Admissions to substance use treatment facilities for cannabis use disorder, 2000-2017: Does legalization matter?

Background And Objectives: A growing number of US states have legalized marijuana use in the past decade. We examined if marijuana legalization is associated with increased marijuana-related admissions to substance use treatment facilities between 2000 and 2017.

Methods: Data from the Treatment Episode Data Set-Admissions were used to examine the relationship between marijuana-related admissions among adults aged ≥18 by year and legalization status (i.e., fully legalized, medical use only [partially legalized], and illegal) (N = 35,457,854). Using interaction analyses, we further examined whether certain patient characteristics were associated with residence in states that legalized marijuana use as compared to those in which marijuana remained illegal.

Results: Overall, the proportion of marijuana-related admissions in states with legalization decreased by 2.3% from 31.7% in 2000-2005 to 29.4% in 2012-2017 (odds ratio [OR], 0.90; 95% confidence intervals [CI], 0.89-0.90) with little difference from states where marijuana use remained illegal, in which marijuana use as any reason for admissions decreased by 0.3% from 39.8% in 2000-2005 to 39.5% in 2012-2017 (OR, 0.99; 95% CI, 0.98-0.99). We did not find any striking patient characteristics (e.g., referral by the police) associated with admissions in states that legalized compared to those that had not.

Discussion And Conclusions: While earlier studies suggested that marijuana legalization is associated with increased levels of use, emergency department visits, and traffic fatalities, our findings suggest that marijuana legalization did not increase marijuana-related treatment use in the United States.

Scientific Significance: This is the first study to examine the association of marijuana legalization with marijuana-related treatment use.