title: The effect of prescription opioid injection on the risk of non-fatal overdose among people who inject drugs.
abstract: OBJECTIVE
  Prescription opioid (PO) use by people who inject drugs (PWID) is a growing public health concern. Non-fatal overdose remains a leading source of morbidity among PWID, however, little is known about the relationship between PO injection and non-fatal overdose in this population. In this study we sought to examine the impact of PO injection on non-fatal overdose among PWID from Vancouver, Canada.
  
  
  METHODS
  Data were derived from two open prospective cohorts of PWID for the period of December, 2005 to May, 2014. Multivariable generalized estimating equations were used to examine the odds of overdose among those who injected: POs; heroin; and POs and heroin.
  
  
  RESULTS
  In total, 1660 PWID (33.7% women) participated in this study. In multivariable analyses, in comparison to those who were injecting non-opioid drugs, exclusive PO injection was not significantly associated with non-fatal overdose (adjusted odds ratio [AOR]: 1.17, 95% confidence interval [CI]: 0.74-1.86). The odds of non-fatal overdose were elevated for heroin injection (AOR: 1.72, 95% CI: 1.31-2.27), but were greatest for those who injected both heroin and POs (AOR: 2.46, 95% CI: 1.83-3.30).
  
  
  CONCLUSIONS
  Compared to injecting non-opioids, injecting POs exclusively did not increase risk of non-fatal overdose; however, injecting both POs and heroin doubled the risk. This may reflect consistencies in drug potency and composition when POs are used, as well as unique characteristics of exclusive PO injectors. Our findings call for the continued scale-up of evidence-based overdose prevention interventions for people who inject opioids, including POs.
authors.affiliation: British Columbia Centre for Excellence in HIV/AIDS, St. Paul's Hospital, 608-1081 Burrard Street, Vancouver, BC V6Z 1Y6, Canada; School of Population and Public Health, University of British Columbia, 2206 East Mall, Vancouver, BC V6T 1Z3, Canada.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Lake
authors.affiliation: British Columbia Centre for Excellence in HIV/AIDS, St. Paul's Hospital, 608-1081 Burrard Street, Vancouver, BC V6Z 1Y6, Canada; Department of Medicine, University of British Columbia, St. Paul's Hospital, 608-1081 Burrard Street, Vancouver, BC V6Z 1Y6, Canada.
authors.forename: Kanna
authors.initials: K
authors.lastname: Hayashi
authors.affiliation: School of Population and Public Health, University of British Columbia, 2206 East Mall, Vancouver, BC V6T 1Z3, Canada.
authors.forename: Jane
authors.initials: J
authors.lastname: Buxton
authors.affiliation: British Columbia Centre for Excellence in HIV/AIDS, St. Paul's Hospital, 608-1081 Burrard Street, Vancouver, BC V6Z 1Y6, Canada; Department of Medicine, University of British Columbia, St. Paul's Hospital, 608-1081 Burrard Street, Vancouver, BC V6Z 1Y6, Canada.
authors.forename: M-J
authors.initials: MJ
authors.lastname: Milloy
authors.affiliation: British Columbia Centre for Excellence in HIV/AIDS, St. Paul's Hospital, 608-1081 Burrard Street, Vancouver, BC V6Z 1Y6, Canada.
authors.forename: Huiru
authors.initials: H
authors.lastname: Dong
authors.affiliation: British Columbia Centre for Excellence in HIV/AIDS, St. Paul's Hospital, 608-1081 Burrard Street, Vancouver, BC V6Z 1Y6, Canada; Department of Medicine, University of British Columbia, St. Paul's Hospital, 608-1081 Burrard Street, Vancouver, BC V6Z 1Y6, Canada.
authors.forename: Evan
authors.initials: E
authors.lastname: Wood
authors.affiliation: British Columbia Centre for Excellence in HIV/AIDS, St. Paul's Hospital, 608-1081 Burrard Street, Vancouver, BC V6Z 1Y6, Canada; Department of Medicine, University of British Columbia, St. Paul's Hospital, 608-1081 Burrard Street, Vancouver, BC V6Z 1Y6, Canada.
authors.forename: Julio
authors.initials: J
authors.lastname: Montaner
authors.affiliation: British Columbia Centre for Excellence in HIV/AIDS, St. Paul's Hospital, 608-1081 Burrard Street, Vancouver, BC V6Z 1Y6, Canada; Department of Medicine, University of British Columbia, St. Paul's Hospital, 608-1081 Burrard Street, Vancouver, BC V6Z 1Y6, Canada. Electronic address: uhri-tk@cfenet.ubc.ca.
authors.forename: Thomas
authors.initials: T
authors.lastname: Kerr
mesh_terms: D000328:Adult; D001955:British Columbia; D015331:Cohort Studies; D015897:Comorbidity; D003430:Cross-Sectional Studies; D062787:Drug Overdose / Q000453:epidemiology*; D005260:Female; D006306:Health Surveys; D006556:Heroin Dependence / Q000453:epidemiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D063487:Prescription Drug Misuse / Q000706:statistics & numerical data*; D011446:Prospective Studies; D015819:Substance Abuse, Intravenous / Q000453:epidemiology*
keywords: Illicit drug use; Injection drug use; Non-fatal overdose; Opioid overdose; Prescription opioids