The impact of minimum unit pricing on traumatic brain injury in Scotland: a retrospective cohort study of routine national data.

Background: Traumatic brain injury (TBI) is a common cause of disability and mortality and is associated with alcohol consumption. On 1st May 2018, the Scottish Government introduced Minimum Unit Pricing (MUP) legislation which set the floor price at which alcohol can be sold to 50 pence per unit. While MUP has led to a 7.6% decrease in off trade alcohol purchases, there are limited studies investigating the clinical impact of this legislation. This study aims to explore the impact of MUP on traumatic brain injury in Scotland. Methods: Retrospective cohort study using routinely collected national data collated by the Scottish Trauma Audit Group. Data were requested for all TBI incidents from 1st May to 31st December for both 2017 and 2018. Primary outcome was alcohol-related TBI. Secondary outcomes were injury mechanism, injury severity, clinical course, and short-term mortality. Analysis was conducted using multiple regression models adjusted for age, sex, season, and deprivation. Results: A total of 1166 patients (66% male, and 46% in the 60-79-year bracket) were identified. Alcohol-related TBI was evident in 184 of 509 (36%) patients before MUP and in 239 of 657 (36%) patients injured after its implementation ( p  = 0.638). Further, there was no change in injury mechanism, injury severity, hospital course and short-term mortality of TBI after MUP. Conclusions: MUP has not resulted in a change in alcohol-related TBI nor in the mechanism and severity of TBI. Limitations in two-point analysis mean that findings should be interpreted with caution and further studies investigating the clinical outcomes of MUP must be conducted.