The Dutch Dystrophinopathy Database: A National Registry with Standardized Patient and Clinician Reported Real-World Data1.

Background: Duchenne and Becker muscular dystrophy lack curative treatments. Registers can facilitate therapy development, serving as a platform to study epidemiology, assess clinical trial feasibility, identify eligible candidates, collect real-world data, perform post-market surveillance, and collaborate in (inter)national data-driven initiatives. Objective: In addressing these facets, it's crucial to gather high-quality, interchangeable, and reusable data from a representative population. We introduce the Dutch Dystrophinopathy Database (DDD), a national registry for patients with DMD or BMD, and females with pathogenic DMD variants, outlining its design, governance, and use. Methods: The design of DDD is based on a system-independent information model that ensures interoperable and reusable data adhering to international standards. To maximize enrollment, patients can provide consent online and participation is allowed on different levels with contact details and clinical diagnosis as minimal requirement. Participants can opt-in for yearly online questionnaires on disease milestones and medication and to have clinical data stored from visits to one of the national reference centers. Governance involves a general board, advisory board and database management. Results: On November 1, 2023, 742 participants were enrolled. Self-reported data were provided by 291 Duchenne, 122 Becker and 38 female participants. 96% of the participants visiting reference centers consented to store clinical data. Eligible patients were informed about clinical studies through DDD, and multiple data requests have been approved to use coded clinical data for quality control, epidemiology and natural history studies. Conclusion: The Dutch Dystrophinopathy Database captures long-term patient and high-quality standardized clinician reported healthcare data, supporting trial readiness, post-marketing surveillance, and effective data use using a multicenter design that is scalable to other neuromuscular disorders.

Responsiveness and meaningful thresholds of PROMIS pain interference, fatigue, and physical function forms in adults with idiopathic inflammatory myopathies: Report from the OMERACT Myositis Working Group.

BACKGROUND: A series of qualitative studies conducted by the OMERACT Myositis Working Group identified pain interference, fatigue, and physical function as highly important life impact domains for adults with idiopathic inflammatory myositis (IIM). In this study, our goal was to assess the responsiveness and minimal important difference of PROMIS pain interference (6a), fatigue (7a), and physical function (8b). METHODS: Adults with IIM from USA, Netherlands, Korea, Sweden, and Australia with two "clinical" visits were enrolled in this prospective study. Anchor questions on a Likert scale were collected at baseline, and manual muscle testing (MMT), physician and patient reported global disease activity, and PROMIS instruments were collected at both visits. Responsiveness was assessed with i) ANOVA, ii) paired t-test, effect size and standardized response mean, and iii) Pearson correlation. Minimal important difference (MID), minimal important change (MIC) and minimal detectable change (MDC) values were calculated. RESULTS: 114 patients with IIM (median age 60, 60 % female) completed both visits. Changes in PROMIS instruments were significantly different among anchor categories. Patients who reported improvement had a significant improvement in their PROMIS scores with at least medium effect size, while patients who reported worsening and stability did not show a significant change with weak effect size. PROMIS instruments had weak to moderate correlations with MMT, patient and physician global disease activity. MID was approximately 2-3 points for Pain Interference and 3-4 points for Fatigue and Physical Function forms based on the method used. MIC was approximately 4-5 for improvement of all the instruments, while MDC was 1.7-2 points for Pain Interference and Physical Function and 3.2-3.9 for Fatigue. CONCLUSION: This study provides evidence towards the responsiveness of the PROMIS instruments in a large international prospective cohort of adults with IIM supporting their use as PROMs in adult myositis.

Facilitators and Barriers to Wearing Hand Orthoses by Adults with Duchenne Muscular Dystrophy: A Mixed Methods Study Design.

BACKGROUND: To retard shortening of finger flexors in patients with Duchenne muscular dystrophy (DMD), hand orthoses are prescribed. However, many patients do not wear the orthoses regularly. To optimize orthotic interventions, we need insight into the factors influencing compliance. OBJECTIVE: To evaluate the compliance regarding hand orthoses in an adult DMD population and to explore experiences and perceptions of DMD patients wearing orthoses, and of their caregivers. METHODS: Mixed methods observational study, combining quantitative and qualitative data from medical charts combined with qualitative semi-structured interviews using a constant comparative method and a short validated questionnaire (D-QUEST). RESULTS: 65 medical charts were analyzed. 48 patients were assessed as needing hand orthoses, of whom 37.5 % were compliant. Qualitative data analyses revealed (1) motivation: preservation of hand function; (2) barriers: discomfort and impediments; (3) facilitators: good fit and personalized wearing schedule; (4) fitting process: satisfactory, but patients do not readily seek help when barriers appear. CONCLUSIONS: Patients are motivated to wear hand orthoses, but often discontinue use because of orthosis-and disease-specific barriers. The identification of these barriers leads to practical and feasible recommendations concerning the orthoses and the fitting process, such as less rigid material, preservation of some function while wearing the orthoses, and fixed evaluation points. The findings were confirmed by the D-QUEST.

Early detection of dysphagia and dysarthria in children with neuromuscular disorders: Diagnostic accuracy of a Screeninglist for Physicians.

PURPOSE: Regardless of age or disease stage, children with neuromuscular disorders (NMD) are at risk of developing dysphagia and/or dysarthria. It is important to screen these children regularly in order to detect and treat problems as soon as possible. To date, there are no standardized tools for screening for dysphagia and dysarthria in children with NMD (pNMD). Thus, children are not always referred for assessment by a speech language therapist (SLT). A new screening instrument for dysphagia and dysarthria has been developed, the Screeninglist Physician of the Diagnostic list for Dysphagia and Dysarthria in pediatric NMD (DDD-pNMD). The diagnostic accuracy was estimated in this study. METHODS: Sensitivity and specificity were assessed in 131 children aged 2.0-18.0 years by comparing the outcome of the Screeninglist Physician with the diagnosis of dysphagia and/or dysarthria established by an SLT. RESULTS: The sensitivity of the Screeninglist Physician was 88% and its specificity was 63%. The AUC was 0.83. The prevalence of dysphagia and/or dysarthria was 53%. CONCLUSION: The Screeninglist Physician of the DDD-pNMD is the first valid screening tool for physicians to identify children with NMD with possible dysphagia and/or dysarthria, thereby enabling timely referral to an SLT.

Do we need another trial on exercise in patients with knee osteoarthritis?: No new trials on exercise in knee OA.

OBJECTIVE: We aim to investigate if we need additional trials on exercise in knee osteoarthritis (OA) to accept a certain effect size to be a 'true' effect size, and new studies are not needed anymore. DESIGN: We performed a secondary analyses of a meta-analysis of studies on patients with knee osteoarthritis, on pain immediately post treatment. We performed five different analysis: a) we evaluated publication bias, b) we performed subgroup analysis, c) a sensitivity analysis based on the overall risk of bias (RoB) score, d) a cumulative meta-analysis and e) we developed an extended funnel plot to explore the potential impact of a new study on the summary effect estimate. RESULTS: We included 42 studies with in total 6863 patients. The analyses showed that a) there is no clear publication bias, b) subgrouping did not affect the overall effect estimate, c) the effect estimate of exercise is more consistent (no heterogeneity) in the studies of low RoB, d) the benefit of exercise was clear since 2010 and e) the extended funnel plot suggests that an additional study has a none or very limited impact to change the current effect estimate. CONCLUSION: Exercise is effective and clinically worthwhile in reducing pain immediately post treatment compared to no or minimal interventions in patients with knee OA and adding new data will unlikely change this conclusion.

Respiratory and upper limb function as outcome measures in ambulant and non-ambulant subjects with Duchenne muscular dystrophy: A prospective multicentre study.

The field of translational research in Duchenne muscular dystrophy (DMD) has been transformed in the last decade by a number of therapeutic targets, mostly studied in ambulant patients. A paucity of studies focus on measures that capture the non-ambulant stage of the disease, and the transition between the ambulant and non-ambulant phase. In this prospective natural history study, we report the results of a comprehensive assessment of respiratory, upper limb function and upper limb muscle strength in a group of 89 DMD boys followed in 3 European countries, 81 receiving corticosteroids, spanning a wide age range (5-18 years) and functional abilities, from ambulant (n = 60) to non-ambulant (n = 29). Respiratory decline could be detected in the early ambulatory phase using Peak Expiratory Flow percentage predicted (PEF%), despite glucocorticoid use (mean annual decline: 4.08, 95% CI [-7.44,-0.72], p = 0.02 in ambulant; 4.81, 95% CI [-6.79,-2.82], p < 0.001 in non-ambulant). FVC% captured disease progression in non-ambulant DMD subjects, with an annual loss of 5.47% (95% CI [-6.48,-4.45], p < 0.001). Upper limb function measured with the Performance of Upper Limb (PUL 1.2) showed an annual loss of 4.13 points (95% CI [-4.79,3.47], p < 0.001) in the non-ambulant cohort. Measures of upper limb strength (MyoGrip and MyoPinch) showed a continuous decline independent of the ambulatory status, when reported as percentage predicted (grip force -5.51%, 95% CI [-6.54,-4.48], p < 0.001 in ambulant and a slower decline -2.86%; 95% CI -3.29,-2.43, p < 0.001, in non-ambulant; pinch force: -2.66%, 95% CI [-3.82,-1.51], p < 0.001 in ambulant and -2.23%, 95% CI [-2.92,-1.53], p < 0.001 in non-ambulant). Furthermore, we also explored the novel concept of a composite endpoint by combining respiratory, upper limb function and force domains: we were able to identify clear clinical progression in patients in whom an isolated measurement of only one of these domains failed to appreciate the yearly change. Our study contributes to the field of natural history of DMD, linking the ambulant and non-ambulant phases of the disease, and suggests that composite scores should be explored further.

Don't forget the trunk in Duchenne muscular dystrophy patients: more muscle weakness and compensation than expected.

BACKGROUND: Performing daily activities independently becomes more difficult in time for patients with Duchenne muscular dystrophy (DMD) due to muscle weakness. When performing seated daily activities, the trunk plays an indispensable role besides the upper extremities. However, knowledge is lacking on the interaction between trunk and upper extremities. Therefore the aim was to investigate whether patients with DMD use trunk movement to compensate for reduced arm function when performing seated tasks, and whether this is related to increased muscle activity. METHODS: Eighteen boys with DMD and twenty-five healthy controls (HC) performed several tasks when sitting unsupported, like reaching (and placing) forward and sideward, drinking and displacing a dinner plate. Maximum joint torque and maximum surface electromyography (sEMG) were measured during maximum voluntary isometric contractions. Three-dimensional movements and normalized sEMG when performing tasks were analyzed. RESULTS: Significantly decreased maximum joint torque was found in DMD patients compared to HC. Trunk and shoulder torques were already decreased in early disease stages. However, only maximum trunk rotation and shoulder abduction torque showed a significant association with Brooke scale. In all reaching and daily tasks, the range of motion in lateral bending and/or flexion-extension was significantly larger in DMD patients compared to HC. The trunk movements did not significantly increase with task difficulty (e.g. increasing object weight) or Brooke scale. Normalized muscle activity was significantly higher in DMD patients for all tasks and muscles. CONCLUSIONS: Boys with DMD use increased trunk movements to compensate for reduced arm function, even when performing relatively simple tasks. This was combined with significantly increased normalized muscle activity. Clinicians should take the trunk into account when assessing function and for intervention development, because DMD patients may appear to have a good trunk function, but percentage of muscle capacity used to perform tasks is increased.

Correction to: Trunk, head and pelvis interactions in healthy children when performing seated daily arm tasks.

The authors inadvertently submitted a wrong figure part for publication. Figure 8b should be as follows.

Trunk, head and pelvis interactions in healthy children when performing seated daily arm tasks.

Development of trunk and head supportive devices for children with neuromuscular disorders requires detailed information about pelvis, trunk and head movement in interaction with upper extremity movement, as these are crucial for daily activities when seated in a wheelchair. Twenty-five healthy subjects (6-20 years old) were included to obtain insight in the physiological interactions between these segments and to assess maturation effects. Subjects performed a maximum range of trunk and head movement tasks and several daily tasks, including forward and lateral reaching. Movements of the arms, head, pelvis, and sub-sections of the trunk were recorded with an optical motion capture system. The range of motion of each segment was calculated. Contributions of individual trunk segments to the range of trunk motion varied with movement direction and therefore with the task performed. Movement of pelvis and all trunk segments in the sagittal plane increased significantly with reaching height, distance and object weight when reaching forward and lateral. Trunk movement in reaching decreased with age. Head movement was opposite to trunk movement in the sagittal (> 50% of the subjects) and transverse planes (> 75% of the subjects) and was variable in the frontal plane in most tasks. Both trunk and head movement onsets were earlier compared to arm movement onset. These results provide insight in the role of the upper body in arm tasks in young subjects and can be used for the design of trunk and head supportive devices for children with neuromuscular disorders.

Treatment Outcome, Duration, and Costs: A Comparison of Performance Indicators Using Data from Eight Mental Health Care Providers in The Netherlands.

Assessing performance of mental health services (MHS) providers merely by their outcomes is insufficient. Process factors, such as treatment cost or duration, should also be considered in a meaningful and thorough analysis of quality of care. The present study aims to examine various performance indicators based on treatment outcome and two process factors: duration and cost of treatment. Data of patients with depression or anxiety from eight Dutch MHS providers were used. Treatment outcome was operationalized as case mix corrected pre-to-posttreatment change scores and as reliable change (improved) and clinical significant change (recovered). Duration and cost were corrected for case mix differences as well. Three performance indicators were calculated and compared: outcome as such, duration per outcome, and cost per outcome. The results showed that performance indicators, which also take process variability into account, reveal larger differences between MHS providers than mere outcome. We recommend to use the three performance indicators in a complementary way. Average pre-to-posttreatment change allows for a simple and straightforward ranking of MHS providers. Duration per outcome informs patients on how MHS providers compare in how quickly symptomatic relief is achieved. Cost per outcome informs MHS providers on how they compare regarding the efficiency of their care. The substantial variation among MHS providers in outcome, treatment duration and cost calls for further exploration of its causes, dissemination of best practices, and continuous quality improvement.

[The effect of a short-term group stabilisation training in patients with complex posttraumatic stress disorder]. / Het effect van een kortdurende groepsgewijze stabilisatietraining bij patiënten met een complexe posttraumatische stressstoornis.

BACKGROUND: The international guideline for complex posttraumatic stress disorder (ptsd) from the International Society for Traumatic Stress Studies (istss) recommends treatment in phases, starting with stabilisation treatment. Different forms of stabilisation training have been developed the past few years, one being short-term group stabilisation training.
AIM: To map out the effects of the short-term group training.
METHOD: The research implemented a pre-post design. The training consisted of five group sessions. Questionnaires (bsi, OQ 45 and svl-15) were completed both prior to and after the training. Four domains were assessed: psychosymptomatology in general, depressive symptoms, problems with interpersonal functioning and ptsd-related symptoms. The effect of the training was calculated by paired t-tests.
RESULTS: The questionnaires of the 47 participants who had completed the training were analysed. No significant decrease was observed during the stabilisation training concerning the symptoms of the four evaluated domains.
CONCLUSION: Contrary our expectations, a short-term group-based stabilisation training does not seem to have added value when treating patients with complex ptsd. The results correspond with a recent trend in which the effectiveness of other stabilising methods is questioned. Alternative treatment options are discussed.

[The bidirectional relationship between physical activity and sleep in depressed versus non-depressed individuals]. / De bidirectionele relatie tussen beweging en slaap bij personen met en zonder depressie1.

BACKGROUND: Sleep and physical activity are related, but the direction of this relationship is unclear and it is not known whether the direction differs in depressed and non-depressed persons. AIM: To study the bidirectional relationship between physical activity and sleep in daily life by making repeated measurements in depressed and non-depressed people. METHOD: Every day for 30 consecutive days each depressed (N = 27) and non-depressed (N = 27) participant in our study had to complete an electronic questionnaire relating to subjective sleep quality and sleep duration and were required to wear an accelerometer that recorded physical activity. RESULTS: Multi-level analysis showed that an increase in subjective sleep duration resulted in a decrease in physical activity. The differences between individuals with regard to the direction and strength of this relationship were significant. Changes in physical activity did not predict changes in sleep quality or sleep duration. We did not find any differences in the relationships for depressed and non-depressed participants. CONCLUSION: Change in sleep duration predicts change in physical activity, although there was significant heterogeneity in the results for individuals. Our findings underline the importance of further research and of the development of interventions that are tailored to the precise needs of the individual patient.

The 6-min mastication test: a unique test to assess endurance of continuous chewing, normal values, reliability, reproducibility and usability in patients with mitochondrial disease.

In patients with mitochondrial disease, fatigue and muscle problems are the most common complaints. They also experience these complaints during mastication. To measure endurance of continuous mastication in patients with mitochondrial diseases, the 6-min mastication test (6MMT) was developed. This study included the collection of normal data for the 6MMT in a healthy population (children and adults). During 6 min of continuous mastication on a chew tube chewing cycles per minute, total amount of chewing cycles and the difference between minute 1 (M1 ) and minute 6 (M2 ) were collected in 271 healthy participants (5-80 years old). These results were compared with those of nine paediatric and 25 adult patients with a mitochondrial disease. Visual analogue scale (VAS) scores were collected directly after the test and after 5 min. A qualitative rating was made on masticatory movements. The reproducibility of the 6MMT in the healthy population with an interval of approximately 2 weeks was good. The inter-rater reliability for the observations was excellent. The patient group demonstrated lower total amount of chewing cycles or had greater differences between M1 and M6 . The 6MMT is a reliable and objective test to assess endurance of continuous chewing. It demonstrates the ability of healthy children and adults to chew during 6 min with a highly stable frequency of mastication movements. The test may give an explanation for the masticatory problems in patient groups, who are complaining of pain and fatigue during mastication.

Dystrophic changes in masticatory muscles related chewing problems and malocclusions in Duchenne muscular dystrophy.

Dysphagia in Duchenne muscular dystrophy (DMD) worsens with age, with increasingly effortful mastication. The aims of this study were to describe mastication problems in consecutive stages in a group of patients with DMD and to determine related pathophysiological aspects of masticatory muscle structure, tongue thickness, bite force and dental characteristics. Data from 72 patients with DMD (4.3 to 28.0 years), divided into four clinical stages, were collected in a cross sectional study. Problems with mastication and the need for food adaptations, in combination with increased echogenicity of the masseter muscle, were already found in the early stages of the disease. A high percentage of open bites and cross bites were found, especially in the later stages. Tongue hypertrophy also increased over time. Increased dysfunction, reflected by increasingly abnormal echogenicity, of the masseter muscle and reduced occlusal contacts (anterior and posterior open bites) were mainly responsible for the hampered chewing. In all, this study shows the increasing involvement of various elements of the masticatory system in progressive Duchenne muscular dystrophy. To prevent choking and also nutritional deficiency, early detection of chewing problems by asking about feeding and mastication problems, as well as asking about food adaptations made, is essential and can lead to timely intervention.

[Predicting drop-out during the systems training for emotional predictability and problem solving (STEPPS)]. / Voorspellen van uitval bij vaardigheidstraining emotieregulatiestoornis voor borderlinepersoonlijkheidsstoornis.

BACKGROUND: Drop-out is a complex problem in mental health care and in STEPPS. Research has revealed a variety of predicting factors and has produced contradictory results. AIM: To investigate whether the information available at the start of STEPPS can pinpoint predictors of drop-out. METHOD: The ROM data for 150 patients were used to test the link between the following factors: age, gender, education, employment, substance abuse, anxiety, hostility, interpersonal relations, responsibility and social concordance with drop-out. The method used for testing was logistic regression analysis. RESULTS: Factors that contributed significantly to the prediction of drop-out were gender and employment status. These factors made up 16% of the explained variation (R2 Nagelkerkes) in drop-out. Gender was the strongest predictive factor. Concerning the other factors, no differences were found between groups (drop-out and non-dropouts). CONCLUSION: In its present form STEPPS does not suit a large number of the male participants. Drop-out during STEPPS is hard to predict on the basis of ROM-questionnaires. Future research should focus on preconditions and marginal conditions that influence patients to complete their training.

Reduced mandibular range of motion in Duchenne Muscular Dystrophy: predictive factors.

Patients with Duchenne muscular dystrophy (DMD) experience negative effects upon feeding and oral health. We aimed to determine whether the mandibular range of motion in DMD is impaired and to explore predictive factors for the active maximum mouth opening (aMMO). 23 patients with DMD (mean age 16.7 ± 7.7 years) and 23 controls were assessed using a questionnaire about mandibular function and impairments. All participants underwent a clinical examination of the masticatory system, including measurement of mandibular range of motion and variables related to mandibular movements. In all patients, quantitative ultrasound of the digastric muscle and the geniohyoid muscle and the motor function measure (MFM) scale were performed. The patients were divided into early and late ambulatory stage (AS), early non-ambulatory stage (ENAS) and late non-ambulatory stage (LNAS). All mandibular movements were reduced in the patient group (P < 0.001) compared to the controls. Reduction in the aMMO (<40 mm) was found in 26% of the total patient group. LNAS patients had significantly smaller mandibular movements compared to AS and ENAS (P < 0.05). Multiple linear regression analysis for aMMO revealed a positive correlation with the body height and disease progression, with MFM total score as the strongest independent risk factor (R(2) = 0.71). Mandibular movements in DMD are significantly reduced and become more hampered with loss of motor function, including the sitting position, arm function, and neck and head control. We suggest that measurement of the aMMO becomes a part of routine care of patients with DMD.

Predictive factors for masticatory performance in Duchenne muscular dystrophy.

Patients with Duchenne muscular dystrophy (DMD) report masticatory and swallowing problems. Such problems may cause complications such as choking, and feeling of food sticking in the throat. We investigated whether masticatory performance in DMD is objectively impaired, and explored predictive factors for compromised mastication. Twenty-three patients and 23 controls filled out two questionnaires about mandibular function, and underwent a clinical examination of the masticatory system and measurements of anterior bite force and masticatory performance. In the patients, moreover, quantitative ultrasound of the tongue and motor function measurement was performed. The patients were categorized into ambulatory stage (early or late), early non-ambulatory stage, or late non-ambulatory stage. Masticatory performance, anterior bite force and occlusal contacts were all reduced in the patient group compared to the controls (all p < 0.001). Mastication abnormalities were present early in the disease process prior to a reduction of motor function measurement. The early non-ambulatory and late non-ambulatory stage groups showed less masticatory performance compared to the ambulatory stage group (p < 0.028 and p < 0.010, respectively). Multiple linear regression analysis revealed that stage of the disease was the strongest independent risk factor for the masticatory performance (R(2) = 0.52). Anterior bite force, occlusal contacts and masticatory performance in DMD are severely reduced.

Health-related quality of life and its relation to disease severity in boys with Duchenne muscular dystrophy: satisfied boys, worrying parents--a case-control study.

The progression of Duchenne muscular dystrophy is expected to negatively influence the patients' health-related quality of life, but knowledge of the relationship with disease severity is limited. We investigated the relationship between health-related quality of life (KIDSCREEN-52 questionnaire) and disease severity (clinical assessments of body functions and activities) in 40 boys with Duchenne muscular dystrophy (19 ambulant, 21 wheelchair dependent) who were in different phases of the disease and underwent life-limiting events such as the loss of the ability to ambulate and the ability to lift the arms. In addition, we compared boys' health-related quality of life perceptions with that of their parents. The participants' health-related quality of life was similar to healthy peers' and not influenced by disease severity, except for the physical domain. Parents scored much lower than the boys on the KIDSCREEN-52 domains Self Perception, Moods and Emotions, and Bullying. The latter finding needs attention in the management of Duchenne muscular dystrophy.

Forty-Five Years of Duchenne Muscular Dystrophy in The Netherlands.

BACKGROUND: Duchenne muscular dystrophy (DMD) is a progressive muscle disease. No curative therapy is currently available, but in recent decades standards of care have improved. These improvements include the use of corticosteroids and mechanical ventilation. OBJECTIVE: To present a detailed population based report of the DMD disease course in The Netherlands (1980-2006) and evaluate the effect of changes in care by comparing it with an historical Dutch DMD cohort (1961-1974). METHODS: Information about DMD patients was gathered through the Dutch Dystrophinopathy Database using a standardized questionnaire and information from treating physicians. RESULTS: The study population involved 336 DMD patients (70% of the estimated prevalence), of whom 285 were still alive. Mean age at disease milestones was: diagnosis 4.3 years, wheelchair dependence 9.7 years, scoliosis surgery 14 years, cardiomyopathy (fractional shortening <27%) 15 years, mechanical ventilation 17 years and death 19 years. Within our cohort, corticosteroid use was associated with an increased age of wheelchair dependence from 9.8 to 11.6 years (p < 0.001). When comparing the recent cohort to the historical cohort, mean survival improved from 17 to 27 years (p < 0.001). CONCLUSION: The current study gives detailed information about the disease course of DMD patients, provides evidence for the positive effect of steroid treatment and mechanical ventilation and supports the use of patient registries as a valuable resource for evaluating improvements in care.

Reliability of the walking energy cost test and the six-minute walk test in boys with Duchenne muscular dystrophy.

The walking energy cost test (WECT) is a useful tool when measuring ambulatory function in children with motor disorders. However, data on the reliability of this test in Duchenne muscular dystrophy (DMD) is not available. In this study we established the reliability of the WECT and the commonly used six-minute walk test (6MWT) in 19 boys with DMD, aged 6-12years. Participants performed the WECT and 6MWT twice within three weeks. Reliability was determined for walking distance (D, m) and gross energy cost (EC, Jkg(-1)m(-1)), using the intraclass correlation coefficient (ICC2,1) and smallest detectable change (SDC). Reliability for walking distance was good, with an ICC of 0.92 [95% CI: 0.81-0.97] and 0.83 [CI: 0.53-0.94] for the 6MWT and WECT, respectively, and an ICC of 0.85 [CI: 0.64-0.94] for gross EC. SDCs were 12.2% for D6MWT, 12.7% for DWECT and 18.5% for gross EC. In conclusion, in young boys with DMD, the reliability of both the WECT and 6MWT for assessing walking distance is adequate. Gross EC, as assessed with the WECT is also reliable and sufficiently sensitive to detect change in walking strain following interventions at group level.