Association between cannabis use and methadone maintenance treatment outcomes: an investigation into sex differences

Abstract

BackgroundCannabis will soon become legalized in Canada, and it is currently unclear how this will impact public health. Methadone maintenance treatment (MMT) is the most common pharmacological treatment for opioid use disorder (OUD), and despite its documented effectiveness, a large number of patients respond poorly and experience relapse to illicit opioids. Some studies implicate cannabis use as a risk factor for poor MMT response. Although it is well established that substance-use behaviors differ by sex, few of these studies have considered sex as a potential moderator. The current study aims to investigate sex differences in the association between cannabis use and illicit opioid use in a cohort of MMT patients.MethodsThis multicentre study recruited participants on MMT for OUD from Canadian Addiction Treatment Centre sites in Ontario, Canada. Sex differences in the association between any cannabis use and illicit opioid use were investigated using multivariable logistic regression. A secondary analysis was conducted to investigate the association with heaviness of cannabis use.ResultsThe study included 414 men and 363 women with OUD receiving MMT. Cannabis use was significantly associated with illicit opioid use in women only (OR = 1.82, 95% CI 1.18, 2.82, p = 0.007). Heaviness of cannabis use was not associated with illicit opioid use in men or women.ConclusionsThis is the largest study to date examining the association between cannabis use and illicit opioid use. Cannabis use may be a sex-specific predictor of poor response to MMT, such that women are more likely to use illicit opioids if they also use cannabis during treatment. Women may show improved treatment outcomes if cannabis use is addressed during MMT.

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

“…During follow up, prevalence of cannabis use during MMT therapy continued to be high though lower than the prevalence during intake. This prevalence is consistent with similar studies done in the rest of the world which have reported a rate of 46.9-61.5% (16,21,22). This is a significant finding since continued use of cannabis during MMT has been associated with negative effects such as high attrition and increased use of illicit substances.…”

“…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).…”

“…This can be explained by the observation that women start using substances later than men but develop drug use disorders faster which may result in high attrition from MMT programs (1,32). Earlier reports have shown cannabis use by females on MMT to be a predictor for continued illicit drug use, increased risk to develop cannabis use disorder and worse mental health outcomes (16) and impact negatively on retention in treatment (15). This can be attributed to the gender differences that have been reported among people with cannabis use disorder (33,34).…”

“…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) . Some studies have shown gender differnces in these effects (16,20,21).…”

“…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) . Some studies have shown gender differnces in these effects (16,20,21). There are studies that have reported benefits of cannabis use during MMT such less money spent on acquiring heroin as a proxy measure of opioid use and reduction in opioid withdrawal symptoms (22) and retention in treatment (23) with some report on role of cannabis in opioid use disorder treatment (24).…”