Does cannabis use affect opioid addiction treatment outcomes? | Research

The takeaway

A large Canadian study of 2,315 patients in opioid use disorder treatment found that overall cannabis use was not associated with opioid use during treatment, but among cannabis users, daily use and later age of onset were linked to lower odds of continued opioid use.

Addiction treatment clinicians, OUD patients who use cannabis, and policymakers weighing cannabis use in the context of opioid addiction treatment.

Daily cannabis: 39% lower odds of opioid use

What the researchers found

Any cannabis use vs non-use was not associated with opioid use during treatment (OR 1.03, 95% CI 0.87-1.23). However, among cannabis users, daily use was associated with lower odds of opioid use compared to occasional use (OR 0.61, 95% CI 0.47-0.79, p<0.001). Later age of cannabis onset and reporting cannabis-related side effects also predicted less opioid use. 51% of patients used cannabis; 70% of users were daily users.

Why it matters

With over half of OUD patients using cannabis, understanding its impact on treatment is crucial. The finding that overall cannabis use neither helps nor hinders, but that specific use patterns matter, suggests a more nuanced clinical approach than blanket policies for or against cannabis use in OUD treatment.

The numbers in context

2,315 patients; 51% (n=1,178) used cannabis; 70% of users were daily; overall cannabis use and opioid use OR=1.03 (not significant); daily vs occasional use OR=0.61 (p<0.001); 75% perceived no impact of cannabis on treatment; 50% reported side effects

How the study worked

Prospective cohort study of 2,315 patients receiving pharmacological OUD treatment from community addiction clinics in Ontario, Canada. Three-month follow-up with routine urine drug screens for opioid use. Logistic regression adjusted for confounders. Qualitative analysis of patient perceptions.

What this study cannot tell us

Observational design; daily cannabis users may differ systematically from occasional users. Self-reported cannabis use. Urine drug screens detect opioid use but not quantity. Ontario-specific population.

How to read the evidence

Large prospective study with objective opioid outcome measures (urine screens), but observational design and potential confounding.

When this study was published

Published in 2021; the intersection of cannabis policy and opioid treatment continues to evolve.

The bigger picture

The divergent findings (overall use neutral, but daily use beneficial) challenge both pro- and anti-cannabis positions in addiction treatment. Rather than a simple yes/no question, the relationship between cannabis and OUD outcomes depends on specific patterns of use.

Questions still open

Why is daily cannabis use associated with less opioid use while occasional use is not? Could daily cannabis represent intentional substitution while occasional use represents additional substance use? Should treatment programs consider cannabis frequency when developing patient plans?

Common questions

Should people in opioid treatment use cannabis?

This study found overall cannabis use neither helped nor hurt treatment outcomes. However, among those who did use cannabis, daily use was associated with less opioid use. The observational design means these findings cannot confirm cannabis caused the better outcomes.

What side effects did cannabis users report?

Half of cannabis users reported side effects, with slower thought processes (26.2%) and lack of motivation (17.3%) being most common. Interestingly, reporting side effects was associated with lower opioid use, possibly reflecting higher awareness of substance effects.

Read the original research

The association between cannabis use and outcome in pharmacological treatment for opioid use disorder.

Harm reduction journal, 18(1), 24

View on PubMed ↗Publisher’s paper ↗

Citation

Rosic, Tea; Kapoor, Raveena; Panesar, Balpreet; Naji, Leen; Chai, Darren B; Sanger, Nitika; Marsh, David C; Worster, Andrew; Thabane, Lehana; Samaan, Zainab. (2021). The association between cannabis use and outcome in pharmacological treatment for opioid use disorder.. Harm reduction journal, 18(1), 24. https://doi.org/10.1186/s12954-021-00468-6