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

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.

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.

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.

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.

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