Table 4.

Comparison to previous literature

Previous study			Current study
	Study population	Findings	Findings
Fuller et al, 20094	TARN eligible patients at TARN submitting hospitals (approx. 50% England) between 2003 and 2009.	From the period 2004 onwards as the proportion of patients with TBI transferred and managed in neuroscience centres increased and the risk adjusted mortality rate for TBI fell.	Complete national data for all hospital in England. A reversal in trend in the mortality rate in the 16–64 age group when the second NICE guideline recommending management of patients with severe injuries in specialist centres was introduced.
Marlow et al 24	Patients aged <16 with ICD10 codes indicating head injury admitted to hospitals in England between 2000 and 2011.	Assessed the annual rate of inpatient deaths (all-cause mortality) for patients admitted with ICD10 codes indicating head injury. Found the death rate fell across the time period, but there was only a statistically significant reduction in the death rate after the 2007 NICE head injury guideline.	The inpatient TBI mortality rate (as indicated by coding of death certificates) for patients aged <16 fell from 1998 to 2017 and was unaffected by the introduction of the NICE guidelines.
The Trauma Audit and Research network report: major trauma in older people25	TARN eligible patients at TARN submitting hospitals between 2005 and 2014 (all hospitals in England by 2014)	A large increase in major trauma, including TBI, in patients 65+, disproportionate to UK population demographic changes. Hypothesised due to increased case ascertainment due to more liberal CT imaging.	We found a large increase in the admission rate for TBI in those 65+ from 10 per 100 000 population to 30 per 100 000 population between 2002 and the point the third NICE guideline was introduced in 2014.