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Publication - Professor Matthew Hickman

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

    Citation

    Stone, J, Martin, N, Hickman, M, Hutchinson, SJ, Aspinall, E, Taylor, A, Munro, A, Dunleavy, K, Peters, E, Bramley, P, Hayes, P, Goldberg, DJ & Vickerman, P, 2017, ‘Modelling the impact of incarceration and prison-based HCV treatment on HCV transmission among people who inject drugs in Scotland’. Addiction.

    Abstract

    Background/Aims: People who inject drugs (PWID) experience high incarceration rates, and previous incarceration is associated with elevated hepatitis C virus (HCV) transmission risk. We evaluate the contribution of incarceration to HCV transmission amongst 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; where national survey data indicates lower HCV incidence in prison than the community (4.3 vs 7.3 per 100py), but a 2.3-fold elevated transmission risk amongst recently released (<6 months) PWID.

    Participants: PWID

    Measurements: Population attributable fraction of incarceration (PAF) 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%CrI -3.1-51.1%) of HCV transmission amongst PWID in Scotland. Over 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 -28.5-18.0%) and 4.7% (95%CrI -11.3-14.5%). 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 HCV transmission amongst PWID. Scaling-up HCV treatment in prison can provide important prevention benefits.

    Full details in the University publications repository