OBJECTIVES: To determine if changes to the Ontario Highway Traffic Act (OHTA) in 2009 and 2010 had an effect on the proportion of alcohol-related motor vehicle collisions (MVCs) presenting to a trauma centre over a 10-year period.

METHODS: A retrospective review of the trauma registry at a Level I trauma centre in southwestern Ontario was undertaken. The trauma registry is a database of all trauma patients with an injury severity score (ISS) ≥12 and/or who had trauma team activation. Descriptive statistics were calculated. Interrupted time series analyses with ARIMA modeling were performed on quarterly data from 2004-2013.

RESULTS: A total of 377 drivers with a detectable serum ethanol concentration (SEC) were treated at our trauma centre over the 10-year period, representing 21% of all MVCs. The majority (330; 88%) were male. The median age was 31 years, median SEC was 35.3 mmol/L, and median ISS was 21. A total of 29 (7.7%) drinking drivers died from their injuries after arriving to hospital. There was no change in the proportion of drinking drivers after the 2009 amendment, but there was a significant decline in the average SEC of drinking drivers after changes to the law. There was no difference in the proportion of drinking drivers ≤21 years after introduction of the 2010 amendment for young and novice drivers.

CONCLUSIONS: There was a significance decline in the average SEC of all drinking drivers after the 2009 OHTA amendment, suggesting that legislative amendments may have an impact on drinking before driving behaviour.