Addressing viral hepatitis C reinfections in a low-threshold programme for people who inject drugs in Slovenia.

Background: Hepatitis C virus (HCV) infection remains a public health threat. Although therapy with direct-acting antivirals made its elimination possible, major challenges remain in treating vulnerable populations, such as people who inject drugs (PWID) enrolled in low-threshold programmes (LTPs). This study analysed the outcome of HCV management focused on HCV reinfection in a specifically designed model-of-care (MoC) for PWID in Slovenia, where treatment is prescribed without limitations, though only by specialist physicians.

Methods: All HCV antibody (anti-HCV) positive users of a MoC, combining HCV management at Clinic for Infectious Diseases at the University Medical Centre in Ljubljana and LTP for PWID in 100 km distanced civil society organisation (CSO) Svit Koper, between January 2017 to December 2022, were included. The MoC enabled regular transportation of PWID between LTP and the Clinic, where specifically assigned services for individually tailored HCV management in cooperation with CSO were available. Data on participants´ demographic, epidemiological, and clinical characteristics were collected partly retrospectively and prospectively, with a particular focus on HCV treatment outcome and reinfection status, and analysed accordingly.

Results: The study included 49 anti-HCV positive PWID with a mean age of 38.7 (standard deviation (SD) = 7.6) years at first visit. The majority was male (40/49, 81.6%); 16/49 (32.7%) experienced previous incarceration, 14/49 (28.6%) were experiencing homelessness, and 42/49 (85.7%) were receiving opioid agonist therapy. A total of 42/49 (83.7%) were HCV RNA-positive. Of them 36/42 (85.7%) started HCV treatment at a mean age of 42.7 (SD = 5.7) years and 33/36 (91.7%) completed treatment. Six (14.3%) HCV RNA-positive PWID died. Among 28/33 (84.9%) who achieved a sustained virological response 12 weeks post treatment, 6/28 (21.4%) presented with reinfection. The HCV reinfection rate was 13.3 per 100 - PY (95% confidence interval (CI) [6.0, 29.7]), the rate of positive HCV RNA re-test was 12.2 per 100 - PY (95%CI [7.7-16.7]), while hazard of reinfection in our cohort increased with time, with the estimated reinfection probability exceeding 0.5 at 4 years.

Conclusions: In marginalised population of PWID attending LTP, a sustainable HCV RNA re-screening and follow-up after HCV cure are necessary, as the risk of reinfection remains high.