Cannabis use during methadone maintenance treatment for opioid use disorder: a systematic review and meta-analysis

Abstract

T he opioid epidemic related to an increase in prescriptions [1][2][3][4] has escalated in the past 2 decades. Opioid use disorder is a fundamental component of this crisis. 5,6 Despite the morbidity and mortality due to opioid use disorder, high rates of HIV infection and hepatitis C among patients with the disorder and high unemployment rates, treatment options are limited in scope and effectiveness. 7,8 Methadone maintenance therapy is the most common treatment for opioid use disorder, 9,10 although other treatments are available. 11 Despite the reported benefits of methadone maintenance therapy in managing opioid use disorder, the number of patients receiving this therapy who continue to use illicit opioids is high. 12 The rates of cannabis use among patients receiving methadone maintenance therapy are higher than those in the general population: about a third of Canadians have used cannabis once in their lifetime, 13 whereas 59.7% of males and 43.5% of females receiving methadone maintenance therapy reported having used cannabis. [14][15][16] Research suggests that polydrug use (aside from cannabis) is prevalent in the methadone maintenance therapy population. 17,18 There is limited evidence to suggest that cannabis use may reduce opioid use in pain management 19 but not in opioid use disorder. 20 Studies have shown that, in US states with dispensary-based medical cannabis laws, fewer prescription opioids are dispensed, 21 and there are fewer opioid-related deaths. 22 The US Department of Veterans Affairs has suggested that cannabis should be legalized not only as a mechanism to lower prescription opioid use but also to manage opioid withdrawal. 23 This report made headlines labelling cannabis as an "exit drug." 23 However, the "exit hypothesis" -the idea that cannabis can be used to manage withdrawal symptoms and therefore help patients with opioid use disorder to stop using opioidshas not been examined systematically. With the legalization of

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

“…Among the participants using cannabis during follow up, 38.5% used cannabis in combination with another substance, majority using cannabis together with heroin. This pattern of polysubstance is common in patients on methadone therapy (14). Additionally, majority of those using cannabis at intake, continued use during follow up and were more likely to be lost to follow up compared to cannabis non-users.…”

“…Polysubstance use is common among patients on methadone maintenance treatment globally with cannabis being the most frequently used drug in this population. In addition, prevalence of cannabis use in patients on methadone maintenance treatment is higher than the prevalence in the general population (14). Some studies have reported a high prevalence ranging at 50-70% (15,16).…”

“…while a study in Finland reported a lower prevalence of 30% (17). A systematic review of 23 studies reported prevalence of cannabis use in opioid use disorder to range 11.2%-78.6% (14). A study in Iran eported gender differenc in use where the prevalence of cannabis use in males was 25% and 5% for females (18).…”

“…Research on effect of cannabis use during MMT has reported mixed results (14). Some studies have shown negative effects such as increased risk to drop out of treatment (15), continued illicit opioid use (16), poor psychosocial functioning, increased rate of incarceration for those with cannabis dependence at baseline (15) and poor family relationships (16,19), use of other substance(20,21) physical and psychological health problems (21) .…”

<p>Children and Youth Who Use Cannabis for Pain Relief: Benefits, Risks, and Perceptions</p>

“…58 Most recently, a 2019 systematic review and meta-analysis of adults with opioid use disorder found no effect of cannabis use in opioid use. 59 Therefore, findings on this topic continue to be too mixed and scarce to allow strong conclusions.…”