Table 2.
Full Model Parameters obtained from literature and data analyses.
| Parameter | Symbol | Range of Parameter Values | Source and Comments |
|---|---|---|---|
| Inflow of new injectors per year | θ | - | Fit to PWID population size |
| HCV incidence among PWID per 100 person years (2008 unless stated otherwise) | Vary infection rate, λ, to fit. | Estimated from NESI data(23) and prison survey(9). See section 3.2 of the supplementary details. HCV incidences are sampled from the distributions obtained by a bootstrapping method to estimate the 95% confidence intervals. | |
| Recent community PWID (<5 years injecting) | 11.9–40.6 | ||
| Non-recent community PWID (>5yrs injecting) | 4.8–19.5 | ||
| Incarcerated PWID with OST (2010/11) | 0.9–10.2 | Incidence amongst incarcerated PWID in absence of OST is sampled from lognormal(2.3,0.6) which is truncated to the 95% confidence interval (4.5,31.8) found in previous prison survey before OST was introduced(14). | |
| Incarcerated PWID without OST | 4.5–31.8 | ||
| HCV antibody prevalence | |||
| Community PWID (2008) | 49.7–54.0% | (23) | |
| Incarcerated PWID (2010/11) | 51.0–55.9% | (9) | |
| Proportion of new infections that spontaneously clear | α | 0.22–0.29 | (30) Sampled from uniform distribution |
| Annual PWID treatments in community (Average rate per 1000 Community PWID) | Φc | (27, 28) | |
| 2008–2014 | 66–103 (4.4–6.8) | ||
| 2015–2030 | 103 (6.8) | ||
| Annual PWID treatments in Prison (Average rate per 1000 Incarcerated PWID) | Φp | (27, 28) | |
| 2008–2014 | 4–16 (2.6–10.4) | ||
| 2015–2030 | Varied | ||
| Sustained viral response | π | ||
| PEG-IFN/RBV in community | 60–66% | (29) Sampled from uniform distribution | |
| PEG-IFN/RBV in prison | 55–66% | (29) Sampled from uniform distribution | |
| DAAs (2015–2030) | 90% | (16) | |
| Percentage of incarcerated PWID with sentences: | |||
| >16 weeks | ε | 39.9–46.0% | Estimated from the prison survey. Both sampled from normal distribution |
| >12 weeks | ε2 | 57.3–63.3% | |
| Increased risk amongst recently released PWID (<6 months since release) | η | 0.97–5.46 | Estimated from NESI data (see section 3.1 of the supplementary details). Sampled from lognormal distribution |