title: Patterns of, and Factors Associated With, Illicit Pharmaceutical Opioid Analgesic Use in a Prospective Cohort of People Who Inject Drugs in Melbourne, Australia.
abstract: BACKGROUND
  People who inject drugs (PWID) are a key population engaging in pharmaceutical opioid analgesic (PO) use, yet little is known about patterns of illicit PO use among this group.
  
  
  OBJECTIVE
  The aims of this research were to measure the prevalence and frequency of lifetime and past-month illicit PO use and injection in a sample of regular PWID, to examine patterns of past-month illicit PO use within individuals over time, and to identify factors independently associated with past-month illicit PO use.
  
  
  METHODS
  Data were drawn from a prospective cohort study of regular PWID (N = 666) in Melbourne, Australia. Data from five waves of annual data collection (including baseline) were analyzed descriptively and using generalized estimating equations (GEE).
  
  
  RESULTS
  At baseline, 59% of participants reported lifetime illicit PO use and 20% reported past-month use, predominantly through injecting. Most illicit PO users at baseline transitioned to nonuse of illicit POs across the study period. In multivariable GEE analysis, factors associated with past-month illicit PO use included past-year arrest [adjusted odds ratio (AOR): 1.39], opioids other than heroin as drug of choice (AOR: 5.14), experiencing poorer physical health (AOR: 0.98) and a range of other drug use variables.
  
  
  CONCLUSIONS
  We found little evidence of ongoing illicit PO use among those followed up, with illicit PO use linked to polydrug use more broadly. Nonetheless, trends in illicit PO use among PWID should continue to be monitored and harm reduction interventions implemented to reduce the associated public health risks.
authors.affiliation: a Centre for Population Health, Burnet Institute , Melbourne , Victoria , Australia.|b School of Public Health and Preventive Medicine , Monash University , Melbourne , Victoria , Australia.
authors.forename: Danielle
authors.initials: D
authors.lastname: Horyniak
authors.affiliation: a Centre for Population Health, Burnet Institute , Melbourne , Victoria , Australia.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Agius
authors.affiliation: c National Drug and Alcohol Research Centre , University of New South Wales , Sydney , New South Wales , Australia.|d School of Population and Global Health , University of Melbourne , Melbourne , Victoria , Australia.
authors.forename: Louisa
authors.initials: L
authors.lastname: Degenhardt
authors.affiliation: a Centre for Population Health, Burnet Institute , Melbourne , Victoria , Australia.
authors.forename: Siobhan
authors.initials: S
authors.lastname: Reddel
authors.affiliation: a Centre for Population Health, Burnet Institute , Melbourne , Victoria , Australia.|b School of Public Health and Preventive Medicine , Monash University , Melbourne , Victoria , Australia.|e National Drug Research Institute , Curtin University , Melbourne , Victoria , Australia.
authors.forename: Peter
authors.initials: P
authors.lastname: Higgs
authors.affiliation: a Centre for Population Health, Burnet Institute , Melbourne , Victoria , Australia.|b School of Public Health and Preventive Medicine , Monash University , Melbourne , Victoria , Australia.
authors.forename: Campbell
authors.initials: C
authors.lastname: Aitken
authors.affiliation: a Centre for Population Health, Burnet Institute , Melbourne , Victoria , Australia.|b School of Public Health and Preventive Medicine , Monash University , Melbourne , Victoria , Australia.
authors.forename: Mark
authors.initials: M
authors.lastname: Stoové
authors.affiliation: a Centre for Population Health, Burnet Institute , Melbourne , Victoria , Australia.|b School of Public Health and Preventive Medicine , Monash University , Melbourne , Victoria , Australia.
authors.forename: Paul
authors.initials: P
authors.lastname: Dietze
mesh_terms: D000328:Adult; D019969:Amphetamine-Related Disorders / Q000453:epidemiology; D000701:Analgesics, Opioid; D001315:Australia / Q000453:epidemiology; D015331:Cohort Studies; D005260:Female; D006556:Heroin Dependence / Q000453:epidemiology; D006801:Humans; D035846:Law Enforcement; D008137:Longitudinal Studies; D008297:Male; D015999:Multivariate Analysis; D016017:Odds Ratio; D009293:Opioid-Related Disorders / Q000453:epidemiology*; D055553:Prescription Drugs; D011446:Prospective Studies; D012044:Regression Analysis; D015819:Substance Abuse, Intravenous / Q000453:epidemiology*; D055815:Young Adult
chemical_list: D000701:Analgesics, Opioid; D055553:Prescription Drugs
keywords: cohort studies; injecting drug use; pharmaceutical opioids