Cohort of People With Non-Medical Opioid Use Did Not Substitute Cannabis for Opioids

Studies reporting an association between medical cannabis laws and decreased rates of opioid-related overdose have raised the question of whether individuals at risk of opioid-related overdose substitute cannabis for non-prescription opioids, thereby reducing their overdose risk. This exploratory study used a within-person analysis to examine the association between cannabis use and non-medical opioid use in a cohort of 211 adults with non-medical opioid use (mean age 43 years, 64% male, 41% white, 78% unmarried, 80% unemployed, 67% moderate-to-severe opioid use disorder [OUD], 50% at least moderate pain over last 30 days).

• Participants completed daily interactive voice response questions about cannabis and opioid use for a 90-day period, with a 70% completion rate.
• Participants reported opioid use without cannabis on 15% of days on average, cannabis use without opioids on 15% of days, both cannabis and opioid use on 7% of days, and neither cannabis nor opioid use on 63% of days.
• The adjusted odds of non-medical opioid use was 1.86 on days when cannabis was used, compared with days when cannabis was not used.
• Results did not differ for patients with and without moderate-to-severe pain, and were consistent across gender and OUD severity.

Comments: This study failed to find evidence of substitution of cannabis for non-medical opioids in a cohort at risk for opioid-related overdose. While the study findings are exploratory, they are consistent with growing evidence that goes against the hypothesis that cannabis is being substituted for opioids and is associated with reduced opioid complications.

Joseph Merrill, MD, MPH

Reference: Gorfinkel LR, Stohl M, Greenstein E, et al. Is cannabis being used as a substitute for non-medical opioids by adults with problem substance use in the United States? A within-person analysis. Addiction. 2021;116(5):1113–1121.