Early developmental milestones in Duchenne muscular dystrophy

Aim To investigate the differences in attainment of developmental milestones between young males with Duchenne muscular dystrophy (DMD) and young males from the general population. Method As part of the case-control 4D-DMD study (Detection by Developmental Delay in Dutch boys with Duchenne Muscular Dystrophy), data on developmental milestones for 76 young males with DMD and 12 414 young males from a control group were extracted from the health care records of youth health care services. The characteristics of DMD were acquired from questionnaires completed by parents. Logistic regression analyses were performed with milestone attainment (yes/no) as the dependent variable and DMD (yes/no) as the independent variable, with and without adjustment for age at visit. Results The mean number of available milestones was 43 (standard deviation [SD]=13, range: 1-59) in the DMD group and 40 (SD=15, range: 1-60) in the control group. The presence of developmental delay was evident at 2 to 3 months of age, with a higher proportion of young males with DMD failing to attain milestones of gross/fine motor activity, adaptive behaviour, personal/social behaviour, and communication (range age-adjusted odds ratios [ORs]=2.3-4.0,p<0.01). Between 12 and 36 months of age, differences in the attainment of developmental milestones concerning gross motor activity increased with age (range age-adjusted ORs=10.3-532,p<0.001). We also found differences in developmental milestones concerning fine motor activity, adaptive behaviour, personal/social behaviour, and communication between 12 and 48 months of age (range age-adjusted ORs=2.5-9.7,p<0.01). Interpretation We found delays in the attainment of motor and non-motor milestones in young males with DMD compared to the control group. Such delays were already evident a few months after birth. Developmental milestones that show a delay in attainment have the potential to aid the earlier diagnosis of DMD.