Title

Cannabis-Based Reductions in Opioid-Related Harms: Population-Based Observational Meta-Analysis

Standing

Undergraduate

Type of Proposal

Oral Research Presentation

Challenges Theme

Open Challenge

Your Location

Windsor, Ontario

Faculty

Faculty of Arts, Humanities and Social Sciences

Faculty Sponsor

Dr. Kevin Gorey

Abstract/Description of Original Work

Abstract

Background: There is currently much debate around harms associated with easier access to cannabis. Yet, surveys of medical marijuana patients and recreational users in Canada and the USA observed that they prevalently (25% to 50%) substitute cannabis for alcohol, opioids, and other drugs, suggesting reduced harms. This synthetic study focused on arguably the most harmful substance opioids, as the growing toll of opioid-related morbidity and mortality requires harm reduction-based interventions.

Methods: Broad keyword searches of interdisciplinary research databases between 2010 and 2020 retrieved 11 studies. Their outcomes were synthesized with a sample-weighted meta-analysis that compared opioid-related outcomes before and after marijuana legalization in states that legalized marijuana versus those that had not.

Results: All but one of the primary study outcomes supported the harm reduction hypothesis. While controlling for typically 10 to 15 state-level differences, risks associated with opioid use diminished by 8% (RR = 0.92 [95% CI 0.91, 0.93] after legalization, 7% after medical marijuana legalization and 35% after recreational marijuana legalization (p < .05). Opioid prescriptions decreased by 8% and opioid overdose mortality diminished by 25% after medical marijuana legalization; both were even further diminished after recreational marijuana use was legalized.

Conclusion: The potential human and policy significances are clear, suggesting that such legislation profoundly affects tens of thousands to millions of physicians, patients and addicts in protective ways. All of the studies, thus far, have been state-level ecological analyses. Future individual-level analyses in Canada and the USA ought to be accomplished to replicate (or refute) this study’s estimates.

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Cannabis-Based Reductions in Opioid-Related Harms: Population-Based Observational Meta-Analysis

Abstract

Background: There is currently much debate around harms associated with easier access to cannabis. Yet, surveys of medical marijuana patients and recreational users in Canada and the USA observed that they prevalently (25% to 50%) substitute cannabis for alcohol, opioids, and other drugs, suggesting reduced harms. This synthetic study focused on arguably the most harmful substance opioids, as the growing toll of opioid-related morbidity and mortality requires harm reduction-based interventions.

Methods: Broad keyword searches of interdisciplinary research databases between 2010 and 2020 retrieved 11 studies. Their outcomes were synthesized with a sample-weighted meta-analysis that compared opioid-related outcomes before and after marijuana legalization in states that legalized marijuana versus those that had not.

Results: All but one of the primary study outcomes supported the harm reduction hypothesis. While controlling for typically 10 to 15 state-level differences, risks associated with opioid use diminished by 8% (RR = 0.92 [95% CI 0.91, 0.93] after legalization, 7% after medical marijuana legalization and 35% after recreational marijuana legalization (p < .05). Opioid prescriptions decreased by 8% and opioid overdose mortality diminished by 25% after medical marijuana legalization; both were even further diminished after recreational marijuana use was legalized.

Conclusion: The potential human and policy significances are clear, suggesting that such legislation profoundly affects tens of thousands to millions of physicians, patients and addicts in protective ways. All of the studies, thus far, have been state-level ecological analyses. Future individual-level analyses in Canada and the USA ought to be accomplished to replicate (or refute) this study’s estimates.