Daily cannabis use associated with 50% lower odds of daily illicit opioid use among people with chronic pain
Among people who use drugs and report chronic pain, daily cannabis use was independently associated with half the odds of daily illicit opioid use over a 3.5-year period.
Quick Facts
What This Study Found
After adjusting for demographics, substance use, and health factors, daily cannabis use was associated with significantly lower odds of daily illicit opioid use (adjusted OR 0.50, 95% CI 0.34-0.74, p < 0.001). The most common therapeutic reasons for cannabis use were pain (36%), sleep (35%), stress (31%), and nausea (30%).
Key Numbers
1,152 participants; 40% reported daily illicit opioid use; 36% reported daily cannabis use; adjusted OR 0.50 (95% CI 0.34-0.74); median age 49.3 years; 36.8% women.
How They Did This
Longitudinal analysis of 1,152 people who use drugs with chronic pain from two prospective Vancouver cohorts (June 2014-December 2017), using generalized linear mixed-effects models with 6-month follow-up periods.
Why This Research Matters
This is rare individual-level longitudinal data supporting the population-level finding that cannabis access may reduce opioid use. Most prior evidence was ecological (state-level), making individual associations difficult to establish.
The Bigger Picture
While ecological studies have shown lower opioid overdose rates in medical cannabis states, individual-level data has been largely missing. This study fills that gap, though it involves a specific population (people who already use drugs) rather than the general public.
What This Study Doesn't Tell Us
Self-reported substance use and pain. Population is people who already use drugs, not representative of all chronic pain patients. No data on cannabis preparations, dosages, or administration methods. Observational design cannot prove causation.
Questions This Raises
- ?Does this substitution effect hold for people who are not already using illicit drugs?
- ?What cannabis preparations and doses are most effective for opioid substitution?
Trust & Context
- Key Stat:
- OR 0.50 for daily opioid use
- Evidence Grade:
- Moderate: longitudinal cohort with adjusted analysis, but observational design and specific population.
- Study Age:
- Published in 2019.
- Original Title:
- Frequency of cannabis and illicit opioid use among people who use drugs and report chronic pain: A longitudinal analysis.
- Published In:
- PLoS medicine, 16(11), e1002967 (2019)
- Authors:
- Lake, Stephanie(16), Walsh, Zach(19), Kerr, Thomas(11), Cooper, Ziva D, Buxton, Jane, Wood, Evan, Ware, Mark A, Milloy, M J
- Database ID:
- RTHC-02123
Evidence Hierarchy
Follows a group of people over time to track how outcomes develop.
What do these levels mean? →Frequently Asked Questions
Does cannabis replace opioids for pain?
In this study of people who use drugs with chronic pain, daily cannabis users had half the odds of daily illicit opioid use, but the study cannot prove cannabis caused the reduction.
Why did participants use cannabis?
The most common reasons were pain (36%), sleep (35%), stress (31%), and nausea (30%).
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Cite This Study
https://rethinkthc.com/research/RTHC-02123APA
Lake, Stephanie; Walsh, Zach; Kerr, Thomas; Cooper, Ziva D; Buxton, Jane; Wood, Evan; Ware, Mark A; Milloy, M J. (2019). Frequency of cannabis and illicit opioid use among people who use drugs and report chronic pain: A longitudinal analysis.. PLoS medicine, 16(11), e1002967. https://doi.org/10.1371/journal.pmed.1002967
MLA
Lake, Stephanie, et al. "Frequency of cannabis and illicit opioid use among people who use drugs and report chronic pain: A longitudinal analysis.." PLoS medicine, 2019. https://doi.org/10.1371/journal.pmed.1002967
RethinkTHC
RethinkTHC Research Database. "Frequency of cannabis and illicit opioid use among people wh..." RTHC-02123. Retrieved from https://rethinkthc.com/research/lake-2019-frequency-of-cannabis-and
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.