Medical cannabis patients reduced opioid use by 78% over six months | Research

The takeaway

In a prospective study of 1,145 Canadian medical cannabis patients, daily opioid use dropped from 152 mg to 32.2 mg morphine equivalent over six months, a 78% reduction.

Pain patients, harm reduction advocates, clinicians considering cannabis for opioid-dependent patients, and opioid crisis researchers.

78% reduction in daily opioid dosage over 6 months

What the researchers found

Among participants who used opioids at baseline (28%), the proportion dropped to 11% at six months. Mean daily opioid dosage fell from 152 mg to 32.2 mg morphine milligram equivalent, a 78% reduction. Similar reductions occurred across four other prescription drug classes, and all four quality-of-life domains improved significantly.

Why it matters

This is one of the larger prospective studies to track individual-level changes in opioid use after starting medical cannabis. The magnitude of opioid reduction and breadth of prescription drug substitution reported here are clinically significant.

The numbers in context

1,145 patients across 21 clinics; 57.6% female; median age 52; baseline opioid use 28% dropping to 11% at 6 months; 152 mg to 32.2 mg MME (78% reduction); significant improvements in all 4 WHOQOL-BREF domains

How the study worked

The Tilray Observational Patient Study enrolled patients from 21 medical clinics across Canada, following 1,145 patients with at least one post-baseline visit at 1, 3, and 6 months. Assessments included cannabis use inventory, WHOQOL-BREF quality of life measure, and detailed prescription drug questionnaire.

What this study cannot tell us

No control group. Industry-sponsored (Tilray). Self-selected patient population. Patients who dropped out may have had different outcomes. Self-reported prescription drug data.

How to read the evidence

Large multi-site prospective cohort with standardized follow-up, though lack of control group and industry sponsorship are notable limitations.

When this study was published

Published in 2021.

The bigger picture

Amid ongoing opioid crisis deaths, prospective data showing this magnitude of opioid dose reduction in real-world medical cannabis patients strengthens the case for cannabis as a harm reduction tool, though the absence of a control group limits causal conclusions.

Questions still open

How much of the opioid reduction is due to cannabis specifically versus the clinical attention and follow-up? Do these reductions persist beyond six months? What happens to patients who discontinue both cannabis and opioids?

Common questions

How much did opioid use decrease?

Daily opioid use dropped from an average of 152 mg to 32.2 mg morphine equivalent over six months, a 78% reduction. The proportion of patients using any opioids fell from 28% to 11%.

Did quality of life improve?

Yes. Statistically significant improvements were reported in all four domains of the WHOQOL-BREF quality of life measure at six months.

Read the original research

Cannabis Significantly Reduces the Use of Prescription Opioids and Improves Quality of Life in Authorized Patients: Results of a Large Prospective Study.

Pain medicine (Malden, Mass.), 22(3), 727-739

View on PubMed ↗Publisher’s paper ↗

Citation

Lucas, Philippe; Boyd, Susan; Milloy, M-J; Walsh, Zach. (2021). Cannabis Significantly Reduces the Use of Prescription Opioids and Improves Quality of Life in Authorized Patients: Results of a Large Prospective Study.. Pain medicine (Malden, Mass.), 22(3), 727-739. https://doi.org/10.1093/pm/pnaa396