The myotonic dystrophy experience: a North American cross-sectional study

Living with adult-onset myotonic dystrophy type 1: a scoping review

PURPOSE

To identify the existing literature on experiences of living with adult-onset myotonic dystrophy type 1 (DM1) from people with adult-onset DM1, their caregivers and health care professionals.

MATERIALS AND METHODS

Following the framework of Arksey and O'Malley, a literature search was performed in five databases in October-November 2022. An updated search was conducted in December 2023. Studies were eligible if they reported on experiences related to living with DM1 from people with adult-onset DM1, caregivers or healthcare professionals. Qualitative, quantitative, and mixed method studies were included. Key findings were categorized using the International Classification of Functioning, Disability and Health (ICF) components.

RESULTS

11 out of 1842 studies were included, of which five had a quantitative design, five had a qualitative design and one study had a mixed methods design. The studies reported on multiple experiences of living with adult-onset DM1 from the perspectives of people with the disease and their caregivers. All components of the ICF were reported in the studies; activity and participation and personal factors were the most reported.

CONCLUSION

Adult-onset DM1 is a complex disease with great biopsychosocial impact making it challenging to live with for those diagnosed with DM1 as well as their caregivers.

Expert opinion on mexiletine treatment in adult patients with myotonic dystrophy

In France, mexiletine - a class I antiarrhythmic drug - can be prescribed for the symptomatic treatment of myotonia of the skeletal muscles in adult patients with myotonic dystrophy under a compassionate use programme. Mexiletine is used according to its summary of product characteristics, which describes its use for myotonia treatment in adult patients with non-dystrophic myotonia, a different neuromuscular condition without cardiac involvement. A cardiac assessment is required prior to initiation and throughout treatment due to potential proarrhythmic effects. The presence of conduction system disease, the most common cardiac manifestation of myotonic dystrophy, mandates repeated cardiac evaluations in patients with this condition, and becomes even more important when they are given mexiletine. A group of experts, including three neurologists and five cardiologists from French neuromuscular reference centres, were involved in a task force to develop a treatment algorithm to guide mexiletine use in myotonic dystrophy. The recommendations are based on data from a literature review of the safety of mexiletine-treated patients with myotonic dystrophy, the compassionate use protocol for mexiletine and the personal clinical experience of the experts. The main conclusion of the expert group is that, although existing safety data in mexiletine-treated patients with myotonic dystrophy are reassuring, cardiac assessments should be reinforced in such patients compared with mexiletine-treated patients with non-dystrophic myotonia. This expert opinion to guide mexiletine treatment in patients with myotonic dystrophy should help to reduce the risk of severe adverse events and facilitate interactions between specialists involved in the routine care of patients with myotonic dystrophy.

Clinical features and genetic spectrum of a multicenter Chinese cohort with myotonic dystrophy type 1

BACKGROUND

As the most common subtype of adult muscular dystrophy worldwide, large cohort reports on myotonic dystrophy type I (DM1) in China are still lacking. This study aims to analyze the genetic and clinical characteristics of Chinese Han DM1 patients.

METHODS

Based on the multicenter collaborating effort of the Pan-Yangtze River Delta Alliance for Neuromuscular Disorders, patients with suspected clinical diagnoses of DM1 were genetically confirmed from January 2020 to April 2023. Peak CTG repeats in the DMPK gene were analyzed using triplet repeat-primed PCR (TP-PCR) and flanking PCR. Time-to-event analysis of onset age in females and males was performed. Additionally, detailed clinical features and longitudinal changes from the disease onset in 64 DM1 patients were retrospectively collected and analyzed. The Epworth Sleepiness Scale and Fatigue Severity Scale were used to quantify the severity of daytime sleepiness and fatigue.

RESULTS

Among the 211 genetically confirmed DM1 patients, the mean age at diagnosis was 40.9 ± 12.2 (range: 12-74) with a male-to-female ratio of 124:87. The average size of CTG repeats was 511.3 (range: 92-1945). Among the DM1 patients with comprehensive clinical data (n = 64, mean age 41.0 ± 12.0), the age at onset was significantly earlier in males than in females (4.8 years earlier, p = 0.026). Muscle weakness (92.2%), myotonia (85.9%), and fatigue (73.4%) were the most prevalent clinical features. The predominant involved muscles at onset are hands (weakness or myotonia) (52.6%) and legs (walking disability) (42.1%). Of them, 70.3% of patients had daytime sleepiness, 14.1% had cataract surgery, 7.8% used wheelchairs, 4.7% required ventilatory support, and 1.6% required gastric tubes. Regarding the comorbidities, 4.7% of patients had tumors, 17.2% had diabetes, 23.4% had dyspnea, 28.1% had intermittent insomnia, 43.8% experienced dysphagia, and 25% exhibited cognitive impairment. Chinese patients exhibited smaller size of CTG repeats (468 ± 139) than those reported in Italy (613 ± 623), the US (629 ± 386), and Japan (625 [302, 1047]), and milder phenotypes with less multisystem involvement.

CONCLUSION

The Chinese Han DM1 patients presented milder phenotypes compared to their Caucasian and Japanese counterparts. A male predominance and an early age of onset were identified in male Chinese Han DM1 patients.

Myotonic dystrophy type 1 (Steinert disease): 29 years of experience at a tertiary pediatric hospital

BACKGROUND

Myotonic dystrophy type 1 (DM1) is a multisystemic disorder caused by the expansion of a noncoding triplet repeat.

METHODS

A cross-sectional study was performed to characterize pediatric patients with DM1 followed in a tertiary hospital over the last 29 years, comparing the congenital and the childhood/juvenile-onset forms.

RESULTS

Thirty-seven patients (59.5 % male) were included, with a median age at the latest assessment of 16.8 years and a median follow-up of 7.7 years. Eleven patients were lost to follow-up, and two died. Twenty-five had congenital DM1 (CDM1), and this form had significantly higher triplet repeat length, history of polyhydramnios, lower median age at diagnosis, and first and last assessment. Common symptoms included distal skeletal muscle weakness (75.7 %) and facial involvement (94.6 %), along with dysphonia/dysarthria (73.0 %) and myotonia (73.0 %). Delayed independent ambulation frequency was significantly higher for CDM1 cases. Skeletal deformities affected 54.1 %, with talipes equinovarus and scoliosis occurring exclusively in CDM1 patients. Cognitive deficit was present in 75.7 % of cases. Polysomnograms revealed seven cases of obstructive sleep apnea and two of hypoventilation. Noninvasive ventilation was used in nine cases, and three had recurrent respiratory infections. The cardiovascular system was affected in 21.6 % of cases. Gastrointestinal issues included constipation (24.3 %), feeding difficulties (16.2 %), and cholelithiasis (5.4 %). Cataracts, epilepsy, and diabetes mellitus were reported in two cases each.

CONCLUSION

Our study highlights the diverse spectrum of severity and multiorgan involvement of DM1 in pediatric patients. It underscores the importance of establishing a pediatric-specific standard of care to enhance health outcomes through comprehensive multidisciplinary management.

Myotonic dystrophy type 1: 13 years of experience at a tertiary hospital. Clinical and epidemiological study and genotype-phenotype correlation

INTRODUCTION

The incidence of myotonic dystrophy type 1 (DM1), a disease with great phenotypic variety, in our region is unknown. This study aims to estimate the incidence of DM1 at our hospital (a reference centre in Aragon, Spain) and to identify the characteristics of our population (genotype-phenotype correlation).

METHODS

Retrospective, descriptive study of 459 patients classified according to the number of CTG repeats, as follows: normal (5-35), premutation (36-50), protomutation (51-80), small expansions (81-150), intermediate expansions (151-1000), and large expansions (> 1000). Furthermore, according to clinical phenotype, patients were categorised as unaffected (5-50 CTG repeats), mild form or asymptomatic (51-150), classical form (151-1000), and severe form (> 1000).

RESULTS

The incidence of DM1 was 20.61 cases per million person-years (95% CI, 19.59-21.63). An inverse correlation was observed between the number of CTG repeats and the age at genetic diagnosis (ρ = -0.547; 95% CI, -0.610 to -0.375; P < .001). CTG5 was the most frequent polymorphic allele in healthy individuals. Of all patients with DM1, 28.3% presented the mild or asymptomatic form, 59.1% the classical form, and 12.6% the severe form. Inheritance was maternal in 35.1% of cases, paternal in 59.4%, and uncertain in 5.5%. In mild forms, frontal balding in men was the most prevalent phenotypic trait, as well as myotonia and cataracts, while in the classical form, ptosis, facial weakness, voice and pronunciation alterations, myotonia, and fatigue/sleepiness were most frequent.

CONCLUSIONS

The incidence of DM1 in Aragon is significant. Multidisciplinary study of the phenotype of patients with DM1 is key to early diagnosis and personalised management.

A retrospective study of needs and interventions among patients with myotonic dystrophy type 1 in Denmark referred to rehabilitation in the period 2000-2019

RATIONALE, AIMS AND OBJECTIVES: Myotonic dystrophy type 1 (DM1) is a progressive multisystem disorder that requires a special focus on the delivery of health and rehabilitation. The aim of the study was to identify the needs and interventions in patients with DM1 referred to a national rehabilitation hospital and to illustrate the needs and interventions in relation to predefined subgroups of disease classification.

METHOD

Electronic medical records from the period 2000-2019 of a randomized sample of patients with DM1 (N = 193) were reviewed to identify rehabilitation needs and interventions. The sample was classified into four subgroups of disease classifications. The number of identified needs and interventions were presented as medians and range, and differences between subgroups were illustrated by Kruskal-Wallis one-way analysis of variance. The needs were categorized using the International Classification of Functioning, Disability and Health (ICF).

RESULTS

A total of 2099 needs and 2103 interventions were registered. The most frequent needs were coordination of healthcare services (480) and employment and income (363), while the most frequent interventions were counselling (835) and follow-up (386). Patients with congenital DM1 had the most needs and interventions per person. In relation to the ICF, the most registered needs were environmental factors (880) and activity and participation (848).

CONCLUSION

All subgroups of patients with DM1 had a substantial number of needs and interventions related to coordinating and navigating within the healthcare system. The subgroup of patients with congenital DM1 had the most needs and interventions compared to the other subgroups.

Impact of restricted access to, and low awareness of, mexiletine on people with myotonia: a real-world European survey

Although mexiletine effectively treats myotonia, supply disruptions affected Europe between 2008-2018. MyoPath was a mixed-methods, cross-sectional, market research survey conducted January-June 2018 to evaluate consequences of limited access to/awareness of mexiletine in people with myotonia. Part A: qualitative structured interviews (clinicians; advocates for adult patients); Part B: quantitative online questionnaire completed by people with self-reported history of myotonia. Part A: Interviews (clinicians, n=12; patient advocates, n=5; 12 countries) indicated poor mexiletine awareness among general neurologists. Patients chose between living with myotonia (other treatments were generally unsatisfactory) or importing mexiletine. Part B: Questionnaire respondents, myotonic dystrophy (DM)1, n=213; DM2, n=128; non-dystrophic myotonia (NDM), n=41; other n=8; (11 countries). Of the respondents, 76/390 (20%) people with awareness of/access to mexiletine described profound improvements in myotonia and health-related quality of life following treatment. Respondents with NDM had greatest mexiletine experience (n=28/41). Mexiletine was associated with fewer falls, less muscle stiffness, increased mobility. Treatment interruptions worsened myotonia and were associated with fatigue, pain, dysphagia, breathing difficulty, impaired digestion, poor sleep. However, 36/54 (67%) of currently treated people expressed anxiety about mexiletine's availability: this finding was expected (MyoPath was undertaken before mexiletine's approval in NDM). MyoPath provides the largest European exploration of patients' views regarding impact of mexiletine on myotonia. Anticipated effects of mexiletine differ between people with different myotonic disorders: myotonia is the main symptom in NDM but one of many potential symptoms affecting those with DM. Nevertheless, findings indicate substantial harm caused to people with myotonia when mexiletine awareness/access is limited.

Prevalence of urinary incontinence and other pelvic floor disorders in women with myotonic dystrophy type 1

Myotonic dystrophy type 1 (DM1) is a neuromuscular disease that can affect the pelvic floor muscles but few studies have investigated pelvic floor disorders, including urinary incontinence. The main purpose of this study was to document the prevalence, characteristics, and impacts of urinary incontinence and other pelvic floor disorders in women with DM1. Associations between pelvic floor disorders and phenotypes, considering age and parity, were explored. Eighty adult women aged 47,1±13,7 years old participated in a cross-sectional study using validated questionnaires, including the International Consultation Incontinence Questionnaire - Urinary Incontinence short form (ICIQ-UI-SF)), the Pelvic Floor Disorder Inventory (PFDI), and the Pelvic Floor Impact Questionnaire short form (PFIQ-SF). The mean score for the ICIQ-UI-SF was 4.3. The mean scores for the subscales of the PFDI were 36.8 for the urinary distress inventory, 74.1 for the colorectal-anal distress inventory, and 43.8 for the pelvic organ prolapse distress inventory. A total of 60% of women reported urinary incontinence and 56.3% anal incontinence. Pelvic prolapse symptoms (>1 symptom) were reported by 25% of women. Findings reveal high prevalence and significant related impacts of these disorders. This provides evidence regarding the importance of screening for these disorders in a clinical setting and the need to explore treatment approaches.

Multiple Case Study of Changes in Participation of Adults with Myotonic Dystrophy Type 1: Importance of Redesigning Accomplishment and Resilience

Background: Myotonic dystrophy type 1 (DM1) is the most prevalent adult form of neuromuscular disorders, for which a decrease of participation with age is known. However, little is known about facilitators and barriers to participation, especially from the perspective of both patients and caregivers. Objective: This study explored and explained changes in participation post-diagnosis with myotonic dystrophy type 1 from the perspective of six adults, their relatives and nurse case managers. Methods: A multiple case study was carried out with these triads (n =  6) using semi-structured individual interviews, medical charts, and a participation patient-reported outcome measure. The six cases were built around three women and three men (age: 40–56 years; disease duration: 19–39 years). Their “relatives” were mainly family members. Nurse case managers had done annual follow-ups with all the adults for approximately ten years. Changes in participation were characterized generally by: 1) heterogeneity, 2) insidious increase in restrictions, and more specifically by: 3) redesigning accomplishment, 4) progressive social isolation, 5) restrictions in life-space mobility, and 6) increasingly sedentary activities. Results: Important facilitators of participation were the adult’s resilience, highly meaningful activities, social support, living arrangement, and willingness to use technical aids. Barriers were mostly related to symptoms and a precarious social network, and were affected by misfit and potential syndemic interactions between personal (e.g., comorbidities) and environmental (e.g., stigma) factors. Conclusion: This study identified key facilitators and barriers and their underlying processes, which should be integrated into the evaluation and intervention framework to optimize participation over time.

Intergenerational Influence of Gender and the DM1 Phenotype of the Transmitting Parent in Korean Myotonic Dystrophy Type 1

Myotonic dystrophy type 1 (DM1) is the most common autosomal-dominant disorder caused by the CTG repeat expansion of the DMPK, and it has been categorized into three phenotypes: mild, classic, and congenital DM1. Here, we reviewed the intergenerational influence of gender and phenotype of the transmitting parent on the occurrence of Korean DM1. A total of 44 parent–child pairs matched for the gender of the transmitting parent and the affected child and 29 parent–child pairs matched for the gender and DM1 phenotype of the transmitting parent were reviewed. The CTG repeat size of the DMPK in the affected child was found to be significantly greater when transmitted by a female parent to a female child (DM1-FF) (median, 1309 repeats; range, 400–2083) than when transmitted by a male parent to a male child (650; 160–1030; p = 0.038 and 0.048 using the Tukey HSD and the Bonferroni test) or by a male parent to a female child (480; 94–1140; p = 0.003). The difference in the CTG repeat size of the DMPK between the transmitting parent and the affected child was also lower when transmitted from a male parent with classic DM1 (−235; −280 to 0) compared to when it was transmitted from a female parent with mild DM1 (866; 612–905; p = 0.015 and 0.019) or from a female parent with classic DM1 (DM1-FC) (605; 10–1393; p = 0.005). This study highlights that gender and the DM1 phenotype of the transmitting parent had an impact on the CTG repeat size of the DMPK in the affected child, with greater increases being inherited from the DM1-FF or DM1-FC situations in Korean DM1.

Remote assessment of myotonic dystrophy type 1: A feasibility study

INTRODUCTION/AIMS

Remote study visits (RSVs) are emerging as important tools for clinical research. We tested the feasibility of using RSVs to evaluate patients with myotonic dystrophy type 1 (DM1), including remote quantitative assessment of muscle function, and we assessed correlations of remote assessments with patient-reported function.

METHODS

Twenty three subjects with DM1 were consented remotely. Toolkits containing a tablet computer, grip dynamometer, and spirometer were shipped to participants. The tablets were loaded with software for video-conferencing and questionnaires about functional impairment, patient experience with technology, and willingness to participate in future remote studies. Grip strength, forced vital capacity, peak cough flow, timed-up-and-go (TUG), and grip myotonia (hand opening time) were determined during RSVs. We assessed correlations of remote assessments with patient-reported outcomes of muscle function and with CTG repeat size.

RESULTS

All 23 subjects completed RSVs. 95% of participants were able to complete all components of the remote study. All toolkit components were returned upon completion. Grip strength and TUG demonstrated moderate to strong correlations with self-reported inventories of upper and lower extremity impairment, respectively (ρ = 0.7 and ρ = -0.52). A total of 91% of subjects expressed interest in participating in future RSVs.

DISCUSSION

Results of this study support the feasibility of using portable devices and video-conferencing for remote collection of patient-reported outcomes and quantitative assessment of muscle function in DM1.

Healthcare resource utilization, total costs, and comorbidities among patients with myotonic dystrophy using U.S. insurance claims data from 2012 to 2019

Background

Myotonic dystrophy (DM) is a rare, inherited disorder with multi-systemic effects that impact the skeletal muscles, eyes, heart, skin and gastrointestinal, endocrine, respiratory, and central nervous systems. DM is divided into two subtypes: DM1 can present from early childhood through adulthood and also has a congenital form (cDM) while DM2 typically manifests during mid-adulthood. Both forms are progressive with no approved treatments, and unmet need for disease-modifying therapies remains high. This study interrogated health insurance claims data to explore the clinical experience, healthcare resource utilization (HCRU), and all-cause costs for DM.

Results

A total of 8541 patients with DM and 242 patients with cDM and their matched controls were selected from a database of over 200 million claimants. HCRU and all-cause costs, including pharmacy, outpatient, and inpatient services, were analyzed across four years in 12-month follow-up periods. Mean all-cause costs per DM patient were high in each of the four periods (range $14,640–$16,704) and showed a steady increase from 13 to 23 months on, while the control group mean costs declined from $9671 in the first 12 months after the index event, to approach the US population average ($5193) over time. For cDM, the highest mean costs were in the first 12-months ($66,496 vs. $2818 for controls), and remained high (above $17,944) across all subsequent periods, while control mean costs approached $0. For DM and cDM, HCRU was higher compared to controls across all study periods and all-cause healthcare costs were mostly driven by inpatient and outpatient encounters. Analysis of all diagnosis codes over the study period (comorbidities) demonstrated an elevated comorbidity profile consistent with the clinical profile of DM.

Conclusions

This study is among the first to utilize claims data to increase understanding of the clinical experience and health economic outcomes associated with DM. The markedly elevated HCRU patterns and comorbidity profile presented here add to the broad body of scientific and clinical knowledge on DM. These insights can inform clinical care and support the development of disease modifying and/or symptom-targeting therapies that address the multi-systemic, progressive nature of DM.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-022-02241-9.

Characteristics of myotonic dystrophy patients in the national registry of Japan

Myotonic dystrophies (DM) are inherited autosomal dominant disorders affecting multiple organs. Currently available therapeutics for DM are limited; therefore, a patient registry is essential for therapeutic development and success of clinical trials targeting the diseases. We have developed a nationwide DM registry in Japan under the Registry of Muscular Dystrophy (Remudy). The registration process was patient-initiated; however, physicians certified the clinical information. The dataset includes all Naarden and TREAT-NMD core datasets and additional items covering major DM clinical features. As of March 2020, we enrolled 976 patients with genetically confirmed DM. The majority (99.9%) of these patients had DM1, with 11.4% having the congenital form. However, 1 patient had DM2. Upon classifying 969 symptomatic DM1 patients based on their age at onset, an earlier onset was associated with a longer CTG repeat length. Myotonia was the most frequent symptom, followed by hand disability, fatigue, and daytime sleepiness. The frequency of hand disabilities, constipation, and visual disturbances was higher for patients with congenital DM. According to a multiple regression analysis of objective clinical measurements related to prognosis and activities of daily living, CTG repeat length strongly influenced the grip strength, forced vital capacity, and QRS time in an electrocardiogram. However, the grip strength was only modestly related to disease duration. This report will shed light on the Japanese national DM registry, which has recruited a significant number of patients. The registry will provide invaluable data for planning clinical trials and improving the standard of care for patients.

Cognitive Deficits, Apathy, and Hypersomnolence Represent the Core Brain Symptoms of Adult-Onset Myotonic Dystrophy Type 1

Myotonic dystrophy type 1 is the most common form of muscular dystrophy in adults, and is primarily characterized by muscle weakness and myotonia, yet some of the most disabling symptoms of the disease are cognitive and behavioral. Here we evaluated several of these non-motor symptoms from a cross-sectional time-point in one of the largest longitudinal studies to date, including full-scale intelligence quotient, depression, anxiety, apathy, sleep, and cerebral white matter fractional anisotropy in a group of 39 adult-onset myotonic dystrophy type 1 participants (27 female) compared to 79 unaffected control participants (46 female). We show that intelligence quotient was significantly associated with depression (P < 0.0001) and anxiety (P = 0.018), but not apathy (P < 0.058) or hypersomnolence (P = 0.266) in the DM1 group. When controlling for intelligence quotient, cerebral white matter fractional anisotropy was significantly associated with apathy (P = 0.042) and hypersomnolence (P = 0.034), but not depression (P = 0.679) or anxiety (P = 0.731) in the myotonic dystrophy type 1 group. Finally, we found that disease duration was significantly associated with apathy (P < 0.0001), hypersomnolence (P < 0.001), IQ (P = 0.038), and cerebral white matter fractional anisotropy (P < 0.001), but not depression (P = 0.271) or anxiety (P = 0.508). Our results support the hypothesis that cognitive deficits, hypersomnolence, and apathy, are due to the underlying neuropathology of myotonic dystrophy type 1, as measured by cerebral white matter fractional anisotropy and disease duration. Whereas elevated symptoms of depression and anxiety in myotonic dystrophy type 1 are secondary to the physical symptoms and the emotional stress of coping with a chronic and debilitating disease. Results from this work contribute to a better understanding of disease neuropathology and represent important therapeutic targets for clinical trials.

Myotonic dystrophy type1: 13years of experience at a tertiary hospital. Clinical and epidemiological study and genotype-phenotype correlation

INTRODUCTION

The incidence of myotonic dystrophy type1 (DM1), a disease with great phenotypic variety, in our region is unknown. This study aims to estimate the incidence of DM1 at our hospital (a reference centre in Aragon, Spain) and to identify the characteristics of our population (genotype-phenotype correlation).

METHODS

Retrospective, descriptive study of 459 patients classified according to the number of CTG repeats, as follows: normal (5-35), premutation (36-50), protomutation (51-80), small expansions (81-150), intermediate expansions (151-1000), and large expansions (>1000). Furthermore, according to clinical phenotype, patients were categorised as unaffected (5-50 CTG repeats), mild form or asymptomatic (51-150), classical form (151-1000), and severe form (>1000).

RESULTS

The incidence of DM1 was 20.61 cases per million person-years (95%CI: 19.59-21.63). An inverse correlation was observed between the number of CTG repeats and the age at genetic diagnosis (ρ=-0.547; 95%CI: -0.610 to -0.375; P<.001). CTG5 was the most frequent polymorphic allele in healthy individuals. Of all patients with DM1, 28.3% presented the mild or asymptomatic form, 59.1% the classical form, and 12.6% the severe form. Inheritance was maternal in 35.1% of cases, paternal in 59.4%, and uncertain in 5.5%. In mild forms, frontal balding in men was the most prevalent phenotypic trait, as well as myotonia and cataracts, while in the classical form, ptosis, facial weakness, voice and pronunciation alterations, myotonia, and fatigue/sleepiness were most frequent.

CONCLUSIONS

The incidence of DM1 in Aragon is significant. Multidisciplinary study of the phenotype of patients with DM1 is key to early diagnosis and personalised management.

Responsiveness of Daytime Sleepiness and Fatigue Scales in Myotonic Dystrophy Type 1

Daytime sleepiness and fatigue are prominent symptoms of myotonic dystrophy type 1 (DM1) that can be amenable to treatment in the context of randomized controlled trials. No study has yet documented whether self-reported measures of daytime sleepiness and fatigue can detect change over time and the meaning of this change. The aim was to explore indicators of responsiveness to change and interpretability for the Daytime Sleepiness Scale and the Fatigue Severity Scale in 115 DM1 prospectively followed patients. Results suggest that these two self-reported questionnaires are sufficiently sensitive to detect changes beyond expected measurement error over time in this population.

Predictors of participation restriction over a 9-year period in adults with myotonic dystrophy type 1

PURPOSE

For slowly progressive neuromuscular disease, prognostic approach and long-term monitoring of participation is a crucial part of rehabilitation services. To improve the prognostic approach, professionals must identify individuals at risk of having higher participation restriction. This study aimed to identify personal and environmental predictors of participation restriction over nine years in adults with myotonic dystrophy type 1 (DM1).

METHODS

A secondary analysis of a longitudinal design comparing baseline with a follow-up nine years later was used with a multidimensional assessment of participation and personal and environmental factors. Based on theoretical models, multiple linear regressions were used.

RESULTS

One hundred and fourteen adults with DM1 were included in the study (63.2% women; 78.9% adult onset; mean (SD) age of 43.5 (10.4) years). When age, sex, phenotype, and education were controlled for, participation restriction was predicted by a longer time to stand and walk, lower grip strength, higher body mass index, absence of perceived impact of myotonia in daily living, use of adapted transportation from community services, and perception of obstacle in physical environment (p < 0.001, adjusted R² = 0.50).

CONCLUSIONS

The majority of predictors of participation restriction can be advantageously modified by rehabilitation and environmental changes, such as politics targeting community services provision or physical environment and services accessibility.Implications for rehabilitationPredictors could better inform rehabilitation professional to recognize individuals at risk of higher participation restriction over time and to target specific interventions based on a prognostic approach.Rehabilitation professionals could inform the people living with myotonic dystrophy type 1 and their relatives of the multifactorial nature of occurrence of participation restriction to diminish the "fatality" associated with a genetic progressive disorder.Predictors allow professionals to assess and intervene in the management of specific factors depending on the rehabilitation goal.Identifying individual with myotonic dystrophy with higher risk of participation restriction could help implement a long-term community based rehabilitation intervention plan targeting both personal and environmental factors.

Utility and Results from a Patient-Reported Online Survey in Myotonic Dystrophies Types 1 and 2

INTRODUCTION

Myotonic dystrophies (DMs) are the most frequent autosomal dominant neuromuscular disorders in adults. Our objective was to evaluate the utility of an online survey in a rare disease as well as to assess and compare the onset and the progression of clinical symptoms in patients with myotonic dystrophy types 1 (DM1) and 2 (DM2).

METHODS

We conducted a patient's reported online survey assessing demographics, disease-related symptoms (age of onset, first symptom, time of diagnosis, current symptoms, inheritance, and family history) combined with capturing current symptoms by validated questionnaires. The questionnaire consisted of open, closed, single- and multiple-choice questions. Multiple answers were possible in some cases. Patients with genetically confirmed DM1 or DM2 who were registered in the German DM registry or the Deutsche Gesellschaft für Muskelkranke e.V. - Diagnostic Group for DMs were invited to participate in this online survey. We calculated descriptive and exploratory analysis, where applicable.

RESULTS

Out of 677 data sets from respondents, 394 were suitable for final analysis, containing completed questionnaires from 207 DM1 (56% female) and 187 DM2 patients (71% female). The median age of onset was 28 years for DM1 and 35 years for DM2. Muscular symptoms were most frequently reported as the first symptom. The onset of myotonia was earlier than the onset of muscle weakness in both DM1 and DM2. Forty-four percent of patients with DM1 and one-third of patients with DM2 indicated muscle weakness as the first symptom. Patients with DM1 were significantly younger when experiencing muscle weakness as first symptom. Fatigue was only mentioned by a small fraction of patients as a first symptom but increased significantly in the course of the disease. There was no statistically significant difference in the incidence of cataracts, cardiac symptoms, and gastrointestinal symptoms between DM1 and DM2. Falls were reported almost equally in both groups, and most of the patients reported 2-3 falls within the past year.

DISCUSSION

Overall, as our results are consistent with the results of clinical studies and online registries, it can be assumed that this type of systematic gathering of data from patients with rare diseases is useful and provides realistic and appropriate results. Due to the nature of online surveys and the absence of an assessor, some uncertainty remains. Furthermore, survey frauds cannot be completely excluded. An additional clinical assessment could confirm the given information and will improve the utility and validity of reported symptoms participants provide in online surveys. Therefore, we recommend a combination of data collecting by online surveys and clinical assessments.

Mixed methods analysis of Health-Related Quality of Life in ambulant individuals affected with RYR1-related myopathies pre-post-N-acetylcysteine therapy

PURPOSE

To characterize Health-Related Quality of Life (HRQoL) in ambulant individuals with RYR1-RM and to determine if a qualitative PRO tool (subjective self-assessment) complements PROMIS and Neuro-QoL scales to detect changes in HRQoL in ambulant individuals with RYR1-RM post N-acetylcysteine (NAC) treatment.

METHODS

The study used a mixed methods research (MMR) design applying methodological triangulation. Qualitative data were collected via semi-structured interviews using open-ended questions. Quantitative data were gathered through PROMIS and Neuro-QoL instruments. Additionally, qualitative data were transformed into quantitative data for subjective self-assessment and frequency analyses.

RESULTS

Qualitative results identified five domains and 33 subdomains as areas of interest. The most valuable were the importance of social impacts, the development of several coping strategies, both physical and psychological, and the identification of fatigue and weakness as key symptoms. Data transformation then categorized more than 3100 citations on frequency analyses, globally and by domain, visit, and participant. Regarding quantitative results, there was no clear evidence that any of the three PRO tools captured positive changes as a result of NAC treatment.

CONCLUSION

Qualitative results showed a comprehensive characterization of HRQoL in this population based on a symptom/patient-centered approach. These findings will inform future studies. Furthermore, given the similar findings across our multiple methods and endpoints, the introduction of MMR may be a valuable, complementary approach to clinical trials. MMR may be especially useful to incorporate in order to address and follow the FDA's guidance and prioritization on the inclusion of affected individuals' perspectives in clinical trials.

Patient Input to Inform the Development of Central Nervous System Outcome Measures in Myotonic Dystrophy

Myotonic dystrophy type 1 (DM1) and myotonic dystrophy type 2 (DM2) are multisystem, genetic disorders caused by repeat expansions on chromosome 19 (DM1) and chromosome 3 (DM2). Although the effects of DM on the skeletal, cardiac, and smooth muscles, as well as the endocrine and central nervous systems, can be disabling, there are no disease-modifying therapies for the disorder. Following a process established by the US Food and Drug Administration (FDA) in 2012 known as the Patient-Focused Drug Development (PFDD) Initiative, Myotonic (formerly the Myotonic Dystrophy Foundation) has been conducting patient- and caregiver-inclusive sessions to explore disease burden as defined by patients and caregivers, and what affected individuals want most from potential new therapies. In September 2017, at Myotonic’s annual conference, a session titled “Bringing the Patient Voice to CNS-Targeting Drug Development in Myotonic Dystrophy” attracted some 350 members of the DM community. During the session, patients and caregivers described CNS disease symptoms, their impact on quality of life, and potential CNS-related targets that they considered important for drug development consideration. These included fatigue and daytime sleepiness; dysregulated sleep; cognitive deficits such as “brain fog,” memory and focus impairment, learning and attention difficulties, and time management challenges; emotional/psychological/behavioral difficulties, including impulsivity, apathy, antisocial behavior, personality changes, and depression; social difficulties, including disconnection, lack of awareness, and feelings of isolation; and general anxieties about the future and potential loss of independence. Improvements in memory and lessening of “brain fog” were considered particularly important.