title: Association between cannabis use and methadone maintenance treatment outcomes: an investigation into sex differences.
abstract: Cannabis 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.
  
  
  
  This 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.
  
  
  
  The 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.
  
  
  
  This 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.
authors.affiliation: MiNDS Neuroscience Graduate Program, McMaster University, Hamilton, ON Canada.
authors.forename: Laura
authors.initials: L
authors.lastname: Zielinski
authors.affiliation: Health Research Methodology Graduate Program, McMaster University, Hamilton, ON Canada.
authors.forename: Meha
authors.initials: M
authors.lastname: Bhatt
authors.affiliation: Medical Science Graduate Program, McMaster University, Hamilton, ON Canada.
authors.forename: Nitika
authors.initials: N
authors.lastname: Sanger
authors.affiliation: Canadian Addiction Treatment Centres, Hamilton, ON Canada.
authors.forename: Carolyn
authors.initials: C
authors.lastname: Plater
authors.affiliation: Canadian Addiction Treatment Centres, Hamilton, ON Canada.|Department of Medicine, McMaster University, Hamilton, ON Canada.
authors.forename: Andrew
authors.initials: A
authors.lastname: Worster
authors.affiliation: Canadian Addiction Treatment Centres, Hamilton, ON Canada.
authors.forename: Michael
authors.initials: M
authors.lastname: Varenbut
authors.affiliation: Canadian Addiction Treatment Centres, Hamilton, ON Canada.
authors.forename: Jeff
authors.initials: J
authors.lastname: Daiter
authors.affiliation: Population Genomics Program, Chanchlani Research Centre, McMaster University, Hamilton, ON Canada.|Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON Canada.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Pare
authors.affiliation: Canadian Addiction Treatment Centres, Hamilton, ON Canada.|Northern Ontario School of Medicine, Sudbury, ON Canada.
authors.forename: David C
authors.initials: DC
authors.lastname: Marsh
authors.affiliation: Population Genomics Program, Chanchlani Research Centre, McMaster University, Hamilton, ON Canada.
authors.forename: Dipika
authors.initials: D
authors.lastname: Desai
authors.affiliation: Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, ON Canada.|Peter Boris Centre for Addictions Research, St. Joseph's Healthcare Hamilton, Hamilton, ON Canada.
authors.forename: James
authors.initials: J
authors.lastname: MacKillop
authors.affiliation: Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, ON Canada.|Women's Health Concerns Clinic, St. Joseph's Healthcare Hamilton, Hamilton, ON Canada.|Department of Obstetrics and Gynaecology, McMaster University, Hamilton, ON Canada.
authors.forename: Meir
authors.initials: M
authors.lastname: Steiner
authors.affiliation: Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, ON Canada.|Cleghorn Early Intervention Clinic, St. Joseph's Healthcare Hamilton, Hamilton, ON Canada.
authors.forename: Stephanie
authors.initials: S
authors.lastname: McDermid Vaz
authors.affiliation: Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON Canada.|Biostatistics Unit, Research Institute at St Joes, St. Joseph's Healthcare Hamilton, Hamilton, ON Canada.
authors.forename: Lehana
authors.initials: L
authors.lastname: Thabane
authors.affiliation: Population Genomics Program, Chanchlani Research Centre, McMaster University, Hamilton, ON Canada.|Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON Canada.|Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, ON Canada.|Peter Boris Centre for Addictions Research, St. Joseph's Healthcare Hamilton, Hamilton, ON Canada.
authors.forename: Zainab
authors.initials: Z
authors.lastname: Samaan
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002188:Cannabis; D005260:Female; D006801:Humans; D008297:Male; D008385:Marijuana Smoking / Q000453:epidemiology*; D008691:Methadone / Q000627:therapeutic use*; D008875:Middle Aged; D009864:Ontario; D058850:Opiate Substitution Treatment; D009293:Opioid-Related Disorders / Q000188:drug therapy* / Q000453:epidemiology*; D012727:Sex Characteristics; D055815:Young Adult
chemical_list: D008691:Methadone
keywords: Cannabis; Methadone maintenance treatment; Opioid; Opioid use disorder; Sex differences