Epidemiology of Developmental and Epileptic Encephalopathy and of Intellectual Disability and Epilepsy in Children.

Epilepsy and developmental impairment prior to age 16 years occurs in 1 in 340 children, with 1 in 590 having a DEE and 1 in 800 ID+E. These individuals require significant health and community resources, therefore these data will inform complex health service and education planning. Epidemiological studies have focused on early childhood onset DEEs. These do not fully reflect the burden of these disorders as 27% of DEEs and 70% of ID+E begin later, with seizure onset after 3 years. Understanding the cumulative incidence of specific syndromes together with the broad group of DEEs is essential for planning of therapeutic trials. Given trials focus on specific syndromes there is a risk that effective therapies will not be developed for 1/3 of children with DEE.