Motor Vehicle Collision Trends in Ontario’s Young and Novice Drivers: A Retrospective Cohort Study from 2001-2006

摘要

Purpose: The aim of this analysis is to estimate and compare both crude rates and adjustedrelative risks of motor vehicle collision in young and novice drivers in Ontario. We willinvestigate whether differences in the magnitude of the crude rates or adjusted risks can beaccounted for by factors, such as: license class, gender, age, and suspension or convictionhistory.Methods: A retrospective cohort design was employed. Driver records for those with G1(beginner), G2 (intermediate) or G (full) licenses in Ontario, aged 16-24 on January 1, 2001were selected from an Ontario Ministry of Transportation (MTO) database. The cohort wasfollowed from January 1, 2001 to December 31, 2006. The number of police-reported collisionsincurred during this interval by individuals in each license class was enumerated. Rates ofcollisions (per 100,000 driver-days licensed) were calculated by license class at time of event,gender, age at study start date, and suspension/conviction history. Negative binomial regressionwas used to assess the adjusted impact of license class, gender, age and suspension orconviction history on the risk of collisions. All summary statistics and regression models wereestimated following a reclassification of the outcome variable to document whether the policeofficer reporting the collision classified the driver as “driving properly” versus “not drivingproperly”.Results: At the study start date, cases included 3,621 beginner drivers (1%), 133,515intermediate drivers (48%) and 142,245 full class drivers (51%). Slightly more males (54%)were observed than females (46%). At the beginning of the study, 8% of cases were 16-17years of age, 52% of cases were 18-20 years of age and 40% of cases were 21-24 years ofage. The total number of collisions incurred over the six years of observation was 164,242. Theoverall rate of collisions was 26.84 per 100,000 days licensed (95% CI: 26.64-27.04). The rateof collisions in beginner, intermediate and full license class drivers was 3.72, 36.64 and 26.28,respectively. Males had higher rates of collisions than females. Younger persons also had higher rates of collision. Those with a history of either suspension or conviction had higher ratesof collision than drivers who had never had their motor vehicle license suspended or beenconvicted of a traffic violation. Adjusted relative risks from the multivariate negative binomialmodels were in concordance with the trends observed in the crude rates.Conclusions: Graduated driver licensing (GDL) programs are designed to prepare individualsto adequately handle the risks of driving. Beginner drivers were observed to have a markedlylower rate of collisions compared to intermediate drivers. The lower rates of collisions observedin beginner drivers are likely a result of the GDL restrictions placed on this license class. Whenmany of these restrictions are removed, the rates of collisions increase in intermediate driversand surpass rates for fully licensed drivers. This finding suggests that enhanced exposure,practice and training is required for beginner license class drivers or that a different subset ofrestrictions may need to be considered for intermediate license class drivers.