Modeling the role of incarceration in HCV transmission and prevention amongst people who inject drugs in rural Kentucky.

BACKGROUND

People who inject drugs (PWID) experience high incarceration rates, with current/recent incarceration being associated with increased hepatitis C virus (HCV) transmission. We assess the contribution of incarceration to HCV transmission amongst PWID in Perry County (PC), Kentucky, USA, and the impact of scaling-up community and in-prison opioid substitution therapy (OST), including the potential for reducing incarceration.

METHODS

A dynamic model of incarceration and HCV transmission amongst PWID was calibrated in a Bayesian framework to epidemiological and incarceration data from PC, incorporating an empirically estimated 2.8-fold (95%CI: 1.36-5.77) elevated HCV acquisition risk amongst currently incarcerated or recently released (<6 months) PWID compared to other PWID. We projected the percentage of new HCV infections that would be prevented among PWID over 2020-2030 if incarceration no longer elevated HCV transmission risk, if needle and syringe programmes (NSP) and OST are scaled-up, and/or if drug use was decriminalized (incarceration/reincarceration rates are halved) with 50% of PWID that would have been imprisoned being diverted onto OST. We assume OST reduces reincarceration by 10-42%.

RESULTS

Over 2020-2030, removing the effect of incarceration on HCV transmission could prevent 42.7% (95% credibility interval: 15.0-67.4%) of new HCV infections amongst PWID. Conversely, scaling-up community OST and NSP to 50% coverage could prevent 28.5% (20.0-37.4%) of new infections, with this increasing to 32.7% (24.5-41.2%) if PWID are retained on OST upon incarceration, 36.4% (27.7-44.9%) if PWID initiate OST in prison, and 45.3% (35.9-54.1%) if PWID are retained on OST upon release. decriminalization (with diversion to OST) could further increase this impact, preventing 56.8% (45.3-64.5%) of new infections. The impact of these OST interventions decreases by 2.1-28.6% if OST does not reduce incarceration.

CONCLUSION

Incarceration is likely to be an important contributor to HCV transmission amongst PWID in PC. Prison-based OST could be an important intervention for reducing this risk.