title: Association between cannabis use and treatment outcomes in patients receiving methadone maintenance treatment: a systematic review protocol.
abstract: With the non-medical use of prescription opioids increasingly becoming a method of abuse in Canada, the number of patients requiring methadone maintenance treatment (MMT) for opioid use disorder has increased dramatically. The rate of cannabis use in this population is disproportionately high (~50 %). Because its use is generally perceived as harmless, cannabis use is often not monitored during MMT. Current literature regarding the effects of cannabis use on MMT is conflicting, and the presence and nature of an association has not been clearly established. The primary objective of this review will be to conduct a systematic review of the literature and, if appropriate, a meta-analysis to determine whether there is an association between cannabis use and MMT outcomes. A secondary objective will be to perform subgroup analyses (by age, sex, method of cannabis measurement, and country) to determine whether cannabis use differentially influences MMT outcomes within these subgroups.
  
  
  
  The search will be conducted on the following electronic databases using a predefined search strategy: MEDLINE, EMBASE, PsycINFO, and Cumulative Index to Nursing and Allied Health Literature (CINAHL). Two authors (LZ and MB) will independently screen articles using predetermined inclusion/exclusion criteria and will extract data from included articles using a pilot-tested data extraction form. Disagreements at all stages of the screening process will be settled through discussion, and when consensus cannot be reached, a third author (ZS) will be consulted. An assessment of quality and risk of bias will be conducted on all included articles, and a sensitivity analysis will be used to compare results of studies with high and low risk of bias. We will perform random- and fixed-effects meta-analyses, if appropriate, with heterogeneity calculated using the I (2) statistic and formal evaluation of publication bias.
  
  
  
  Results of this systematic review will elucidate the association between cannabis use and methadone maintenance treatment outcomes. We will provide evidence that will be useful to clinicians regarding whether monitoring cannabis use during MMT is advantageous for optimizing MMT outcomes.
  
  
  
  PROSPERO CRD42015029372.
authors.affiliation: MiNDS Neuroscience Graduate Program, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4L8, Canada.
authors.forename: Laura
authors.initials: L
authors.lastname: Zielinski
authors.affiliation: Health Research Methodology Graduate Program, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4L8, Canada.
authors.forename: Meha
authors.initials: M
authors.lastname: Bhatt
authors.affiliation: MiNDS Neuroscience Graduate Program, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4L8, Canada.
authors.forename: Rebecca B
authors.initials: RB
authors.lastname: Eisen
authors.affiliation: Health Research Methodology Graduate Program, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4L8, Canada.|Department of Clinical Epidemiology and Biostatistics, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4L8, Canada.
authors.forename: Stefan
authors.initials: S
authors.lastname: Perera
authors.affiliation: Health Science Library, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4L8, Canada.
authors.forename: Neera
authors.initials: N
authors.lastname: Bhatnagar
authors.affiliation: Department of Psychiatry and Behavioural Neurosciences, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4L8, Canada.|Peter Boris Centre for Addictions Research, St. Joseph's Healthcare Hamilton, 100 West 5th Street, Hamilton, ON, L8N 3K7, Canada.
authors.forename: James
authors.initials: J
authors.lastname: MacKillop
authors.affiliation: Department of Psychiatry and Behavioural Neurosciences, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4L8, Canada.|Women's Health Concerns Clinic, St. Joseph's Healthcare Hamilton, 100 West 5th Street, Hamilton, ON, L8N 3K7, Canada.|Department of Obstetrics and Gynecology, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4L8, Canada.
authors.forename: Meir
authors.initials: M
authors.lastname: Steiner
authors.affiliation: Department of Psychiatry and Behavioural Neurosciences, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4L8, Canada.|Cleghorn Early Intervention Clinic, St. Joseph's Healthcare Hamilton, 50 Charlton Avenue E., Hamilton, ON, L8N 4A6, Canada.
authors.forename: Stephanie
authors.initials: S
authors.lastname: McDermid Vaz
authors.affiliation: Department of Clinical Epidemiology and Biostatistics, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4L8, Canada.|Biostatistics Unit, Research Institute at St Joes, St. Joseph's Healthcare Hamilton, 50 Charlton Avenue E., Hamilton, ON, L8N 4A6, Canada.
authors.forename: Lehana
authors.initials: L
authors.lastname: Thabane
authors.affiliation: Department of Clinical Epidemiology and Biostatistics, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4L8, Canada. samaanz@mcmaster.ca.|Department of Psychiatry and Behavioural Neurosciences, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4L8, Canada. samaanz@mcmaster.ca.|Peter Boris Centre for Addictions Research, St. Joseph's Healthcare Hamilton, 100 West 5th Street, Hamilton, ON, L8N 3K7, Canada. samaanz@mcmaster.ca.|Population Genomics Program, Chanchlani Research Centre, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4L8, Canada. samaanz@mcmaster.ca.|Mood Disorders Program, St. Joseph's Healthcare Hamilton, 100 West 5th St., Hamilton, ON, L8N 3K7, Canada. samaanz@mcmaster.ca.
authors.forename: Zainab
authors.initials: Z
authors.lastname: Samaan
mesh_terms: D000701:Analgesics, Opioid; D002188:Cannabis / Q000009:adverse effects; D006801:Humans; D002189:Marijuana Abuse; D008385:Marijuana Smoking; D008691:Methadone / Q000627:therapeutic use*; D058850:Opiate Substitution Treatment; D009293:Opioid-Related Disorders / Q000628:therapy*; D012107:Research Design; D000078202:Systematic Reviews as Topic; D016896:Treatment Outcome
chemical_list: D000701:Analgesics, Opioid; D008691:Methadone
keywords: Cannabis; MMT; Marijuana; Methadone maintenance treatment; Protocol; Systematic review