Onset of Key Clinical Milestones in Children With Duchenne Muscular Dystrophy

The real-world data on the prevalence of key clinical milestones across varying ages among patients with DMD are consistent with published findings.

Real-world data revealed heterogeneity of estimates for the prevalence of key clinical milestones among patients of varying ages with Duchenne muscular dystrophy (DMD), according to study findings published in the Journal of Neuromuscular Diseases.

Researchers in the United States conducted a real-world, retrospective, cohort study to characterize key clinical milestones during the course of disease progression among patients with DMD. They obtained information from IBM MarketScan commercial insurance databases between April 1, 2013 to March 31, 2018, identifying 1964 eligible patients with DMD.

The researchers used real-world data to estimate the ages when key clinical milestones occurred with greatest prevalence during the course of the disease. These key clinical milestones of interest included neurologic and/or neuropsychiatric involvement, loss of ambulation, scoliosis, cardiomyopathy, and respiratory involvement.

Pulmonary and cardiac comorbidities were among the most frequent followed by respiratory infectious diseases, anxiety, and asthma.

… [T]he findings of this study also help delineate the types of outcomes that one can well characterize using existing claims data for cohort studies, and considerations on the methodology to do so.

Neurologic/neuropsychiatric  and respiratory involvement occurred in 27% and 34% of the cohort, respectively. Around 41-43% of children between the ages of 8 and 13 presented with neurological/neuropsychiatric involvement, while 45% of patients aged 14 to 19 years presented with respiratory involvement.

Approximately 45% of the patients experienced loss of ambulation. Over half of them (55%) were between the ages of 11 and 13 years old.

Scoliosis occurred in 30% of patients with DMD, progressing as age increased. Approximately 38% of those with scoliosis were between ages 8 to 10 years old and 52% were between ages 11 to 13 years old.

Cardiomyopathy occurred in 46% of the cohort. Around 68% of patients aged 14 to 16 years presented with cardiomyopathy, while 58% of patients aged 17 to 19 years presented with cardiomyopathy.

“Variability in estimates [of key clinical milestones] reflect the clinical heterogeneity experienced by those with DMD but also the impact of observation windows on the ability to ascertain key clinical outcomes in DMD,” the authors stated.

The researchers added that “… [T]he findings of this study also help delineate the types of outcomes that one can well characterize using existing claims data for cohort studies, and considerations on the methodology to do so.”

The real-world data can help clinicians characterize the clinical outcomes in DMD.

Study limitations included potential misclassification on exposure for due to lack of standardized case definitions, the relatively short follow-up period (median 1.7 years), the age-restricted sensitivity analysis, the exclusion of patients outside of commercial insurance plans, and the development of more sensitive diagnostic tools and research that identifies complications at earlier ages in the disease progression.

Disclosures: The study was funded by Sarepta Therapeutics, Inc. Two authors were employed by Sarepta. Several others received funding from Sarepta. One author disclosed multiple affiliations with biotech and/or pharmaceutical companies.


Szabo SM, Klimchak AC, Qian C, Iannaccone S, Popoff E, Gooch KL. Characterizing the occurrence of key clinical milestones in Duchenne muscular dystrophy in the United States using real-world data. J Neuromuscul Dis. Published online October 8, 2022. doi:10.3233/JND-220816