Background: Natural history data are essential for trial design in Duchenne (DMD) and Becker muscular dystrophy (BMD), but recruitment for observational studies can be challenging. Objective: We reviewed reasons why patients or caregivers declined participation, and compared characteristics of participants and non-participants to assess possible selection bias in four observational studies, three on DMD and one on BMD. Methods: Three pediatric DMD studies focused on cross-sectional cognitive function and brain MRI (DMDbrain, n = 35 and DMDperfusion, n = 12), and on longitudinal upper extremity function and muscle MRI (DMDarm, n = 22). One adult BMD study assessed longitudinal functioning (n = 36). Considerations for non-participation were retrospectively reviewed from screening logs. Age, travel-time, DMD gene mutations and age at loss of ambulation (DMDarm and BMD study only), of participants and non-participants were derived from the Dutch Dystrophinopathy Database and compared using nonparametric tests (p < 0.05). Results: The perceived burden of the protocol (38.2%), use of MRI (30.4%), and travel-time to the study site (19.1%) were the most frequently reported considerations for non-participation. Only few patients reported lack of personal gain (0.0– 5.9%). Overall, participating patients were representative for the studied sub-populations, except for a younger age of DMDarm study participants and a complete lack of participants with a mutation beyond exon 63. Conclusion: Optimizing patient involvement in protocol design, improving MRI experiences, and integrating research into clinics are important factors to decrease burden and facilitate participation. Nationwide registries are essential to compare participants and non-participants and ensure representative observational research. Specific effort is needed to include patients with distal mutations in cognitive studies.
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.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).Information about DMD patients was gathered through the Dutch Dystrophinopathy Database using a standardized questionnaire and information from treating physicians.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).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.
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