Model projections on the impact of HCV treatment in the prevention of HCV transmission among people who inject drugs in Europe

Abstract

Background & aims: Prevention of hepatitis C virus (HCV) transmission among people who inject drugs (PWID) is critical for eliminating HCV in Europe. We estimated the impact of current and scaled-up HCV treatment with and without scaling up opioid substitution therapy (OST) and needle and syringe programmes (NSPs) across Europe over the next 10 years.

Methods: We collected data on PWID HCV treatment rates, PWID prevalence, HCV prevalence, OST, and NSP coverage from 11 European settings. We parameterised an HCV transmission model to setting-specific data that project chronic HCV prevalence and incidence among PWID.

Results: At baseline, chronic HCV prevalence varied from <25% (Slovenia/Czech Republic) to >55% (Finland/Sweden), and <2% (Amsterdam/Hamburg/Norway/Denmark/Sweden) to 5% (Slovenia/Czech Republic) of chronically infected PWID were treated annually. The current treatment rates using new direct-acting antivirals (DAAs) may achieve observable reductions in chronic prevalence (38-63%) in 10 years in Czech Republic, Slovenia, and Amsterdam. Doubling the HCV treatment rates will reduce prevalence in other sites (12-24%; Belgium/Denmark/Hamburg/Norway/Scotland), but is unlikely to reduce prevalence in Sweden and Finland. Scaling-up OST and NSP to 80% coverage with current treatment rates using DAAs could achieve observable reductions in HCV prevalence (18-79%) in all sites. Using DAAs, Slovenia and Amsterdam are projected to reduce incidence to 2 per 100 person years or less in 10 years. Moderate to substantial increases in the current treatment rates are required to achieve the same impact elsewhere, from 1.4 to 3 times (Czech Republic and France), 5-17 times (France, Scotland, Hamburg, Norway, Denmark, Belgium, and Sweden), to 200 times (Finland). Scaling-up OST and NSP coverage to 80% in all sites reduces treatment scale-up needed by 20-80%.

Conclusions: The scale-up of HCV treatment and other interventions is needed in most settings to minimise HCV transmission among PWID in Europe.

Lay summary: Measuring the amount of HCV in the population of PWID is uncertain. To reduce HCV infection to minimal levels in Europe will require scale-up of both HCV treatment and other interventions that reduce injecting risk (especially OST and provision of sterile injecting equipment).

Keywords: Direct-acting antivirals; Hepatitis C; Opioid substitution therapy; PWID.

Figure 1. Schematics of HCV transmission (1a) and OST and NSP interventions (1b) in the model

a: Infection component of the model b: OST and NSP intervention component of the model

Figure 2. Percentage of estimated PWID with chronic HCV infections treated annually at baseline (2015/16) for each site

Bars indicate the median and interquartile range and whiskers show the 95% credibility intervals.

Figure 3. Baseline and projected 10 year chronic HCV prevalence among PWID in multiple sites in Europe for various treatment intervention scenarios

Baseline chronic prevalence (blue boxes) and projected 10 year chronic prevalence if either current treatment rates continue with new DAAs (green boxes), treatment rates are doubled with new DAAs (yellow boxes), or increased to 50 per 1000 PWID annually with new DAAs (pink boxes). Bars indicate the median and interquartile range and whiskers show the 95% credibility intervals.

Figure 4. Baseline and projected 10 year chronic HCV prevalence among PWID in multiple sites in Europe for various treatment intervention scenarios with OST and NSP scaled-up to 80% coverage

Baseline chronic prevalence (blue boxes) and projected 10-year chronic prevalence if either current treatment rates continue with new DAAs (green boxes), treatment rates are doubled with new DAAs (yellow boxes), or increased to 50 per 1000 PWID annually with new DAAs (pink boxes) with OST and NSP scaled-up to 80% coverage. Bars indicate the median and interquartile range and whiskers show the 95% credibility intervals.

Figure 5. Current and projected number of treatments per 1000 PWID to reduce incidence to 2 per 100 pyrs by 2026

Current number of treatments per 1000 PWID at baseline (2015/16, blue) and required scale-up in number of treatments per 1000 PWID initially needed per year (2016/17) if current OST and NSP coverage is maintained (green, median and 95% credibility interval shown in figure) or if OST and NSP are scaled to 80% coverage (yellow) to reduce incidence to 2 per 100 pyrs (2%) by 2026. Based on data from the sites we have: ¹Treatment initially given only to those on OST. ²Treatment initially given to all PWID. ³70% treatment to PWIDs on OST, 30% treatment to PWIDs not on OST.