symptoms become more severe leading to irreversible respiratory failure necessitating noninvasive ventilation (NIV) or even tracheostomy. Close monitoring of respiratory function and sleep evaluation is currently the standard of care. Early recognition of sleep disturbances and initiation of NIV can improve the quality of life and prolong survival. This review discusses the respiratory impairment during sleep in patients with NMDs, the diagnostic tools available for early recognition of sleep-disordered breathing and the therapeutic options available for overall respiratory management of patients with NMDs.

Palliative care services in families of males with muscular dystrophy: Data from MD STARnet

Introduction

Information on use of palliative care services among individuals with Duchenne and Becker muscular dystrophy is scant despite the clearly documented need.

Methods

We examined associations between uptake of palliative care services by 233 males with Duchenne and Becker muscular dystrophy aged 12 and older for both caregiver and affected male characteristics using the Muscular Dystrophy Surveillance Tracking and Research Network baseline interview.

Results

Ninety-one percent of caregivers (213/233) used at least one palliative care service. Case management had the highest frequency of use (59%). Use of palliative care was more frequently associated with the characteristics of affected males, as were some individual palliative care services. Utilization of six individual services differed among Muscular Dystrophy Surveillance Tracking and Research Network sites. While research suggests that pain is a frequent problem in Duchenne and Becker muscular dystrophy, only 12.5% reported use of pain management services.

Discussion

Although palliative care use among families of males with Duchenne and Becker muscular dystrophy is high overall, there is much variability in use of individual services. Use of palliative care is driven by disease experience in the affected male. Many of the care recommendations for these individuals highlight the importance for early involvement of palliative care professionals.

A new era in the management of Duchenne muscular dystrophy

The management of Duchenne muscular dystrophy (DMD) has changed considerably over the last few decades. Standards of care have recently been updated, based on systematic reviews of the literature and structured, case-based consensus discussions of experts. Besides addressing muscular function, these recommendations cover most areas of organ involvement and psychosocial issues. Studies employing animal models investigating basic disease mechanisms have increased considerably. Development of valid functional outcome measures enabled high-evidence, clinical trials in males with DMD. Stop codon readthrough with ataluren has revealed some effect in patients with moderate disability and has been approved for males with suitable mutations who are still ambulant. Exon 51 skipping with eteplirsen demonstrated a structural and functional effect in a small group of patients and received restricted approval in the USA. Further trials investigating a broad range of mechanisms are underway. However, much more work is needed to develop more active treatments that stop disease progression. Likewise, the distribution of complex and expensive therapies to underprivileged patients and those in poorer regions must be improved. WHAT THIS PAPER ADDS: Updated standards of care covering most clinical aspects of Duchenne muscular dystrophy (DMD) are available. Adequately controlled clinical trials have allowed initial approval of disease-modifying drugs for small groups of patients. Scientific, economic, and political efforts are needed to make effective therapies available more quickly. Effective therapies should be made available more quickly to patients in low-income regions.

Respiratory Management of the Patient With Duchenne Muscular Dystrophy

In 2010, Care Considerations for Duchenne Muscular Dystrophy, sponsored by the Centers for Disease Control and Prevention, was published in Lancet Neurology, and in 2018, these guidelines were updated. Since the publication of the first set of guidelines, survival of individuals with Duchenne muscular dystrophy has increased. With contemporary medical management, survival often extends into the fourth decade of life and beyond. Effective transition of respiratory care from pediatric to adult medicine is vital to optimize patient safety, prognosis, and quality of life. With genetic and other emerging drug therapies in development, standardization of care is necessary to accurately assess treatment effects in clinical trials. This revision of respiratory recommendations preserves a fundamental strength of the original guidelines: namely, reliance on a limited number of respiratory tests to guide patient assessment and management. A progressive therapeutic strategy is presented that includes lung volume recruitment, assisted coughing, and assisted ventilation (initially nocturnally, with the subsequent addition of daytime ventilation for progressive respiratory failure). This revision also stresses the need for serial monitoring of respiratory muscle strength to characterize an individual's respiratory phenotype of severity as well as provide baseline assessments for clinical trials. Clinical controversies and emerging areas are included.

The role of sleep diagnostics and non-invasive ventilation in children with spinal muscular atrophy

Spinal muscular atrophy (SMA) is a degenerative motor neurone disorder causing progressive muscular weakness. Without assisted ventilation or novel therapies, most children with SMA type 1 die before the second year of life due to respiratory failure as the respiratory muscles and bulbar function are severely affected. Active respiratory treatment (mechanically assisted cough, invasive or non-invasive ventilation) has improved survival significantly in recent decades, but often at the cost of becoming ventilator dependent. The advent of a new oligonucleotide based therapy (Nusinersen) has created new optimism for improving motor function. However, the long-term effect on respiratory function is unclear and non-invasive respiratory support will remain an important part of medical management in patients with SMA. This review summarises the existing knowledge about sleep-disordered breathing and respiratory failure in patients with SMA, especially type 1, as well as the evidence of improved outcome and survival in patients treated with non-invasive or invasive ventilation. Practical considerations and ethical concerns are delineated with discussion on how these may be affected by the advent of new therapies such as Nusinersen.

Consensus on the diagnosis, treatment and follow-up of patients with Duchenne muscular dystrophy

INTRODUCTION

Duchenne muscular dystrophy (DMD) is the most common myopathy in children, with a worldwide prevalence of approximately 0.5 cases per 10,000 male births. It is characterised by a progressive muscular weakness manifesting in early childhood, with the subsequent appearance of musculoskeletal, respiratory, and cardiac complications, causing disability, dependence, and premature death. Currently, DMD is mainly managed with multidisciplinary symptomatic treatment, with favourable results in terms of the progression of the disease. It is therefore crucial to establish clear, up-to-date guidelines enabling early detection, appropriate treatment, and monitoring of possible complications.

DEVELOPMENT

We performed a literature search of the main biomedical databases for articles published in the last 10years in order to obtain an overview of the issues addressed by current guidelines and to identify relevant issues for which no consensus has yet been established. The degree of evidence and level of recommendation of the information obtained were classified and ordered according to the criteria of the American Academy of Neurology.

CONCLUSIONS

DMD management should be multidisciplinary and adapted to the patient's profile and the stage of clinical progression. In addition to corticotherapy, treatment targeting gastrointestinal, respiratory, cardiac, and orthopaedic problems, as well as physiotherapy, should be provided with a view to improving patients' quality of life. Genetic studies play a key role in the management of the disease, both in detecting cases and potential carriers and in characterising the mutation involved and developing new therapies.

Airway clearance techniques in neuromuscular disorders: A state of the art review

This is a unique state of the art review written by a group of 21 international recognized experts in the field that gathered during a meeting organized by the European Neuromuscular Centre (ENMC) in Naarden, March 2017. It systematically reports the entire evidence base for airway clearance techniques (ACTs) in both adults and children with neuromuscular disorders (NMD). We not only report randomised controlled trials, which in other systematic reviews conclude that there is a lack of evidence base to give an opinion, but also include case series and retrospective reviews of practice. For this review, we have classified ACTs as either proximal (cough augmentation) or peripheral (secretion mobilization). The review presents descriptions; standard definitions; the supporting evidence for and limitations of proximal and peripheral ACTs that are used in patients with NMD; as well as providing recommendations for objective measurements of efficacy, specifically for proximal ACTs. This state of the art review also highlights how ACTs may be adapted or modified for specific contexts (e.g. in people with bulbar insufficiency; children and infants) and recommends when and how each technique should be applied.

Diagnosis and management of Duchenne muscular dystrophy, part 2: respiratory, cardiac, bone health, and orthopaedic management

A coordinated, multidisciplinary approach to care is essential for optimum management of the primary manifestations and secondary complications of Duchenne muscular dystrophy (DMD). Contemporary care has been shaped by the availability of more sensitive diagnostic techniques and the earlier use of therapeutic interventions, which have the potential to improve patients' duration and quality of life. In part 2 of this update of the DMD care considerations, we present the latest recommendations for respiratory, cardiac, bone health and osteoporosis, and orthopaedic and surgical management for boys and men with DMD. Additionally, we provide guidance on cardiac management for female carriers of a disease-causing mutation. The new care considerations acknowledge the effects of long-term glucocorticoid use on the natural history of DMD, and the need for care guidance across the lifespan as patients live longer. The management of DMD looks set to change substantially as new genetic and molecular therapies become available.

Left bundle branch block in Duchenne muscular dystrophy: Prevalence, genetic relationship and prognosis

Background

Duchenne muscular dystrophy (DMD) is an inherited myogenic disorder due to mutations in the dystrophin gene on chromosome Xp21.1. We designed this study to determine the prevalence of left bundle branch block (LBBB), whether there is a relationship between LBBB and genetic pattern, and to assess predictive factors for acute cardiac events and mortality in adult DMD patients.

Methods

We reviewed the charts of DMD followed at the Home Mechanical Ventilation Unit of the Raymond Poincare University Hospital.

Results

A total of 121 patients, aged from 18 to 41 years have been included in our study. Median vital capacity (VC) was 12% [7; 19.5] of predicted. Almost all patients were on home mechanical ventilation (95%). LBBB was present in 15 patients (13%); among them, 10 disclosed exonic deletions. After a median follow up of 6 years, 21 patients (17%) experienced acute heart failure (AHF), 7 patients (6%) supraventricular arrhythmia, 3 patients (2.4%) ventricular tachycardia, 4 patients (3%) significant electrical disturbances. LBBB was significantly associated with cardiac events (OR = 12.7; 95%CI [3.78–42.7]; p <0.0001) and mortality (OR = 4.4; 95%CI [1.44–13.7]; p 0.009). Presence of residual dystrophin protein was not associated with significant less cardiac events. Age and LVEF were also predictive factors for cardiac events and mortality.

Conclusion

LBBB is relatively frequent in DMD and is a major predictive factor for cardiac events and mortality. Presence of residual dystrophin protein was not associated with a lower incidence of cardiac events.

Mouthpiece ventilation in Duchenne muscular dystrophy: a rescue strategy for noncompliant patients

Objective:

To evaluate mouthpiece ventilation (MPV) in patients with Duchenne muscular dystrophy (DMD) who are noncompliant with noninvasive ventilation (NIV).

Methods:

We evaluated four young patients with DMD who had previously refused to undergo NIV. Each patient was reassessed and encouraged to try MPV.

Results:

The four patients tolerated MPV well and were compliant with NIV at home. MPV proved to be preferable and more comfortable than NIV with any other type of interface. Two of the patients required overnight NIV and eventually agreed to use a nasal mask during the night.

Conclusions:

The advantages of MPV over other types of NIV include fewer speech problems, better appearance, and less impact on the patient, eliminating the risk of skin breakdown, gastric distension, conjunctivitis, and claustrophobia. The use of a mouthpiece interface should be always considered in patients with DMD who need to start NIV, in order to promote a positive approach and a rapid acceptance of NIV. Using MPV during the daytime makes patients feel safe and more likely to use NIV at night. In addition, MPV increases treatment compliance for those who refuse to use other types of interfaces.

The Epidemiology of Neuromuscular Diseases

Neuromuscular disorders as a group are linked by anatomy with significant differences in pathogenetic mechanisms, clinical expression, and time course of disease. Each neuromuscular disease is relatively uncommon, yet causes a significant burden of disease socioeconomically. Epidemiologic studies in different global regions have demonstrated certain neuromuscular diseases have increased incidence and prevalence rates over time. Understanding differences in global epidemiologic trends will aid clinical research and policies focused on prevention of disease. There is a critical need to understand the global impact of neuromuscular diseases using metrics currently established for communicable and noncommunicable diseases.

Ageing with Muscular Disease

BACKGROUND

The demographic development with an ageing population is predicted to be the next global public health challenge. Advances in medicine and the socioeconomic development have reduced mortality and morbidity due to infectious conditions and non-communicable diseases. The increase in longevity will not be restricted to healthy people.

OBJECTIVE

To understand how people with muscular diseases experience ageing.

METHOD

A literature review was conducted using the Matrix Method developed by Garrard (2007). This systematic method was used to identify, describe and interpret studies, irrespective of the methods applied. To avoid the exclusion of important sources, experiences and topics, we chose an integrative approach that accommodates the inclusion of studies with different methodologies. People with MD have gradually extended their life expectancy during the last 30 years. Thus, we reviewed the literature regarding MD and ageing without time limit.

RESULTS

We identified three themes: 1) Slowing down early 2) Accepting lifelong deterioration and 3) Striving for normality.

CONCLUSION

People with MD live in a field of tension between a feeling of autonomy and normality and difficulties coping with reduced physical abilities. Getting older accentuates this tension since the physical strength diminishes and it is harder to maintain autonomy. The bodily challenges may coincide with the end of the rehabilitation people living with MD have received. Seemingly, no age-related rehabilitation is offered, and people living with MD are thus at risk of an unnecessarily passive life.

Study of Duchenne muscular dystrophy long-term survivors aged 40 years and older living in specialized institutions in Japan

The national muscular dystrophy wards database of Japan lists 118 long-term Duchenne muscular dystrophy (DMD) patients who were at least 40 years old as of October 1, 2013. To elucidate the clinical features of DMD patients aged 40 years and older, we obtained gene analysis and muscle biopsy findings, as well as medical condition information. Ninety-four of the registered patients consented to participate, of whom 55 meeting genetic or biochemical criteria confirming DMD were analyzed. The mean age at the time of the study was 43.6 ± 3.0 years, while at the time of independent ambulation loss it was 10.6 ± 1.5 years and at mechanical ventilation introduction it was 24.1 ± 5.5 years. All were receiving continuous ventilation support, 27 with non-invasive positive pressure ventilation and 28 with tracheal intermittent positive pressure ventilation. Thirty-eight were receiving β-blockers or a renin-angiotensin system inhibitor, while 9 were free from those agents. Forty had maintained oral nutrition. The 55 analyzed patients had survived into their 40s by receiving multidisciplinary intervention. Our findings emphasize the need of future studies to investigate disease modifiers and the mechanism of long-term survival. In addition, establishment of a worldwide care standard with focus on quality of life for adult males with DMD is important.

Nutraceuticals and Their Potential to Treat Duchenne Muscular Dystrophy: Separating the Credible from the Conjecture

In recent years, complementary and alternative medicine has become increasingly popular. This trend has not escaped the Duchenne Muscular Dystrophy community with one study showing that 80% of caregivers have provided their Duchenne patients with complementary and alternative medicine in conjunction with their traditional treatments. These statistics are concerning given that many supplements are taken based on purely "anecdotal" evidence. Many nutraceuticals are thought to have anti-inflammatory or anti-oxidant effects. Given that dystrophic pathology is exacerbated by inflammation and oxidative stress these nutraceuticals could have some therapeutic benefit for Duchenne Muscular Dystrophy (DMD). This review gathers and evaluates the peer-reviewed scientific studies that have used nutraceuticals in clinical or pre-clinical trials for DMD and thus separates the credible from the conjecture.

Identifying evidence of cardio-renal syndrome in patients with Duchenne muscular dystrophy using cystatin C

Patients with Duchenne muscular dystrophy (DMD) develop dilated cardiomyopathy and are at risk for kidney injury. Creatinine based estimated glomerular filtration rate (eGFR) is limited by low muscle mass with low serum creatinine levels in DMD. We assessed the relationship between cardiac function, modified Schwartz eGFR and cystatin C eGFR in patients with DMD. Ninety-three patients with DMD were screened for renal dysfunction in an outpatient neuromuscular clinic. Patients with new nephrotoxic medications, recent hospitalization or decompensated heart failure were excluded from the analysis. Eleven (12%) patients had evidence of renal dysfunction identified by cystatin C eGFR, while no patients had renal dysfunction by Schwartz eGFR. There was no significant correlation between cystatin C eGFR and age (r = -0.2, p = 0.11), prednisone dose (r = 0.06, p = 0.89) or deflazacort dose (r = -0.01, p = 0.63). There was a significant correlation between left ventricular ejection fraction and cystatin C GFR among patients with chronic left ventricular dysfunction (r = 0.46, p < 0.01), but not normal function (r = -0.07, p = 0.77). There was no significant correlation between left ventricular ejection fraction and Schwartz eGFR among patients with (r = 0.07, p = 0.59) or without (r = -0.27, p = 0.07) chronic left ventricular dysfunction. Cystatin C eGFR correlates with cardiac dysfunction in patients with DMD, thus providing novel evidence of cardio-renal syndrome in this population. Routine monitoring of renal function is recommended in patients with DMD.

Corticosteroids for the treatment of Duchenne muscular dystrophy

BACKGROUND

Duchenne muscular dystrophy (DMD) is the most common muscular dystrophy of childhood. Untreated, this incurable disease, which has an X-linked recessive inheritance, is characterised by muscle wasting and loss of walking ability, leading to complete wheelchair dependence by 13 years of age. Prolongation of walking is a major aim of treatment. Evidence from randomised controlled trials (RCTs) indicates that corticosteroids significantly improve muscle strength and function in boys with DMD in the short term (six months), and strength at two years (two-year data on function are very limited). Corticosteroids, now part of care recommendations for DMD, are largely in routine use, although questions remain over their ability to prolong walking, when to start treatment, longer-term balance of benefits versus harms, and choice of corticosteroid or regimen.We have extended the scope of this updated review to include comparisons of different corticosteroids and dosing regimens.

OBJECTIVES

To assess the effects of corticosteroids on prolongation of walking ability, muscle strength, functional ability, and quality of life in DMD; to address the question of whether benefit is maintained over the longer term (more than two years); to assess adverse events; and to compare efficacy and adverse effects of different corticosteroid preparations and regimens.

SEARCH METHODS

On 16 February 2016 we searched the Cochrane Neuromuscular Specialised Register, CENTRAL, MEDLINE, EMBASE, CINAHL Plus, and LILACS. We wrote to authors of published studies and other experts. We checked references in identified trials, handsearched journal abstracts, and searched trials registries.

SELECTION CRITERIA

We considered RCTs or quasi-RCTs of corticosteroids (e.g. prednisone, prednisolone, and deflazacort) given for a minimum of three months to patients with a definite DMD diagnosis. We considered comparisons of different corticosteroids, regimens, and corticosteroids versus placebo.

DATA COLLECTION AND ANALYSIS

The review authors followed standard Cochrane methodology.

MAIN RESULTS

We identified 12 studies (667 participants) and two new ongoing studies for inclusion. Six RCTs were newly included at this update and important non-randomised cohort studies have also been published. Some important studies remain unpublished and not all published studies provide complete outcome data.

PRIMARY OUTCOME MEASURE

one two-year deflazacort RCT (n = 28) used prolongation of ambulation as an outcome measure but data were not adequate for drawing conclusions.

SECONDARY OUTCOME MEASURES

meta-analyses showed that corticosteroids (0.75 mg/kg/day prednisone or prednisolone) improved muscle strength and function versus placebo over six months (moderate quality evidence from up to four RCTs). Evidence from single trials showed 0.75 mg/kg/day superior to 0.3 mg/kg/day on most strength and function measures, with little evidence of further benefit at 1.5 mg/kg/day. Improvements were seen in time taken to rise from the floor (Gowers' time), timed walk, four-stair climbing time, ability to lift weights, leg function grade, and forced vital capacity. One new RCT (n = 66), reported better strength, function and quality of life with daily 0.75 mg/kg/day prednisone at 12 months. One RCT (n = 28) showed that deflazacort stabilised muscle strength versus placebo at two years, but timed function test results were too imprecise for conclusions to be drawn.One double-blind RCT (n = 64), largely at low risk of bias, compared daily prednisone (0.75 mg/kg/day) with weekend-only prednisone (5 mg/kg/weekend day), finding no overall difference in muscle strength and function over 12 months (moderate to low quality evidence). Two small RCTs (n = 52) compared daily prednisone 0.75 mg/kg/day with daily deflazacort 0.9 mg/kg/day, but study methods limited our ability to compare muscle strength or function.

ADVERSE EFFECTS

excessive weight gain, behavioural abnormalities, cushingoid appearance, and excessive hair growth were all previously shown to be more common with corticosteroids than placebo; we assessed the quality of evidence (for behavioural changes and weight gain) as moderate. Hair growth and cushingoid features were more frequent at 0.75 mg/kg/day than 0.3 mg/kg/day prednisone. Comparing daily versus weekend-only prednisone, both groups gained weight with no clear difference in body mass index (BMI) or in behavioural changes (low quality evidence for both outcomes, one study); the weekend-only group had a greater linear increase in height. Very low quality evidence suggested less weight gain with deflazacort than with prednisone at 12 months, and no difference in behavioural abnormalities. Data are insufficient to assess the risk of fractures or cataracts for any comparison.Non-randomised studies support RCT evidence in showing improved functional benefit from corticosteroids. These studies suggest sustained benefit for up to 66 months. Adverse effects were common, although generally manageable. According to a large comparative longitudinal study of daily or intermittent (10 days on, 10 days off) corticosteroid for a mean period of four years, a daily regimen prolongs ambulation and improves functional scores over the age of seven, but with a greater frequency of side effects than an intermittent regimen.

AUTHORS' CONCLUSIONS

Moderate quality evidence from RCTs indicates that corticosteroid therapy in DMD improves muscle strength and function in the short term (twelve months), and strength up to two years. On the basis of the evidence available for strength and function outcomes, our confidence in the effect estimate for the efficacy of a 0.75 mg/kg/day dose of prednisone or above is fairly secure. There is no evidence other than from non-randomised trials to establish the effect of corticosteroids on prolongation of walking. In the short term, adverse effects were significantly more common with corticosteroids than placebo, but not clinically severe. A weekend-only prednisone regimen is as effective as daily prednisone in the short term (12 months), according to low to moderate quality evidence from a single trial, with no clear difference in BMI (low quality evidence). Very low quality evidence indicates that deflazacort causes less weight gain than prednisone after a year's treatment. We cannot evaluate long-term benefits and hazards of corticosteroid treatment or intermittent regimens from published RCTs. Non-randomised studies support the conclusions of functional benefits, but also identify clinically significant adverse effects of long-term treatment, and a possible divergence of efficacy in daily and weekend-only regimens in the longer term. These benefits and adverse effects have implications for future research and clinical practice.

Impact of invasive ventilation on survival when non-invasive ventilation is ineffective in patients with Duchenne muscular dystrophy: A prospective cohort

BACKGROUND

Many patients with DMD undergo tracheostomy. Tracheostomy is associated with certain complications, however its effect on prognosis is not known.

METHODS

The relationship between type of mechanical ventilation and survival at 12 years was evaluated in a prospective cohort of patients with Duchenne muscular dystrophy followed in a French reference center for Neuromuscular Diseases. Cox proportional-hazards regressions were used to estimate the hazard ratios associated with risk of switching from non-invasive to invasive ventilation, and with risk of death.

RESULTS

One hundred and fifty patients were included. Initial use of invasive ventilation was associated with an episode of acute respiratory failure (p < 0.0001) and with a severe clinical status (p < 0.05). Risk of death was associated with swallowing disorders (2.51, IC [1.12-5.66], p < 0.03) and cardiac failure (p < 0.05) but not with type of mechanical ventilation.

CONCLUSION

Switching to invasive ventilation is appropriate when non-invasive ventilation is ineffective.

Mutational spectrum of Duchenne muscular dystrophy in Spain: Study of 284 cases

INTRODUCTION

Duchenne muscular dystrophy (DMD) is a severe X-linked recessive neuromuscular disease that affects one in 3500 live-born males. The total absence of dystrophin observed in DMD patients is generally caused by mutations that disrupt the reading frame of the DMD gene, and about 80% of cases harbour deletions or duplications of one or more exons.

METHODS

We reviewed 284 cases of males with a genetic diagnosis of DMD between 2007 and 2014. These patients were selected from 8 Spanish reference hospitals representing most areas of Spain. Multiplex PCR, MLPA, and sequencing were performed to identify mutations.

RESULTS

Most of these DMD patients present large deletions (46.1%) or large duplications (19.7%) in the dystrophin gene. The remaining 34.2% correspond to point mutations, and half of these correspond to nonsense mutations. In this study we identified 23 new mutations in DMD: 7 large deletions and 16 point mutations.

CONCLUSIONS

The algorithm for genetic diagnosis applied by the participating centres is the most appropriate for genotyping patients with DMD. The genetic specificity of different therapies currently being developed emphasises the importance of identifying the mutation appearing in each patient; 38.7% of the cases in this series are eligible to participate in current clinical trials.

Hypoxia-induced cardiac injury in dystrophic mice

Duchenne muscular dystrophy (DMD) is a disease of progressive destruction of striated muscle, resulting in muscle weakness with progressive respiratory and cardiac failure. Respiratory and cardiac disease are the leading causes of death in DMD patients. Previous studies have suggested an important link between cardiac dysfunction and hypoxia in the dystrophic heart; these studies aim to understand the mechanism underlying this connection. Here we demonstrate that anesthetized dystrophic mice display significant mortality following acute exposure to hypoxia. This increased mortality is associated with a significant metabolic acidosis, despite having significantly higher levels of arterial Po2 Chronic hypoxia does not result in mortality, but rather is characterized by marked cardiac fibrosis. Studies in isolated hearts reveal that the contractile function of dystrophic hearts is highly susceptible to short bouts of ischemia, but these hearts tolerate prolonged acidosis better than wild-type hearts, indicating an increased sensitivity of the dystrophic heart to hypoxia. Dystrophic hearts display decreased cardiac efficiency and oxygen extraction. Isolated dystrophic cardiomyocytes and hearts have normal levels of FCCP-induced oxygen consumption, and mitochondrial morphology and content are normal in the dystrophic heart. These studies demonstrate reductions in cardiac efficiency and oxygen extraction of the dystrophic heart. The underlying cause of this reduced oxygen extraction is not clear; however, the current studies suggest that large disruptions of mitochondrial respiratory function or coronary flow regulation are not responsible. This finding is significant, as hypoxia is a common and largely preventable component of DMD that may contribute to the progression of the cardiac disease in DMD patients.

Cardiac phenotype determines survival in Duchenne muscular dystrophy

OBJECTIVE

To identify determinants of survival by comparing cardiopulmonary function in two patient groups: prolonged survivors of Duchenne muscular dystrophy (DMD) versus DMD patients who experienced early death (ED).

METHODS

Retrospective chart review of our DMD patients from 1999 to 2013. Prolonged Survival (PS) was defined as alive and ≥30 years old. Early death (ED) was defined as death at < 30 years old.

EXCLUSION CRITERIA

steroid therapy.

RESULTS

Eleven patients met criteria for PS and 14 patients for ED (mean age ± SD: 34.3 ± 4.3 years vs. 21.7 ± 3.8 years, respectively; P < 0.001). Pulmonary function was better in the ED patients: all PS patients had a vital capacity of 0 ml (n = 11) versus 23% (3/13) of the ED patients (P < 0.001). Thirteen of 14 ED patients and all PS patients received assisted ventilation. Heart function was worse in the ED patients: ejection fraction (EF) was 42.2 ± 14.2% in the PS patients (n = 11) versus 29.2 ± 14.1% in the ED patients (n = 13; P = 0.035). Dilated cardiomyopathy was present in 36% (4/11) of PS patients versus 78% (11/14) of ED patients (P =0.048). Among ED patients, 57% (8/14) died from progressive cardiomyopathy.

CONCLUSION

In our study group, good heart function was a pre-condition for PS and poor heart function was the primary cause of early death. Our results suggest that, when DMD patients are treated with assisted ventilation, heart function is the main determinant of their survival.

Rehabilitative technology use among individuals with Duchenne/Becker muscular dystrophy

PURPOSE

To document use of rehabilitative technology among individuals with Duchenne/Becker muscular dystrophy (DBMD) among sites of the Muscular Dystrophy Surveillance, Tracking, and Research network (MD STARnet).

METHODS

Data from 362 caregivers who participated in the MD STARnet caregiver interview between April 2006 and March 2012 (54.7% response rate) were analyzed to assess the type, frequency and duration of use of assistive technology.

RESULTS

Caregiver reports of technology use by individuals with DBMD across five MD STARnet sites in the US demonstrated significant regional differences in the proportion of individuals who had ever used night splints (36.9%-73.0%), standers (3.1%-22.2%) and scooters (10.7%-54.5%). Among individuals who used night splints 59.7% stopped using them at a mean age of 10.3 years after a mean duration of 2.9 years in spite of the current recommendation to continue using them through the non-ambulatory phase.

DISCUSSION

Results of this comprehensive survey document the frequency of assistive device use by individuals with DBMD in the USA and also provides data on differences across the sites. Further research is needed to understand the reasons for and the impact of these differences on clinical outcomes and health related quality of life of individuals with DBMD.

Health services received by individuals with duchenne/becker muscular dystrophy

INTRODUCTION

Anecdotal reports from families and care providers suggest a wide variation in services received by individuals with Duchenne/Becker muscular dystrophy (DBMD).

METHODS

We documented the type and frequency of health services received by individuals with DBMD using the Muscular Dystrophy Surveillance Tracking and Research Network (MD STARnet) interview data released in June 2012. Interviews with eligible caregivers from 5 sites (Arizona, Colorado, Georgia, Iowa, and western New York) were conducted from April 2007 to March 2012.

RESULTS

Two hundred ninety-six caregivers (66% of those contactable) participated in the interview. There were significant differences among sites in the specialists seen and services received. Concurrence with cardiac recommendations was higher than that with respiratory recommendations.

CONCLUSIONS

The results of this survey support and quantify the anecdotal reports from families and care providers regarding the disparities in services received by individuals with DBMD. It remains to be determined whether these differences affect outcomes.