High‐intensity cannabis use is associated with retention in opioid agonist treatment: a longitudinal analysis

Abstract

Background and Aims: Cannabis use is common among people on opioid agonist treatment (OAT), causing concern for some care providers. However, there is limited and conflicting evidence on the impact of cannabis use on OAT outcomes. Given the critical role of retention in OAT in reducing opioid-related morbidity and mortality, we aimed to estimate the association of at least daily cannabis use on the likelihood of retention in treatment among people initiating OAT. As a secondary aim we tested the impacts of less frequent cannabis use. Design: Data were drawn from two community-recruited prospective cohorts of people who use illicit drugs (PWUD). Participants were followed for a median of 81 months (interquartile range: 37–130). Setting: Vancouver, Canada. Participants: 820 PWUD (58% men, 59% of Caucasian ethnicity, 32% HIV-positive) initiating OAT between December 1996 and May 2016. The proportion of women was higher among HIV-negative participants, with no other significant differences. Measurements: The primary outcome was retention in OAT, defined as remaining in OAT (methadone or buprenorphine/naloxone-based) for two consecutive six-month follow-up periods. The primary explanatory variable was cannabis use (at least daily versus less than daily) during the same six-month period. Confounders assessed included: socio-demographic characteristics, substance use patterns and social-structural exposures. Findings: In adjusted analysis, at least daily cannabis use was positively associated with retention in OAT (Adjusted Odds Ratio = 1.21, 95% Confidence Interval: 1.04–1.41). Our secondary analysis showed that compared with non-cannabis users, at least daily users had increased odds of retention in OAT (AOR = 1.20, 95% CI: 1.02 – 1.43), but not less than daily users (AOR = 1.00, 95% CI: 0.87 – 1.14). Conclusions: Among people who use illicit drugs initiating opioid agonist treatment in Vancouver, at least daily cannabis use was associated with approximately 21% greater odds of retention in treatment compared with less than daily consumption.

Six-month retention and changes in quality of life and substance use from a low-threshold methadone maintenance therapy programme in Durban, South Africa

“…The review notes that there is no need to address cannabis use during methadone maintenance therapy unless the service user requests assistance [67]. A recent longitudinal study confirmed that daily cannabis use was related to better treatment outcomes [68]. Cannabis is a significantly less harmful substance than heroin [2,69], is cheaper and because of a recent South African Constitutional Court ruling, the use of cannabis in a private space is now legal [70].…”

Evidence shows that cannabis has fewer relative harms than opioids

“…9,10 Recent experimental trials in humans have shown that lower doses of opioids co-administered with cannabinoids achieved analgesia equivalent to higher doses of opioids, 11 and administration of cannabidiol reduced cue-induced opioid craving among people with opioid use disorder. 12 In our 3 prospective cohorts of people at high risk of opioid overdose in Vancouver, we have found a number of beneficial long itudinal associations with consistent cannabis use, such as superior engagement in opioid agonist therapies for opioid use disorder, 13 reduced frequency of illicit opioid use in the context of chronic pain 14 and lower rates of exposure to fentanyl. 15 We strongly agree with the authors' views that governments, regulators and other stakeholders must support highquality independent research into cannabis in order to mitigate its harms and maximize its potential benefits.…”

Cannabis Use Among Patients Attending A Methadone Maintenance Treatment Clinic In Nairobi, Kenya

“…MMT is associated with attrition from the program ( 12). However, one study in Canada reported that those reporting cannabis use were more likely to be retained in opioid maintenance at six months (23). This discrepancy in findings can be explained by differences in the two studies.…”

“…This is higher than patterns recorded at baseline among patients getting enrolled in MMT in other regions. Studies in Canada have shown lower baseline prevalence of cannabis use at approximately 50% (15,23). This may reflect the difference in pattern of substance use in the different regions.…”