title: Impact of Chronic Pain on Treatment Prognosis for Patients with Opioid Use Disorder: A Systematic Review and Meta-analysis.
abstract: BACKGROUND
  While a number of pharmacological interventions exist for the treatment of opioid use disorder, evidence evaluating the effect of pain on substance use behavior, attrition rate, and physical or mental health among these therapies has not been well established. We aim to evaluate these effects using evidence gathered from a systematic review of studies evaluating chronic non-cancer pain (CNCP) in patients with opioid use disorder.
  
  
  METHODS
  We searched the Medline, EMBASE, PubMed, PsycINFO, Web of Science, Cochrane Database of Systematic Reviews, ProQuest Dissertations and theses Database, Cochrane Central Register of Controlled Trials, World Health Organization International Clinical Trials Registry Platform Search Portal, and National Institutes for Health Clinical Trials Registry databases to identify articles evaluating the impact of pain on addiction treatment outcomes for patients maintained on opioid agonist therapy.
  
  
  RESULTS
  Upon screening 3,540 articles, 14 studies with a combined sample of 3,128 patients fulfilled the review inclusion criteria. Results from the meta-analysis suggest that pain has no effect on illicit opioid consumption [pooled odds ratio (pOR): 0.70, 95%CI 0.41-1.17; I (2) = 0.0] but a protective effect for reducing illicit non-opioid substance use (pOR: 0.57, 95%CI 0.41-0.79; I (2) = 0.0). Studies evaluating illicit opioid consumption using other measures demonstrate pain to increase the risk for opioid abuse. Pain is significantly associated with the presence of psychiatric disorders (pOR: 2.18; 95%CI 1.6, 2.9; I (2) = 0.0%).
  
  
  CONCLUSIONS
  CNCP may increase risk for continued opioid abuse and poor psychiatric functioning. Qualitative synthesis of the findings suggests that major methodological differences in the design and measurement of pain and treatment response outcomes are likely impacting the effect estimates.
authors.affiliation: Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON, Canada. ; Population Genomics Program, Chanchlani Research Centre, McMaster University, Hamilton, ON, Canada.
authors.forename: Brittany B
authors.initials: BB
authors.lastname: Dennis
authors.affiliation: Population Genomics Program, Chanchlani Research Centre, McMaster University, Hamilton, ON, Canada. ; McMaster Integrative Neuroscience Discovery and Study (MiNDS) Program, McMaster University, Hamilton, ON, Canada.
authors.forename: Monica
authors.initials: M
authors.lastname: Bawor
authors.affiliation: Michael G. Degroote School of Medicine, McMaster University, Hamilton, ON, Canada.
authors.forename: Leen
authors.initials: L
authors.lastname: Naji
authors.affiliation: School of Medicine and Medical Science, University College Dublin, Dublin, Ireland.
authors.forename: Carol K
authors.initials: CK
authors.lastname: Chan
authors.affiliation: Department of Biological Sciences, Western University, London, ON, Canada.
authors.forename: Jaymie
authors.initials: J
authors.lastname: Varenbut
authors.affiliation: Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON, Canada. ; Department of Anesthesia, McMaster University, Hamilton, ON, Canada.
authors.forename: James
authors.initials: J
authors.lastname: Paul
authors.affiliation: Canadian Addiction Treatment Centres, Richmond Hill, ON, Canada.
authors.forename: Michael
authors.initials: M
authors.lastname: Varenbut
authors.affiliation: Canadian Addiction Treatment Centres, Richmond Hill, ON, Canada.
authors.forename: Jeff
authors.initials: J
authors.lastname: Daiter
authors.affiliation: Canadian Addiction Treatment Centres, Richmond Hill, ON, Canada.
authors.forename: Carolyn
authors.initials: C
authors.lastname: Plater
authors.affiliation: 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, Richmond Hill, ON, Canada. ; Northern Ontario School of Medicine, Sudbury, ON, Canada.
authors.forename: David C
authors.initials: DC
authors.lastname: Marsh
authors.affiliation: Canadian Addiction Treatment Centres, Richmond Hill, ON, Canada. ; Department of Medicine, Hamilton General Hospital, Hamilton, ON, Canada.
authors.forename: Andrew
authors.initials: A
authors.lastname: Worster
authors.affiliation: Population Genomics Program, Chanchlani Research Centre, McMaster University, Hamilton, ON, Canada. ; Population Health Research Institute, Hamilton Health Sciences, Hamilton, ON, Canada.
authors.forename: Dipika
authors.initials: D
authors.lastname: Desai
authors.affiliation: Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON, Canada. ; Population Health Research Institute, Hamilton Health Sciences, Hamilton, ON, Canada. ; Departments of Pediatrics and Anesthesia, McMaster University, Hamilton, ON Canada. ; Centre for Evaluation of Medicine, St Joseph's Healthcare, Hamilton, ON, Canada. ; Biostatistics Unit, Father Sean O'Sullivan Research Centre, St Joseph's Healthcare, Hamilton, ON, Canada.
authors.forename: Lehana
authors.initials: L
authors.lastname: Thabane
authors.affiliation: Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON, Canada. ; Department of Psychiatry and Behavioral Neurosciences, McMaster University, Hamilton, ON, Canada. ; Peter Boris Centre for Addictions Research, Hamilton, ON, Canada.
authors.forename: Zainab
authors.initials: Z
authors.lastname: Samaan
keywords: chronic pain; guidelines; meta-analysis; opioid substitution therapy; opioid use disorder; systematic review