More Drivers Test Positive for Marijuana After Medical Legalization in Pennsylvania
After Pennsylvania legalized medical marijuana in 2016, trauma centers saw a significant increase in motor vehicle crash victims testing positive for marijuana, with these patients being younger and having longer hospital stays.
Quick Facts
What This Study Found
Following medical marijuana legalization, marijuana positivity among MVC trauma patients increased significantly (p<0.0001), with marijuana-positive patients having longer hospital stays (+2 days) and higher rates of polysubstance use compared to marijuana-negative patients.
Key Numbers
10,517 trauma patients; pre vs. post-legalization comparison over 16 years; marijuana-positive patients had +2 days longer hospital stays; significant increase in marijuana detection post-legalization (p<0.0001); higher polysubstance use (p<0.001)
How They Did This
Retrospective case-control study of 10,517 trauma patients from MVCs at a Pennsylvania trauma center from 2008-2024, comparing pre-legalization (2008-2016) and post-legalization (2016-2024) groups using Chi-square tests.
Why This Research Matters
This large-scale real-world data from a single trauma center provides evidence that medical marijuana legalization correlates with increased marijuana-positive driving, informing road safety policy discussions.
The Bigger Picture
As more states legalize cannabis, understanding its impact on traffic safety becomes critical — this study adds to evidence that legalization increases detection of cannabis among crash-involved drivers.
What This Study Doesn't Tell Us
Single trauma center limits generalizability; correlation not causation; toxicology testing may have changed over the study period; positive test doesn't confirm impairment at time of crash; medical marijuana law may coincide with other policy changes.
Questions This Raises
- ?Does recreational legalization show an even larger effect?
- ?Are the longer hospital stays due to marijuana itself or associated polysubstance use?
- ?How do impairment levels compare to alcohol-impaired drivers?
Trust & Context
- Key Stat:
- Evidence Grade:
- Large sample retrospective study with clear pre/post comparison, but limited by single center, potential confounders, and inability to confirm impairment from positive test alone.
- Study Age:
- Published 2026; covers data through March 2024.
- Original Title:
- Characteristics of trauma patients involved in motor vehicle collisions before and after legalization of medical marijuana in Pennsylvania.
- Published In:
- The American journal of emergency medicine, 99, 296-300 (2026)
- Authors:
- Gimbel, Kirsten, Marco, Catherine A(2)
- Database ID:
- RTHC-08280
Evidence Hierarchy
Frequently Asked Questions
Did marijuana-related car crashes increase after legalization?
This Pennsylvania study found a significant increase in marijuana-positive MVC trauma patients after medical marijuana legalization in 2016, though a positive test alone doesn't prove marijuana caused the crash.
Are marijuana-positive crash victims more severely injured?
They had longer hospital stays (+2 days) and higher rates of polysubstance use, but were more often discharged home, suggesting a complex relationship between marijuana positivity and crash severity.
Read More on RethinkTHC
Cite This Study
https://rethinkthc.com/research/RTHC-08280APA
Gimbel, Kirsten; Marco, Catherine A. (2026). Characteristics of trauma patients involved in motor vehicle collisions before and after legalization of medical marijuana in Pennsylvania.. The American journal of emergency medicine, 99, 296-300. https://doi.org/10.1016/j.ajem.2025.10.008
MLA
Gimbel, Kirsten, et al. "Characteristics of trauma patients involved in motor vehicle collisions before and after legalization of medical marijuana in Pennsylvania.." The American journal of emergency medicine, 2026. https://doi.org/10.1016/j.ajem.2025.10.008
RethinkTHC
RethinkTHC Research Database. "Characteristics of trauma patients involved in motor vehicle..." RTHC-08280. Retrieved from https://rethinkthc.com/research/gimbel-2026-characteristics-of-trauma-patients
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.