TRAFFIC SAFETY FACTS
Drug and Alcohol Crash Risk
This study of crash risk found a statistically significant increase in unadjusted crash risk for drivers who tested positive for use of illegal drugs (1.21 times), and THC specifically (1.25 times). However, analyses incorporating adjustments for age, gender, ethnicity, and alcohol concentration level did not show a significant increase in levels of crash risk associated with the presence of drugs. This finding indicates that these other variables (age, gender ethnicity and alcohol use) were highly correlated with drug use and account for much of the increased risk associated with the use of illegal drugs and with THC.
This analysis shows that the significant increased risk of crash involvement associated with THC and illegal drugs is not found after adjusting for these demographic variables. This finding suggests that these demographic variables may have co-varied with drug use and accounted for most of the increased crash risk. For example, if the THC-positive drivers were predominantly young males, their apparent crash risk may have been related to age and gender rather than use of THC.
View attachment 43006
Compton, R. P. & Berning, A. (2015, February). Drug and alcohol
crash risk. (Traffic Safety Facts Research Note, Report
No. DOT HS 812 117). Washington, DC: National Highway
Traffic Safety Administration.
Shocking Results Drug and Alcohol Crash Risk Study A Must Read