Incidence rates of paediatric traumatic brain injury in Denmark - the development over three decades: a nationwide, population-based registry study.

BACKGROUND: Paediatric traumatic brain injury (TBI) is a major global health concern and a leading cause of mortality and disability in children. Despite extensive research, knowledge on incidence based on national health registers is scarce. This study aimed to estimate incidence rates (IR) of TBI across all severity levels over three decades in Danish children. METHODS: Through a nationwide, population-based registry study we identified all children aged 0 to < 15 years born in Denmark between 1977 and 2018. Children were included at birth or immigration and followed until their 15th birthday, death, emigration, or December 31st, 2018. Incident TBIs were classified as minimal, mild, moderate, or severe. RESULTS: Among 3,235,391 children, 127,158 had a TBI before age 15 (56.8% male). The overall IR declined over the study period, with a significant reduction from 498.2 (95% CI 491.6-504.9) per 100,000 person-years (pyrs) in 1985-1989 to 336.2 (95% CI 330.4-342.0) in 2015-2018,the lowest rate observed. IRs for mild, moderate, and severe TBI declined to 50.8, 3.5, and 3.5 per 100,000 pyrs, respectively. In contrast, IR of minimal TBI continued to increase over time. Males consistently exhibited higher IRs, although both sexes showed a steady decline after 1999. CONCLUSION: Paediatric TBI incidence in Denmark has declined over three decades, likely reflecting national prevention strategies e.g. traffic regulations. Nevertheless, incidence remains high, particularly among children aged 0 to < 3 years and males. These findings provide essential data to inform public health initiatives, while highlighting the need for injury prevention.