Efficacy of corticosteroid in decreasing scoliosis and extending time to loss of ambulation in a single clinic: an effectiveness trial

Relationship between growth and ambulation loss in Duchenne muscular dystrophy boys on steroids

BACKGROUND AND PURPOSE

Treatment with glucocorticoids (GCs) is part of the standard of care in Duchenne muscular dystrophy, but excess weight gain and height stunting are common side-effects. It is still unclear how these growth-related side-effects affect motor function.

METHODS

This retrospective cohort study utilized 2228 observations from 648 participants in the UK NorthStar database who had growth and ambulation data recorded between 2006 and 2020. Joint modelling was used to analyse the effect of longitudinal growth centiles on loss of ambulation with respect to GC type and regimen.

RESULTS

Loss of ambulation was observed in 113 patients. National estimates of loss of ambulation age were updated by GC group and showed no significant association between loss of ambulation risk and absolute growth centile. However, yearly drift in weight and/or height centile had an associated risk effect on loss of ambulation. Over a 2-year period, a yearly drift in weight from the 50th to the 75th, 75th to the 90th and 90th to the 95th centile was associated with 138%, 118% and 64% increased risk of loss of ambulation, respectively. Conversely, a 2-year drift in height from the 50th to the 25th, 25th to the 10th and 10th to the 5th centile was associated with 53%, 49% and 35% decreased risk of loss of ambulation, respectively.

CONCLUSIONS

Our results suggest a complex relationship between growth and loss of ambulation in Duchenne muscular dystrophy boys on chronic GCs, the first step in understanding the effects of drugs which also affect growth patterns.

Current Concepts in the Orthopaedic Management of Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD), a genetic condition marked by progressive muscle degeneration, presents notable orthopaedic challenges, especially scoliosis, which deteriorates patients' quality of life by affecting sitting balance and complicating cardiac and respiratory functions. Current orthopaedic management strategies emphasize early intervention with corticosteroids to delay disease progression and the use of surgical spinal fusion to address severe scoliosis, aiming to enhance sitting balance, alleviate discomfort, and potentially extend patient lifespan. Despite advancements, optimal management requires ongoing research to refine therapeutic approaches, ensuring improved outcomes for patients with DMD. This review synthesizes recent findings on surgical and nonsurgical interventions, underscoring the importance of a multidisciplinary approach tailored to the dynamic needs of patients with DMD.

A Mixed-Method Study Exploring Patient-Experienced and Caregiver-Reported Benefits and Side Effects of Corticosteroid Use in Duchenne Muscular Dystrophy

BACKGROUND

Corticosteroids are recommended to all people with Duchenne as standard of care; experience data is important to guide corticosteroid decision making and as a comparator for new treatment options.

OBJECTIVE

This study assesses patient and caregiver-reported benefits and side effects from corticosteroids to treat Duchenne muscular dystrophy, their importance, and satisfaction.

METHODS

Using one-on-one interviews (n = 28) and an online survey (n = 236), parents and adults with Duchenne reported corticosteroid benefits and side effects rated as both experienced and important.

RESULTS

Benefits to breathing, heart function, arm strength, slowing progression of weakness, and getting around were rated as particularly important, regardless of ambulatory status. Important side effects included increased fracture risk, unwanted weight gain, and diabetes/prediabetes. Parents rated behavior issues and adults rated delayed puberty as having high importance. Being ambulatory was independently associated with reporting more net benefit (p = 0.02). For side effects, parent scores were significantly higher than adult score (p = 0.02). Corticosteroid type was not significant. Participants were, overall, satisfied with corticosteroids (means ranging from 6.2 to 7.7 on a scale of 0-10), with no significant differences based on corticosteroid type.

CONCLUSIONS

Overall, most participants were satisfied with the use of corticosteroids. While a range of side effects were rated as important and relatively common, individuals using corticosteroids and their caregivers indicate that benefits outweigh the side effects. Qualitative data indicate that high acceptability is influenced by lack of treatment alternatives. Patient experience data on use of corticosteroids in Duchenne may be relevant to drug development, regulatory assessment of new treatments, and to families making decisions about corticosteroid use.

No difference in postoperative complication rates or cardiopulmonary function for early versus late scoliosis correction in Duchenne muscular dystrophy

BACKGROUND

Given reduced rates of both pulmonary function decline and scoliosis progression with steroid treatment in Duchenne muscular dystrophy (DMD), the role of early scoliosis surgery has been questioned. The purpose of this study was to compare the postoperative complication rates of early versus late scoliosis correction in DMD.

METHODS

This study was a retrospective cohort, conducted at an academic tertiary level children's hospital. Patients with DMD who underwent posterior scoliosis correction, with preoperative pulmonary function testing [forced vital capacity (FVC)] were included and divided into two groups by preoperative curve angles: ≤ 45° and > 45°. The primary outcome variable was postoperative complications by Clavien-Dindo classification grading. Secondary outcome variables included postoperative complications occurring after the first 90 days, age at surgery, duration of wheelchair dependency preoperatively, pulmonary function, steroid utilization, shortening fraction by echocardiogram, surgery duration, intensive care unit/hospital length of stay, days intubated, infection, and percent curve correction. Two-tailed t-test and Chi-square testing were used for analysis of patient factors and Clavien-Dindo complication grade, respectively.

RESULTS

Thirty-one patients were included with a total follow-up of 8.3 ± 3.2 years, 4.8 ± 2.2 years post-spinal fusion. Steroid treatment (prednisone, deflazacort) was utilized for 21 (67.7%) patients. Primary curve correction was not different between groups (65.0% vs 71.4% [p = 0.37]). There were no significant differences in Clavien-Dindo classification grades between groups (p > 0.05). For the entire cohort, the overall complication rate was higher for patients with steroid treatment (61.9% vs 10.0% [p = 0.008]). Neither forced vital capacity nor fractional shortening on echocardiogram was different between groups at final follow-up (p = 0.6 and p = 0.4, respectively).

CONCLUSION

The comparable risk of perioperative complications for early and late scoliosis correction supports a "watchful waiting" approach, whereby curves less than 45° can be carefully followed while cardiopulmonary function is maintained. Patients undergoing steroid treatment should be counseled regarding the higher risk of postoperative blood transfusion and deep wound infection.

LEVEL OF EVIDENCE

III Retrospective cohort.

The Relationship between Obesity and Clinical Outcomes in Young People with Duchenne Muscular Dystrophy

Background: Duchenne muscular dystrophy (DMD) is a severe X-linked neuromuscular disorder. Young people with DMD have high rates of obesity. There is emerging evidence that a higher BMI may negatively affect clinical outcomes in DMD. This study aimed to explore the relationship between obesity and clinical outcomes in DMD. Methods: This was a retrospective clinical audit of young people (two–21 years) with DMD. Height and weight were collected to calculate BMI z-scores to classify obesity, overweight and no overweight or obesity (reference category). Cox proportional hazards models determined the impact of obesity at five to nine years on clinical milestones including time to: loss of ambulation, timed function test cut-offs, obstructive sleep apnoea (OSA) diagnosis and first fracture. Results: 158 young people with DMD were included; most (89.9%) were steroid-treated. Mean follow-up was 8.7 ± 4.7 years. Obesity prevalence increased from age five (16.7%) to 11 years (50.6%). Boys with obesity at nine years sustained a fracture earlier (hazard ratio, HR: 2.050; 95% CI: 1.038–4.046). Boys with obesity at six to nine years were diagnosed with OSA earlier (e.g., obesity nine years HR: 2.883; 95% CI: 1.481–5.612). Obesity at eight years was associated with a 10 m walk/run in 7–10 s occurring at an older age (HR: 0.428; 95% CI: 0.207–0.887), but did not impact other physical function milestones. Conclusions: Although 50% of boys with DMD developed early obesity, the impact of obesity on physical function remains unclear. Obesity puts boys with DMD at risk of OSA and fractures at a younger age. Early weight management interventions are therefore important.

Deflazacort dose optimization and safety evaluation in Duchenne muscular dystrophy (DOSE): A randomized, double-blind non-inferiority trial

BACKGROUND

US food and drug administration has recently approved deflazacort for Duchenne muscular dystrophy (DMD) and recommended the dosage of 0.9 mg/kg/d for patients aged ≥5years. However, data assessing the minimal efficacious dose and need of dose-titration based on age or disease severity is limited.

OBJECTIVE

To determine whether deflazacort 0.45 mg/kg/d (proposed lower dosage) is non-inferior to 0.9 mg/kg/d among newly diagnosed patients with DMD.

METHOD

A double-blinded, non-inferiority, randomized trial, conducted between December 2018 and July 2020. Newly diagnosed patient aged 5-15 years with genetic or muscle biopsy confirmed DMD and baseline 6-min walk distance (6MWD) > 150 m were screened. Patients were randomly assigned (1:1), stratified to prespecified subgroups by age (≤7years and >7years), and baseline 6MWD (≤350 m and >350 m), to receive either 0.45 mg/kg/d or 0.9 mg/kg/d regimens. The primary endpoint was the change in 6MWD, from baseline to week-24 of intervention. The trial was powered with a predefined, non-inferiority margin of 30 m. The analyses were by modified intention-to-treat (mITT).

RESULT

A total of 97 patients were enrolled, 40 receiving 0.45 mg/kg/d and 45 receiving 0.9 mg/kg/d deflazacort comprised of mITT population. For primary endpoint analysis the mean (SD) change in 6MWD from baseline to week-24 was 9.7 m (41.5) in deflazacort 0.45 mg/kg/d, and 34.7 m (43.5) for 0.9 mg/kg/d. The mean difference in change in 6MWD across the group was 24.8 m (95% CI 6.7 to 43, p value 0.008). The mean difference in change in 6MWD in the subgroups of boys ≤7 years of age was 21.8 m (95% CI -0.82, 44.5, p = 0.059), with baseline 6MWD of >350 m was 19.9 m (95% CI -2.4, 42.4; p = 0.08). The incidence of combined moderate to severe treatment-related adverse events was significant in the 0.9 mg/kg/d group by week 24 (odds ratio 0.36 [95% CI, 0.14 to 0.89], p = 0.03).

DISCUSSION

The efficacy of proposed low dose deflazacort in comparison to the standard dose did not meet the prespecified criteria for non-inferiority. The low dose deflazacort was non-inferior in subgroup of patients with age ≤7 years and baseline 6MWD of >350 m.

TRIAL REGISTRATION

Clinical Trial Registry-India Identifier: CTRI/2019/02/017388.

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

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