Frequent cannabis use was linked to 71% fewer opioid overdoses among methadone patients
Among 446 patients in methadone treatment, those who used cannabis frequently had a 71% lower likelihood of reporting a nonfatal opioid overdose in the past year.
Quick Facts
What This Study Found
Nonfatal opioid overdose prevalence was 3% among frequent cannabis users vs 9% among infrequent/non-users (p=0.02). After controlling for demographic and clinical factors, frequent cannabis users had 71% lower likelihood of overdose (adjusted RR=0.29, 95% CI 0.10-0.80).
Key Numbers
446 participants; 35% frequent cannabis users; 7% reported nonfatal overdose; 3% overdose among frequent users vs 9% among infrequent; adjusted RR=0.29 (71% reduction); 95% CI 0.10-0.80
How They Did This
Cross-sectional survey of 446 individuals enrolled in four methadone maintenance treatment clinics in Washington State and southern New England, comparing frequent (weekly+) vs infrequent cannabis users.
Why This Research Matters
Opioid overdose remains a leading cause of death. If cannabis use genuinely reduces overdose risk among people in treatment for opioid use disorder, it could inform harm reduction strategies.
The Bigger Picture
This individual-level finding complements ecological studies showing lower overdose rates in states with cannabis laws, providing preliminary evidence that the association may operate at the individual patient level.
What This Study Doesn't Tell Us
Cross-sectional design cannot establish causation. Self-reported cannabis use and overdose. Convenience sample may not represent all MMT patients. Possible confounders not captured. Reverse causation possible (those at higher overdose risk may avoid cannabis).
Questions This Raises
- ?Is cannabis providing pain relief that reduces supplemental opioid use?
- ?Or does frequent cannabis use identify a subpopulation with different risk factors?
- ?Would a prospective study confirm this protective association?
Trust & Context
- Key Stat:
- 71% lower likelihood of nonfatal opioid overdose among frequent cannabis users
- Evidence Grade:
- Cross-sectional survey with significant association but inability to establish causation
- Study Age:
- Published in 2021. The relationship between cannabis and opioid outcomes remains actively debated.
- Original Title:
- Cannabis Use and Nonfatal Opioid Overdose among Patients Enrolled in Methadone Maintenance Treatment.
- Published In:
- Substance use & misuse, 56(5), 697-703 (2021)
- Authors:
- Bryson, William C, Morasco, Benjamin J(6), Cotton, Brandi P, Thielke, Stephen M
- Database ID:
- RTHC-03029
Evidence Hierarchy
A snapshot of a population at one point in time.
What do these levels mean? →Frequently Asked Questions
Can cannabis reduce opioid overdose risk?
In this study of methadone patients, frequent cannabis users had 71% lower odds of nonfatal overdose. However, the cross-sectional design cannot prove cannabis caused this reduction, and other explanations are possible.
Should opioid treatment programs encourage cannabis use?
The authors caution against causal interpretation. While the association is noteworthy, additional prospective studies are needed before cannabis could be considered part of a harm reduction strategy for opioid use disorder.
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Cite This Study
https://rethinkthc.com/research/RTHC-03029APA
Bryson, William C; Morasco, Benjamin J; Cotton, Brandi P; Thielke, Stephen M. (2021). Cannabis Use and Nonfatal Opioid Overdose among Patients Enrolled in Methadone Maintenance Treatment.. Substance use & misuse, 56(5), 697-703. https://doi.org/10.1080/10826084.2021.1892137
MLA
Bryson, William C, et al. "Cannabis Use and Nonfatal Opioid Overdose among Patients Enrolled in Methadone Maintenance Treatment.." Substance use & misuse, 2021. https://doi.org/10.1080/10826084.2021.1892137
RethinkTHC
RethinkTHC Research Database. "Cannabis Use and Nonfatal Opioid Overdose among Patients Enr..." RTHC-03029. Retrieved from https://rethinkthc.com/research/bryson-2021-cannabis-use-and-nonfatal
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.