BACKGROUND: The progression of DMD is characterized by loss of ambulation and upper limb function, cardiorespiratory impairment, and early mortality.
OBJECTIVES: This study aimed to characterize real-world corticosteroid use among a closed Canadian DMD population from the period spanning the introduction of corticosteroids for the management for DMD.
METHODS: Linked longitudinal population-based single-payer physician, hospitalization, and pharmacy records from the Manitoba Population Research Data Repository were used to identify all males with a first diagnosis of muscular dystrophy at ?10 years of age with corticosteroid use during 1998-2020. Patient demographics, the frequency of corticosteroid use, the proportion of days covered (PDC), and total duration of coverage were summarized. Results were stratified according to birth year to explore differences in corticosteroid treatment in relation to guideline changes. An incident cohort was used to identify age at first corticosteroid use.
RESULTS: Of 51 male patients with DMD treated with corticosteroids (mean [SD] age at index, 6.3 [5.8] years), most (73%) received prednisone; 22% used deflazacort and the remaining used both. Over the period, the mean (SD) PDC was 0.3 (0.4), corresponding to a total mean (SD) duration of coverage per patient of 13.4 (19.6) months. The mean (SD) PDC increased from 0.2 (0.2) for patients born before 2005 (n=33) to 0.6 (0.5) for patients born after 2005 (n=18) (and duration, 11.2 (21.1) to 17.3 (16.3) months), reflecting more regular use among patients in the post- than pre-corticosteroid era. The 16 incident patients from the pre-corticosteroid era were first dispensed corticosteroids around age 10 years, vs. 5-6 years of age among the 15 incident patients from the post-corticosteroid era.
CONCLUSIONS: While some patients may have accessed deflazacort through a special access program and would not have been captured, these data highlight contemporary real-world treatment patterns among patients with DMD before and after the emergence of corticosteroids.