Background
Methods
Mathematical model
Calibration Data | ||||
Calibrated parameter | Value and Source | |||
Number of diagnosed and in care HIV-infected and chronic HCV coinfected (HIV+/HCV+) in 2015 | 3075 as observed in the HERACLES cohort [17], with 2669 [range 2402–2936] with a history of PWID | |||
HCV chronic prevalence among PWID injecting for < 10 years in 2010 | 45% [sampled uniformly from 40 to 50%]. Values from Folch et al. [29], adjusted for weighted spontaneous clearance given HIV coinfection prevalence and spontaneous clearance rates by HIV-status in the below table. | |||
HCV chronic prevalence among PWID injecting for > 10 years in 2010 | 60% [sampled uniformly from 55 to 65%] Values taken from Folch et al. [29], adjusted for weighted spontaneous clearance given HIV coinfection prevalence and spontaneous clearance rates by HIV-status in the below table. | |||
HIV prevalence among PWID injecting for <10 years, in 2010 | 20% [sampled uniformly from 10 to 30%] Values from Folch et al. [29] | |||
HIV prevalence among PWID injecting for > 10 years in 2010 | 40% [sampled uniformly 30–50%]. Values from Folch et al. [29] | |||
HCV chronic prevalence among HIV+ ever PWID in 2015 | 54% [sampled uniformly 50–58%] [18] | |||
Proportion of HIV+/HCV+ diagnosed individuals who are current PWID in 2015 | 14% [sampled uniformly 10–18%] as observed in the HERACLES cohort [17] | |||
Proportion HIV+/HCV+ diagnosed ever PWID who had previously failed HCV treatment in 2015 | 32% [sampled uniformly 30–34%] as observed in the HERACLES cohort [17] | |||
General Parameters | ||||
Parameter Definition | Symbol | Sampled Value and 95% Interval | Sampling Distribution | Source |
Sustained HCV viral response, monoinfected on DAAs | 1- fmd | 0.9 | [2] | |
Sustained HCV viral response, coinfected on DAAs | 1- fcd | 0.948 | HERACULES cohort | |
Sustained HCV viral response, monoinfected pre-DAAs | 1- fmpd | 0.52 (0.45–0.60) | Uniform [0.45–0.60] | |
Sustained HCV viral response, coinfected pre-DAAs | 1- fcpd | 0.30 (0.20.-0.39) | Uniform [0.20–0.40] | |
Excess death rate due to mono-infection with HIV untreated per year | μuHIV | 0.097 (0.09–0.10) | Uniform [1/9.6–1/11.5] | [33] |
Decreased mortality hazard ratio for HIV on ART | μHIV | 0.26 (0.20–0.32) | Uniform [1/5–1/3] | |
Excess death rate due to chronic HCV mono-infection per year | μHCV | 0.00169 (0.0016–0.00181) | Uniform [0.00154–0.00183] | [36] |
Relative risk of death due to chronic HCV for HIV/HCV coinfection not on HIV treatment compared to HCV monoinfection | RR_co_noART | 2.58 (1.70–3.99) | Lognormal, from distribution 2.5 (95%CI 1.8–3.4) | |
Excess death rate due to HCV for HIV-HCV co-infection with no HIV treatment per year | μHCVuHIV | 0.0042 (0.0039–0.0046) | Uniform [0.0038–0.0046] | |
Relative risk of death due to chronic HCV for HIV/HCV coinfection on HIV treatment compared to HIV/HCV coinfection no HIV treatment | RR_coART | 0.68 | ||
Excess death rate due to HIV for HIV-HCV co-infection with no HIV treatment per year | μuHIVHCV | 0.0005 (0.00041–0.00066) | Uniform [0.0004–0.00069] | [36] |
PWID parameters | ||||
Inflow of new PWID per year | θ | Deaths replaced, rate is halved in 2011. See text for discussion. | ||
Population size of active PWID in 2010 | 7,500 (5,000-10,000) | Uniform [5,000-10,000] | ||
HCV treatment rate among PWID who are HIV- or HIV+ and undiagnosed (%/year) | r, rhu | 0.99% (0.54–1.44%) | Uniform [0.5–1.5%] | Assumed similar to estimates worldwide [40] |
HCV treatment rate among HIV+ diagnosed individuals prior to 2015 (%/year) | rhd | Calibrated | Calibrated to fit HERACLES data on proportion previously failed treatment in 2015 | |
HCV treatment rate among HIV+ diagnosed individuals from 2015 to 2020 (%/year) | rhd | 33% | HERACLES cohort (unpublished data from 2015 to 2017) | |
Average duration of injecting until final cessation (years) | 1/μcd | 15.1 (6.8–24.4) | Uniform [5–25] | |
Background mortality rate per year among PWID | μ | 0.0179 | Average life expectancy in Spain to 80.7 (WHO life table), and average age of injecting initiation age of 25 [43] | |
Overdose mortality rate among PWID per year | μIDU | 0.0062 (0.005–0.007) | Uniform [0.0053–0.0070] | [44] |
Relative risk of HIV transmission through sex for those on ART | RRHIVs | 0.107 (0.03–0.198) | Lognormal [95% CI 0.01–0.27] | [45] |
Relative risk of HIV transmission through injecting for those on ART | RRHIVi | 0.50 (0.27–0.72) | Uniform [0.25–0.75] | Limited data. One modeling study in Vancouver estimated 44% efficacy for preventing injecting transmission [5] but uncertainty was wide. |
Relative risk of HCV transmission if HIV positive undiagnosed (off ART) compared to HIV negative | RRHCV_ifHIVpos | 2 (1.2–2.8) | Uniform [1–3] | |
Annual probability of HIV transmission through sex during the latent untreated stage of infection | βHIVs = 1/6* βHCV | [21] | ||
Proportion spontaneous HCV clearance among HIV negatives | ∆n | 0.25 (0.22–0.29) | Uniform [0.22–0.29] | [48] |
Relative risk of spontaneous clearance among HIV positives compared to HIV negatives | RRsponclearHIVpos | 0.68 (0.39–0.90) | Lognormal [0.46–1.0] | [49] |
MSM parameters | ||||
Number of HIV/HCV coinfected and diagnosed MSM in 2015 | 406 | HERACLES cohort (unpublished) | ||
Number of newly HIV/HCV coinfected and diagnosed MSM each year | Calculated | Based on multiplying the number of HIV-infected MSM in 2010 by the proportion of HIV+ MSM who are diagnosed, by the primary HCV incidence among HIV-infected MSM. | ||
Number of HIV-infected MSM in 2010 | θMSM | 16,281 (9,018–23,526) | Uniform [8,646-23,913] | Based on multiplying the male population over 15 years of age by the prevalence of MSM, and the prevalence of HIV-infected MSM in 2010 |
Proportion of HIV+ MSM who are diagnosed | 0.761 (0.751–0.771) | Uniform [0.75–0.772] | [53] | |
Primary HCV incidence among HIV-infected MSM (per 100 person-years) | 1.17 (0.75–1.16) | Uniform [0.73–1.61] | [54] See supplement for details. | |
HCV reinfection incidence among HIV+ MSM (per 100 person-years) | Γ | 7.07 (3.87–10.27) | Uniform [3.7–10.44] | [55] |
Background (non HIV or HCV) mortality rate among HIV/HCV-diagnosed MSM (per year) | μMSM | 0.026 |