Reference curves of motor function outcomes in young steroid-na?ve males with Duchenne muscular dystrophy

AimTo investigate functional motor performance in a large cohort of young steroid-naive males with Duchenne muscular dystrophy (DMD) and typically developing males, and to develop specific reference curves for both groups. Also, to describe associations between anthropometric values and functional motor outcomes.MethodCross-sectional data of 196 steroid-naive males with DMD aged 4 to 8 years and 497 typically developing males aged 2 years 6 months to 8 years were included. Both groups were evaluated with the time to rise from the floor test, 10-metre walk/run test, 6-minute walk test, and North Star Ambulatory Assessment. Reference curves with centiles 5%, 10%, 25%, 50%, 75%, 90%, and 95% were estimated using quantile regression.ResultsMales with DMD scored significantly worse on all functional motor outcomes than age-matched typically developing males (p < 0.001): 89% to 95% of the males with DMD scored below the 5th centile of the typically developing males. No or weak correlations exist between anthropometric values and functional motor outcomes.InterpretationThe estimated reference curves can support consultation with families of young males with DMD and can support the evaluation of treatment for reaching motor skills and functional motor outcomes compared with typically developing males.