Modelling the impact of incarceration and prison-based hepatitis C virus (HCV) treatment on HCV transmission among people who inject drugs in Scotland

Jack Stone*, Natasha K. Martin, Matthew Hickman, Sharon J. Hutchinson, Esther Aspinall, Avril Taylor, Alison Munro, Karen Dunleavy, Erica Peters, Peter Bramley, Peter C. Hayes, David J. Goldberg, Peter Vickerman

*Corresponding author for this work

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Abstract

Background and Aims: 
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.Design: Dynamic mathematical modelling of incarceration and HCV transmission, using approximate Bayesian computation for model calibration. 
Setting: Scotland,  UK.
Participants: A simulated population of PWID
Measurements: 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. 
Findings: 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.
Original languageEnglish
Pages (from-to)1302-1314
Number of pages13
JournalAddiction
Volume112
Issue number7
Early online date3 Mar 2017
DOIs
Publication statusPublished - Jul 2017

Keywords

  • HCV transmission
  • Injecting drug use
  • incarceration

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