Epidemiology of road traffic accident-related head injuries: a multicenter retrospective cohort study

Traumatic brain injuries (TBI) are one of the leading causes of morbidity and mortality in road traffic accident (RTA) trauma patients. However, the epidemiology of RTA related-TBI has been poorly explored. The main objective was to investigate head injuries pattern, patient characteristics and outcomes. We conducted a multicenter retrospective cohort study including patients of the Rhône RTA registry between 2011 and 2020 who sustained a head injury. Injury characteristics and severities were reported according to the Abbreviated Injury Scale (AIS). Descriptive statistical analyses were performed to characterize the cohort and describe injury patterns. During the study period, the registry included a total of 83,687 patients, of whom 15,373 (18.4%) had sustained at least one head injury AIS ≥ 1. Among those, 61.5% (n = 9,450) were male and the predominant age group was 20-49 years (n = 8,521, 55.4%). A total of 8.9% of patients sustained a serious-to-critical head injuriesinjury (AIS ≥ 3), 24.8% needed hospital admission and 2.5% died. Most patient were car occupants (n = 7,291, 47.4%). The most common injury types were mild TBI without loss of consciousness (59.7%), scalp injuries (25.1%) and mild TBI with loss of consciousness (15.1%). Subarachnoid hemorrhage was the most prevalent type of intracranial hemorrhage (4.1%). The most common concomitant extracranial injuries involved the extremities (n = 8,220, 38.7%) and serious-to-critical extracranial injuries(maximum AIS ≥ 3) mostly affected the thorax (n = 843, 43.7%). Significant variations in the types of head injuries were observed across different user groups with motorcyclists and pedestrians representing the most severely head-injured groups. The present study found that one in five RTA patients sustained a head injury with approximatively 10% of head injuries being serious-to-critical. Incidence and injury patterns vary across user categories. Serious-to-critical head injurieswere predominantly observed among pedestrians, motorcyclists and cyclists, indicating their heightened vulnerability and the need for targeted public health interventions.