Healthcare transition refers to the planned movement of adolescents and young adults with chronic conditions from child-centred to adult-oriented healthcare. Medical advances have increased life-expectancy for many children with chronic and complex conditions, creating a growing need for effective transition into adult healthcare. Transition models exist for some child-onset conditions like diabetes and cancer, but little is known about effective transition for individuals with severe neurological impairment (SNI). SNI encompasses a group of child-onset, life limiting conditions characterised by motor and cognitive impairment, significant medical complexity, and high care needs. While paediatric neuro disability services provide holistic, coordinated care for children with SNI, there is no equivalent adult subspecialty. There is limited expertise among adult providers in managing rare conditions previously seen mainly in paediatrics. Adult SNI care is often fragmented and reactive, with no single medical team providing clinical oversight. These challenges can negatively affect patient health and increase health system burden. Improving SNI healthcare transition in Ireland is a national policy priority. To support the development of effective transition pathways, more information is needed on the characteristics and healthcare utilisation patterns of this population during adolescence and young adulthood. This project addresses these knowledge gaps, estimating prevalence of SNI amongst young people in Ireland and analysing their use of prescription medications and hospitals during adolescence and young adulthood. Secondary datasets include: Health Service Executive-Primary Care Reimbursement Service pharmacy claims, mortality data, Hospital In-patient Enquiry. Quantitative analytic techniques will be used to estimate prevalence, examine polypharmacy, potentially inappropriate prescribing, co-morbidities, prescription expenditure, associations between age and prescribing patterns, hospital length of stay, and within hospital re-admissions. The project team, comprising relatives of young people with SNI, policymakers, paediatric and adult healthcare providers, and researchers is well-placed to translate the findings into key recommendations to support SNI healthcare transition policy, planning and delivery.