Traffic injury ED visits involving cannabis grow over recent years
Key takeaways:
- The rate of ED visits for traffic injuries that involved cannabis has gone up between 2010 and 2021 in Ontario, Canada.
- Commercialization of cannabis may be a contributing factor to this increase.
From 2010 to 2021 — a period during which cannabis legalization and commercialization took place in Canada — ED visits for traffic injury involving cannabis have occurred more often, according to results published in JAMA Network Open.
“Our data suggest that ED visits for traffic injuries with documented cannabis involvement have been increasing steadily over time in Ontario,” Daniel T. Myran, MD, MPH, CCFP, FRCPC, assistant professor and lecturer at University of Ottawa, told Healio. “Legalizing cannabis and particularly allowing a widespread commercial market with expanded stores may have accelerated this trend.”
Myran explained that, although these were rare events, there is a potential for further increases in cannabis-impaired driving based on the data.
“Injuries with cannabis involvement were much more severe than injuries without — with higher rates of hospital and ICU admission,” he said.
In a cross-sectional study conducted in Ontario, Canada, Myran and colleagues analyzed 947,604 traffic injury ED visits among individuals aged 16 years and older to compare the prevalence of visits related to cannabis before it was legalized (January 2010 to September 2018), when it was legalized with product and retail store restrictions (October 2018 to February 2020) and when it was commercialized/available in more stores (March 2020 to December 2021) using season and time-adjusted quasi-Poisson models.
Findings
Cannabis was involved in 426 (0.04%) traffic injury ED visits among 418 individuals (mean age, 30.6 years; 25.6% aged 16 to 21 years; 78.9% boys). In the 2 years prior to this visit, 27% of these individuals visited the ED or were hospitalized for substance use.
Harmful cannabis use was indicated as the cause of these ED visits for 41.1% of individuals. Other causes of these visits included acute intoxication in 33.1% of individuals and cannabis dependence/withdrawal in 9.6% of individuals.
Of the 426 visits that involved cannabis, 178 (41.8%) also involved alcohol.
“Co-use of alcohol and cannabis, a particularly risky mix, was very common, highlighting a need for further education and intervention,” Myran told Healio.
From 2010 to 2021, researchers found that the annual rate of traffic injury ED visits involving cannabis went up from 0.18 visits per 1,000 total motor vehicle collisions to 1.01 visits per 1,000 collisions, signaling a 475.3% increase.
In comparison, alcohol was involved in 7,564 (0.8%) ED visits, with the annual rate of traffic injury ED visits involving alcohol increasing 9.4% from 8.03 visits per 1,000 collisions to 8.79 visits per 1,000 collisions from 2010 to 2021.
“The scale of the increase over time in cannabis-involvement in traffic injuries was quite surprising as was the very high proportion of traffic injuries that had both cannabis and alcohol involvement,” Myran told Healio.
Adjusted analyses
Compared with the time period before cannabis was legalized, researchers found that legalization with restrictions raised the quarterly rate of cannabis-related traffic injury ED visits by 94% (seasonally adjusted rate ratio [aRR] = 1.94; 95% CI, 1.37-2.75).
An even larger increase in this rate was observed from prelegalization to when cannabis was commercialized/the COVID-19 pandemic began (seasonally aRR = 3.23; 95% CI, 2.42-4.33). Unlike the legalization with restrictions period, researchers found that the commercialization period continued to be linked to high quarterly rates of cannabis-related traffic injury ED visits after accounting for season and time trends prior to cannabis legalization (time and seasonally aRR = 1.74; 95% CI, 1.03-2.96).
Several demographics/clinical characteristics raised the odds for a traffic injury ED visit that involved cannabis: a previous ED visit related to cannabis (adjusted OR = 8.03; 95% CI, 5.85-11.02), age between 16 to 18 years (aOR = 3.76; 95% CI, 2.54-5.56) and between 19 to 21 years (aOR = 4.67; 95% CI, 3.27-6.67), male sex (aOR = 3.38; 95% CI, 2.66-4.29) and residence in a poor income neighborhood (aOR = 1.92; 95% CI, 1.39-2.67).
Researchers observed some overlap in predictors of traffic injury ED visits that involved alcohol, including a previous ED visit related to alcohol (aOR = 14.99; 95% CI, 13.97-16.08), male sex (aOR = 3.27; 95% CI, 3.08-3.47) and residence in a poor income neighborhood (aOR = 1.53; 95% CI, 1.42-1.65).
“In future studies, we plan to continue to track long-term changes in cannabis involvement in traffic injuries as the legal market continues to evolve in Canada,” Myran told Healio. “Most of our post-legalization period overlapped with the COVID-19 pandemic during which overall mobility and care use declined substantially. The most important area of research will be understanding what happened to traffic injury ED visits after the COVID-19 pandemic when traffic levels return to pre-pandemic patterns.”