A retrospective study recently published in Muscle & Nerve followed Canadian patients with Duchenne muscular dystrophy (DMD) long-term to uncover treatment patterns and disease outcomes.
Few studies have evaluated patient outcomes in DMD using health insurance administrative data, which not only allows researchers to sample a large number of individuals but also provides a fairly accurate representation of the typical clinical care received by patients.
The authors utilized Canadian administrative datasets, which include the entire population of each province and often provide long-term follow-up. They included 198 patients in Manitoba who were diagnosed with muscular dystrophy between Jan. 1, 1998 and March 31, 2020. All individuals were 10 years of age or younger at the time of diagnosis.
Patients were followed for an average of 11 years. The study found that during this time, 25.8% of participants used corticosteroids, with prednisone being prescribed most often. The average duration of corticosteroid use was 407.8 days. Among patients born in or after 2005, this value increased to 527.9 days.
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The most commonly recorded clinical outcome was cardiovascular complications (32.3%), with a median age of diagnosis of 12.5 years. The second most common outcome was severe respiratory complications (20.2%), with a median age of 14 years. Scoliosis was observed in 17.7% of the study cohort, with a median age of diagnosis of 12 years.
The study also found an overall mortality rate of 13.6% with a median age of 19 years. The probability of survival by 25 years of age was estimated to be 85%.
The authors caution that there are limitations to using this type of data, including variability in billing codes and inability to definitively classify events as being related to DMD. Additionally, there is no DMD-specific billing code, meaning the authors had to devise an algorithm to determine probable cases among those with a muscular dystrophy diagnosis.
“Despite limitations associated with the use of administrative data to understand clinical outcomes to specifically track individual patient progression, these analyses provide valuable insight in terms of the occurrence of key clinical events among the population with DMD and contribute to the evidence regarding the natural history of DMD,” the study concluded.
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