To determine whether deflazacort at 0.45mg/kg/day is non-inferior to that at 0.9mg/kg/day (recommended regimen) in newly diagnosed boys with Duchenne muscular dystrophy (DMD).

 This randomized, double-blind, non-inferiority trial was conducted between March 2019, and July 2020, at a tertiary-care center in North India. Newly diagnosed ambulatory boys (aged 5-15years) with a baseline 6-minute-walk-distance (6MWD) of ≥150meters were randomized, to receive either 0.45mg/kg/day or 0.9mg/kg/day of deflazacort. The primary endpoint was change in 6MWD from baseline to week-24. The trial was powered for comparison with a non-inferiority margin of -30meters. The study was registered with the Clinical Trial Registry of India (CTRI/2019/02/017388).

Of 97 patients assigned to receive 0.45mg/kg/day(n=49) or 0.9mg/kg/day(n=48), 85 patients (modified intention-to-treat population) completed the trial. Baseline demographic and clinical characteristics were comparable between the groups. The mean change in 6MWD from baseline to week-24 was better for 0.9mg/kg/day group [34.8meters (SD 44)] than 0.45mg/kg/d group [9.7meters (SD 41.5); mean difference -25meters (95%CI -6.5 to -43.5). On subgroup analysis, this difference was significant in boys aged ≥8years (-41.8meters; 95%CI -71.9 to -11.8; P=0.008), and with 6MWD ≤350meters (-35meters, 95%CI -66.4 to -3.5;P=0.03). The incidence of moderate to severe treatment-related adverse events by week-24 was significant for 0.9mg/kg/day group (odds ratio 0.36 [95%CI, 0.14 to 0.89]).