Incidence and mortality of acquired brain injury in young Danish adults between 1994 and 2013: a nationwide study

Background: We estimated the annually incidence and mortality of acquired brain injury (ABI) in people aged 15–30 years during 1994–2013. Methods: All Danes with a first-ever hospital diagnosis of ABI, including traumatic brain injury (TBI), encephalopathy, CNS-infection or brain tumour, were identified in the Danish National Patient Register. Incidence rates (IRs) and estimated annual percentage changes (EAPC) were estimated by Poisson regression. Mortality was estimated by the Kaplan–Meier estimator and adjusted hazard ratios (aHR) were computed using Cox regression with 1994–1998. Results: A total of 10,542 individuals were hospitalized with a first-time diagnosis of ABI. The IR for ABI decreased from 63.36 to 33.91/100,000 person-years from 1994 to 2013 [EAPC: −2.78% (95% CI: −3.26 to −2.28)] mainly driven by a decreasing IR of TBI [EAPC: −6.53% (95% CI: –9.57 to –3.39)] during 2007–2013. IRs of brain tumour and CNS infections also decreased significantly. The mortality after ABI tended to be higher during 1999–2013 compared to 1994–1998. For brain tumour, the 1-year mortality decreased significantly [2009–2013 aHR: 0.41 (95% CI: 0.23–0.72)]. Conclusion: Incidence of hospitalisations for ABI and in particular TBI has decreased significantly. Overall, the mortality after ABI has not improved, but the mortality after brain tumour has decreased significantly.