Objective: To describe trends in corticosteroid treatment during 2000-2015 among individuals with Duchenne muscular dystrophy (DMD) ascertained by the population-based Muscular Dystrophy Surveillance, Tracking and Research Network (MD STARnet).
Methods: MD STARnet ascertained individuals with DMD in six US surveillance areas (Colorado, Iowa, Piedmont Region of North Carolina, South Carolina, Utah/Nevada, and 21 western counties in New York). We included 373 males with DMD born and followed during 2000-2015. Age at first offering and use of corticosteroids were collected from medical records. Median ages and 95% confidence intervals [CIs] at first offering/use are reported from Kaplan-Meier (K-M) curve estimation. Cox proportional hazards modeling estimated hazards (95%CI) of use separately by birth cohort (2000-2004/2005-2009/2010-2015), race/ethnicity (non-Hispanic Whites [NH-W]/non-Hispanic Blacks [NH-B]/Hispanics/Other) and known family history of DMD (Yes/No), along with MD STARnet site as a random effect.
Results: Most individuals were born before 2010 (89.3%), were NH-W (68.1%), and had no known family history of DMD (73.2%). Overall, 75.6% were offered and 68.9% used corticosteroids. Deflazacort was used by 31.5%, mostly by NH-W (86.4%). K-M median ages for 332 males with known periods of steroid use were 6.8 (95%CI=6.3,7.2) at first offering and 7.2 (95%CI=6.8,7.6) at first use. During any given year of follow-up, we observed a statistically significantly lower hazard of being offered (HR=0.48, 95%CI=0.27,0.86), but not of using corticosteroids (HR=0.57, 95%CI=0.32,1.02) for NH-B compared to NH-W. A known family history of DMD was not significantly associated with offering (HR=0.76, 95%CI=0.55,1.04) corticosteroids, but showed a lower hazard of use (HR=0.61, 95%CI=0.43, 0.88).
Discussion: Individuals with a prior family history may be less likely to initiate corticosteroids. We did not observe any perceivable barriers to initiation of corticosteroids among NH-B. As deflazacort usage was mostly found in NHW, the possibility of barriers to its usage among racial/ethnic minorities should be explored.