Legal Cannabis States Reported Fewer Cannabis Use Disorder Diagnoses in Treat-and-Release ER Visits
A 2023 study found that emergency-department visits in Colorado and Oregon were less likely to include a documented cannabis use disorder (CUD) diagnosis than comparable visits in Maryland and Rhode Island. The result describes an association in medical records—not proof that recreational cannabis legalization reduces cannabis-related problems.
Published in Preventive Medicine Reports, the study analyzed 17,434,655 “treat and release” emergency-department visits recorded between 2017 and 2020. The researchers used four years of data from Colorado, Oregon and Maryland, and three years of data from Rhode Island, where 2020 data were not included. During the study period, recreational cannabis was legal in Colorado and Oregon but not in Maryland or Rhode Island.
The researchers identified visits that included a diagnosis of cannabis abuse, dependence or CUD, then used multivariable logistic regression to account for patient and state-level characteristics. Overall, 0.63% of the visits included a CUD diagnosis. The state-level rates were 0.39% in Colorado, 0.35% in Oregon, 1.03% in Maryland and 0.79% in Rhode Island.
After adjustment, visits in the recreationally legal states had about half the odds of carrying a CUD diagnosis compared with visits in the states where recreational cannabis remained prohibited. The adjusted odds ratio was 0.49, with a 95% confidence interval of 0.47 to 0.52.
That finding does not establish that legalization caused lower rates of cannabis use disorder. The study was observational and compared four states rather than randomly assigning jurisdictions to different cannabis policies. It also examined diagnoses recorded during emergency visits—not the underlying prevalence of CUD in the population, the number of cannabis-related emergencies overall, or visits that resulted in hospital admission.
The authors suggested that declining stigma after legalization could influence clinical documentation. Health-care providers or patients may be more comfortable discussing cannabis in legal states, while clinicians could also be less likely to identify or code cannabis use as problematic. Differences among the states—including demographics, health-care systems, coding practices and other policies—could also have affected the results.
The data came from the Healthcare Cost and Utilization Project’s State Emergency Department Databases, which capture emergency-department encounters that do not result in admission. That design makes the findings useful for studying outpatient emergency care, but it limits how broadly they can be applied to all hospital patients or to the general population.
The study also should not be read as settling the broader debate over cannabis legalization. Research on cannabis use and CUD has produced mixed results across age groups, data sources and study designs. For example, a longitudinal analysis of adolescents in Oregon, New York and Washington found no significant change in the likelihood or frequency of self-reported cannabis use after legalization, while other studies have reported increases in cannabis use or CUD among some adult or youth groups. A 2024 systematic review and meta-analysis concluded that recreational-cannabis laws were associated with a modest increase in past-month cannabis use among U.S. youth, while emphasizing the need for further research.
The emergency-department study therefore offers a narrower conclusion: during the years examined, CUD diagnoses were recorded less often in treat-and-release emergency visits in two states with recreational legalization than in two states without it. Whether that difference reflects changes in problematic use, differences in who seeks emergency care, or changes in diagnosis and documentation remains uncertain.
