About 1 in 4 injured young drivers in Arizona tested positive for alcohol, THC, or both
Among 5,069 injured drivers aged 16-20 at Arizona trauma centers, 19% tested positive for alcohol and 30% tested positive for THC, with substance-positive drivers less likely to wear seat belts or helmets.
Quick Facts
What This Study Found
Of drivers with BAC results, 19% tested positive (82% of those at or above 0.08 g/dL). Of drivers with THC results, 30% tested positive. American Indians had the highest THC-positive rates (38%) and highest dual positive rates (28%). Substance-positive drivers were less likely to wear seat belts or helmets.
Key Numbers
5,069 injured drivers. 19% BAC-positive (82% at 0.08+). 30% THC-positive. American Indians: 38% THC-positive, 28% dual positive. Annual injured drivers declined 41% over the study period.
How They Did This
Retrospective analysis of 5,069 injured drivers aged 16-20 evaluated at Arizona level 1 trauma centers (2008-2014) using the Arizona State Trauma Registry. Descriptive analysis of BAC and THC test results by demographics and safety behaviors.
Why This Research Matters
The high rate of THC positivity (30%) among injured young drivers, combined with reduced safety behavior, suggests cannabis-impaired driving is a substantial contributor to youth traffic injuries.
The Bigger Picture
While alcohol-impaired driving among youth has received decades of public health attention, THC-impaired driving is an emerging concern. The higher THC-positive rate (30%) than alcohol-positive rate (19%) among tested drivers is notable.
What This Study Doesn't Tell Us
Only injured drivers at level 1 trauma centers, not representative of all young drivers. Not all drivers were tested for both substances. THC presence indicates recent use but not necessarily impairment at time of crash.
Questions This Raises
- ?Are cannabis-positive crashes increasing over time?
- ?Do cannabis and alcohol have synergistic effects on crash risk?
- ?Would targeted prevention for high-risk populations (American Indian communities) reduce these disparities?
Trust & Context
- Key Stat:
- 30% of tested injured young drivers were THC-positive
- Evidence Grade:
- Moderate: seven-year trauma registry data with biological testing, but limited to one state and level 1 trauma centers.
- Study Age:
- Published in 2019.
- Original Title:
- Alcohol and marijuana use among young injured drivers in Arizona, 2008-2014.
- Published In:
- Traffic injury prevention, 20(1), 9-14 (2019)
- Database ID:
- RTHC-02294
Evidence Hierarchy
Looks back at existing records to find patterns.
What do these levels mean? →Frequently Asked Questions
Does THC-positive mean the driver was impaired?
Not necessarily. THC can remain detectable in blood for hours to days after use. However, the high rate among injured drivers compared to general population estimates suggests an association with crash risk.
Why were American Indian drivers disproportionately affected?
The study documented the disparity but did not investigate causes. Socioeconomic factors, access to treatment, and reservation-specific alcohol/drug policies may all contribute.
Read More on RethinkTHC
Cite This Study
https://rethinkthc.com/research/RTHC-02294APA
Shults, Ruth A; Jones, Jefferson M; Komatsu, Kenneth K; Sauber-Schatz, Erin K. (2019). Alcohol and marijuana use among young injured drivers in Arizona, 2008-2014.. Traffic injury prevention, 20(1), 9-14. https://doi.org/10.1080/15389588.2018.1527032
MLA
Shults, Ruth A, et al. "Alcohol and marijuana use among young injured drivers in Arizona, 2008-2014.." Traffic injury prevention, 2019. https://doi.org/10.1080/15389588.2018.1527032
RethinkTHC
RethinkTHC Research Database. "Alcohol and marijuana use among young injured drivers in Ari..." RTHC-02294. Retrieved from https://rethinkthc.com/research/shults-2019-alcohol-and-marijuana-use
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.