LO66: The effect of Alberta’s new impaired driving legislation on motor vehicle-related trauma

Abstract

Introduction: Motor vehicle collisions (MVCs) resulting in injuries and death disproportionately involve impaired drivers. Those under the influence of alcohol also have a higher rate of presentation and admission to hospital for traumatic injuries. In an attempt to decrease impaired driving and alcohol-related MVCs and injuries, the government of Alberta introduced stricter impaired driving legislation in the summer of 2012. It has yet to be determined what impact this new legislation has had on traumatic injuries secondary to MVCs and alcohol impairment. The objective of this study was to assess the relationship between the implementation of the new legislation and the proportion of alcohol-related MVC trauma presenting to the emergency department of a Level I Trauma Centre. Methods: A retrospective single centre cross-sectional chart review examining adult patients presenting to the ED of a major trauma centre who: a) require trauma team activation or consultation and b) have a MVC related injury. Of those charts meeting these criteria, the proportion of patients with positive blood alcohol concentration (BAC) was compared between the year before and the four years after implementation of the new legislation. Patients were identified using electronic medical record logs. We compared the proportion of impaired drivers by year using the SPSS software package and conducted an interrupted time series analysis in order to determine whether the implementation of the law directly affected the measured outcomes. Results: 1470 total MVC related trauma patients were identified during the study period (468 prior to legislation implementation [2010-2012] and 1002 after [2012-2016]). The proportion of drivers with BAC defined as legally impaired decreased significantly over this time period (p=0.003). Based on preliminary interrupted time series analysis we cannot conclude that the implementation of the new laws led to this significant change (p=0.524). When analyzing drivers between 16 to 25 years old, we noted a non-significant but notable decrease in the proportion of impaired drivers from 45.9% in 2011 to 21.1% in 2016 (p=0.173). Conclusion: While an impact was not seen immediately following the implementation of Alberta’s new impaired driving legislation, the proportion of impaired drivers requiring trauma team activation has decreased significantly since enactment of the new legislation from 28.9% in 2011 to 16.9% in 2016. However, based on interrupted time series analysis we cannot conclude the new legislation independently influenced this change. The impact of other factors including public education, societal preferences and generational changes cannot be excluded. There continues to be a dramatic decrease in the proportion of impaired drivers presenting with MVC related trauma under 25 years old This has not yet reached statistical significance probably due to small sample size but the trend is most prominent in this age group.