Paediatric traumatic brain injury severity and acute care costs.

### What is already known? ### What this study adds? Traumatic brain injury (TBI) in children is the leading cause of disability and is associated with a significant burden of disease globally.1 Population-based studies reporting the incidence of TBI in Australia have focused on hospitalised patients.2 Most paediatric head trauma results in mild TBIs that do not require hospitalisation.1 In Australia, a 13% increase in emergency department (ED) presentations for paediatric head injuries were reported between 2014 and 2018.3 The most common mechanisms of head injuries are falls for children less than 11 years and transportation-related injuries for children 11 to 16 years.2 While falls are the most common mechanism of head injury in children and can be associated with the most long-term costs, transportation-related TBIs incur high acute care costs, with pedestrian injuries having the highest mean per-patient cost.2 3 This research estimates the effect of mechanisms of injury and severity on the acute care costs of TBI in children. A planned subanalysis of children <18 years enrolled in the prospective multicentre Australasian Paediatric Head Injury Study (APHIRST) between 2011 and 2014. The study was designed to validate clinical decision rules for the diagnosis of TBI in children.4 The eight participating sites were all government-funded large tertiary hospitals. The standard definition of acute care was used, including emergency presentations with discharge and acute admissions until hospital discharge. Common mechanisms of head injuries were identified a priori and were recorded at the time of patient enrolment …