title: Modelling the impact of incarceration and prison-based hepatitis C virus (HCV) treatment on HCV transmission among people who inject drugs in Scotland.
abstract: OBJECTIVE
  People who inject drugs (PWID) experience high incarceration rates, and previous incarceration is associated with elevated hepatitis C virus (HCV) transmission risk. In Scotland, national survey data indicate lower HCV incidence in prison than the community (4.3 versus 7.3 per 100 person-years), but a 2.3-fold elevated transmission risk among recently released (< 6 months) PWID. We evaluated the contribution of incarceration to HCV transmission among PWID and the impact of prison-related prevention interventions, including scaling-up direct-acting antivirals (DAAs) in prison.
  
  
  METHODS
  Dynamic mathematical modelling of incarceration and HCV transmission, using approximate Bayesian computation for model calibration.
  
  
  METHODS
  Scotland, UK.
  
  
  METHODS
  A simulated population of PWID.
  
  
  METHODS
  Population-attributable fraction (PAF) of incarceration to HCV transmission among PWID. Decrease in HCV incidence and chronic prevalence due to current levels of prison opiate substitution therapy (OST; 57% coverage) and HCV treatment, as well as scaling-up DAAs in prison and/or preventing the elevated risk associated with prison release.
  
  
  RESULTS
  Incarceration contributes 27.7% [PAF; 95% credible interval (CrI) -3.1 to 51.1%] of HCV transmission among PWID in Scotland. During the next 15 years, current HCV treatment rates (10.4/6.8 per 1000 incarcerated/community PWID annually), with existing prison OST, could reduce incidence and chronic prevalence among all PWID by a relative 10.7% (95% CrI = 8.4-13.3%) and 9.7% (95% CrI = 7.7-12.1%), respectively. Conversely, without prison OST, HCV incidence and chronic prevalence would decrease by 3.1% (95% CrI = -28.5 to 18.0%) and 4.7% (95% CrI = -11.3 to 14.5%). Additionally, preventing the heightened risk among recently released PWID could reduce incidence and chronic prevalence by 45.0% (95% CrI = 19.7-57.5%) and 33.3% (95% CrI = 15.6-43.6%) or scaling-up prison HCV treatments to 80% of chronic PWID prison entrants with sufficient sentences (>16 weeks) could reduce incidence and prevalence by 45.6% (95% CrI = 38.0-51.3%) and 45.5% (95% CrI = 39.3-51.0%), respectively.
  
  
  CONCLUSIONS
  Incarceration and the elevated transmission risk following prison release can contribute significantly to hepatitis C virus transmission among people who inject drugs. Scaling-up hepatitis C virus treatment in prison can provide important prevention benefits.
authors.affiliation: School of Social and Community Medicine, University of Bristol, Bristol, UK.
authors.forename: Jack
authors.identifier: http://orcid.org/0000-0002-4584-0068
authors.initials: J
authors.lastname: Stone
authors.affiliation: School of Social and Community Medicine, University of Bristol, Bristol, UK.|Division of Global Public Health, University of California San Diego, San Diego, CA, USA.
authors.forename: Natasha K
authors.initials: NK
authors.lastname: Martin
authors.affiliation: School of Social and Community Medicine, University of Bristol, Bristol, UK.
authors.forename: Matthew
authors.initials: M
authors.lastname: Hickman
authors.affiliation: School of Health and Life Sciences, Glasgow Caledonian University, Glasgow, UK.|Health Protection Scotland, Glasgow, UK.
authors.forename: Sharon J
authors.initials: SJ
authors.lastname: Hutchinson
authors.affiliation: School of Health and Life Sciences, Glasgow Caledonian University, Glasgow, UK.|Health Protection Scotland, Glasgow, UK.
authors.forename: Esther
authors.initials: E
authors.lastname: Aspinall
authors.affiliation: School of Media, Culture and Society, University of the West of Scotland, Paisley, UK.
authors.forename: Avril
authors.initials: A
authors.lastname: Taylor
authors.affiliation: School of Media, Culture and Society, University of the West of Scotland, Paisley, UK.
authors.forename: Alison
authors.initials: A
authors.lastname: Munro
authors.affiliation: School of Media, Culture and Society, University of the West of Scotland, Paisley, UK.
authors.forename: Karen
authors.initials: K
authors.lastname: Dunleavy
authors.affiliation: Gartnavel General Hospital, Glasgow, UK.
authors.forename: Erica
authors.initials: E
authors.lastname: Peters
authors.affiliation: NHS Forth Valley Viral Hepatitis Service, Stirling, UK.
authors.forename: Peter
authors.initials: P
authors.lastname: Bramley
authors.affiliation: Division of Health Sciences, Royal Infirmary Edinburgh, Edinburgh, UK.
authors.forename: Peter C
authors.initials: PC
authors.lastname: Hayes
authors.affiliation: School of Health and Life Sciences, Glasgow Caledonian University, Glasgow, UK.|Health Protection Scotland, Glasgow, UK.
authors.forename: David J
authors.initials: DJ
authors.lastname: Goldberg
authors.affiliation: School of Social and Community Medicine, University of Bristol, Bristol, UK.
authors.forename: Peter
authors.initials: P
authors.lastname: Vickerman
mesh_terms: D000998:Antiviral Agents / Q000627:therapeutic use*; D001499:Bayes Theorem; D015897:Comorbidity; D006526:Hepatitis C / Q000188:drug therapy* / Q000453:epidemiology*; D006801:Humans; D015994:Incidence; D008962:Models, Theoretical; D011329:Prisoners / Q000706:statistics & numerical data*; D011330:Prisons; D012606:Scotland; D015819:Substance Abuse, Intravenous / Q000453:epidemiology*
chemical_list: D000998:Antiviral Agents
keywords: DAAs; HCV; OST; mathematical model; people who inject drugs; prison