Developmental delay in Duchenne Muscular Dystrophy: A case-control study of a Dutch population: abstract

Background and aims: Diagnostic delay often occurs in the treatment of Duchenne Muscular Dystrophy (DMD). As the early course of the disease is defined by developmental delay, detecting this delay may aid timely diagnosis. Our aim is to investigate the differences in attainment of developmental milestones, medical referrals and symptoms between boys with DMD and boys from the general population. Methods: Within the 4D-DMD study (Detection by Developmental Delay in Dutch boys with Duchenne Muscular Dystrophy), data on the attainment of milestones, medical referrals, and symptoms in boys with and without DMD were extracted from the (electronic) health records of the Youth Health Care Service. Additional information for boys with DMD was acquired from questionnaires. Results: In total, health records from 76 boys with DMD and from 19,086 boys from the general population without DMD, and questionnaires from 71 parents of boys with DMD were retrieved. The presence of developmental delay became evident shortly after birth, at 2-3 months of age with a lower proportion of DMD boys attaining milestones of fine and gross motor activity (Odds Ratios (OR) ranged between 3.3 and 3.6, p<0.001). Between 12 and 24 months of age, differences in attainment of milestones concerning the gross motor became greater between the DMD group versus the control group activity (OR ranges: 10.6-82.4, p<0.001). Also, smaller, but significant differences were found in the milestones concerning fine motor activity, adaptive and personal/social behavior and communication between 12 and 48 months of age (OR ranges: 3.1-6.0, p<0.001). Before the diagnosis of DMD, boys with DMD were referred more often to physical therapy, speech-language therapy, an ENT-specialist and preschool educational intervention compared to the control group. Symptoms that appeared more often in DMD boys compared to peers were falling more frequently, stiff way of walking, a younger appearance than his chronological age and pseudohypertrophy. Conclusions: Our study found substantial differences in milestone attainment, medical referrals and symptoms in boys with DMD compared to controls, which were observable from a young age. Main question: How can we use this information within youth health care for the early detection of boys with DMD?