Daily Cannabis Use Was Linked to Better Retention in Opioid Treatment Programs
People who used cannabis daily had 21% greater odds of staying in opioid agonist treatment (methadone or buprenorphine) compared to less-than-daily users, in a large cohort followed for nearly 7 years.
Quick Facts
What This Study Found
Daily cannabis use was positively associated with retention in OAT (adjusted OR 1.21, 95% CI 1.04-1.41). Compared to non-users, daily users had increased odds of retention (aOR 1.20, 95% CI 1.02-1.43), but less-than-daily users did not (aOR 1.00, 95% CI 0.87-1.14), suggesting a dose-response relationship.
Key Numbers
820 participants, 57.8% men, 32.2% HIV-positive. Median follow-up 81 months. Daily cannabis use: aOR 1.21 (95% CI 1.04-1.41) for treatment retention. Less-than-daily use showed no association.
How They Did This
Longitudinal analysis of 820 participants from two community-recruited prospective cohorts of people who use illicit drugs in Vancouver, Canada. Followed for a median of 81 months with 6-month assessment periods.
Why This Research Matters
Retention in opioid agonist treatment is the single strongest predictor of reduced opioid-related morbidity and mortality. If daily cannabis use supports treatment retention, it could be an important harm reduction consideration during the opioid crisis.
The Bigger Picture
While some treatment providers worry about cannabis use during opioid treatment, this study suggests daily cannabis use may actually support treatment engagement. This challenges policies that penalize cannabis use in opioid treatment programs.
What This Study Doesn't Tell Us
Observational study cannot prove causation. Self-reported cannabis use. Vancouver population may not generalize. Unmeasured confounders possible. Cannot determine why cannabis use might support retention.
Questions This Raises
- ?What mechanism explains the association - does cannabis reduce withdrawal symptoms, cravings, or anxiety?
- ?Should opioid treatment programs adopt more permissive cannabis policies?
- ?Would this finding replicate in randomized trials?
Trust & Context
- Key Stat:
- Daily cannabis use was associated with 21% greater odds of retention in opioid treatment (aOR 1.21, 95% CI 1.04-1.41).
- Evidence Grade:
- Moderate - large prospective cohort with long follow-up and appropriate adjustments, but observational.
- Study Age:
- Published in 2018. Data collected 1996-2016 in Vancouver.
- Original Title:
- High-intensity cannabis use is associated with retention in opioid agonist treatment: a longitudinal analysis.
- Published In:
- Addiction (Abingdon, England), 113(12), 2250-2258 (2018)
- Authors:
- Socías, Maria Eugenia, Wood, Evan(8), Lake, Stephanie(16), Nolan, Seonaid, Fairbairn, Nadia, Hayashi, Kanna, Shulha, Hennady P, Liu, Seagle, Kerr, Thomas, Milloy, M-J
- Database ID:
- RTHC-01841
Evidence Hierarchy
Follows a group of people over time to track how outcomes develop.
What do these levels mean? →Frequently Asked Questions
Does cannabis use help people stay in opioid treatment?
This large study found daily cannabis users had 21% greater odds of remaining in opioid agonist treatment. Interestingly, less-than-daily use showed no benefit, suggesting only regular cannabis use was associated with improved retention.
Should opioid treatment programs allow cannabis use?
This study suggests daily cannabis use during opioid treatment may support retention rather than hinder it. Since treatment retention is the strongest predictor of reduced opioid-related death, policies that penalize cannabis use in these programs may need reconsideration.
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Cite This Study
https://rethinkthc.com/research/RTHC-01841APA
Socías, Maria Eugenia; Wood, Evan; Lake, Stephanie; Nolan, Seonaid; Fairbairn, Nadia; Hayashi, Kanna; Shulha, Hennady P; Liu, Seagle; Kerr, Thomas; Milloy, M-J. (2018). High-intensity cannabis use is associated with retention in opioid agonist treatment: a longitudinal analysis.. Addiction (Abingdon, England), 113(12), 2250-2258. https://doi.org/10.1111/add.14398
MLA
Socías, Maria Eugenia, et al. "High-intensity cannabis use is associated with retention in opioid agonist treatment: a longitudinal analysis.." Addiction (Abingdon, 2018. https://doi.org/10.1111/add.14398
RethinkTHC
RethinkTHC Research Database. "High-intensity cannabis use is associated with retention in ..." RTHC-01841. Retrieved from https://rethinkthc.com/research/socias-2018-highintensity-cannabis-use-is
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.