Table 1 Model parameters and Sources

Calibrated parameter

Number of diagnosed and in care HIV-infected and chronic HCV coinfected (HIV+/HCV+) in 2015

HCV chronic prevalence among PWID injecting for < 10 years in 2010

HCV chronic prevalence among PWID injecting for > 10 years in 2010

HIV prevalence among PWID injecting for <10 years, in 2010

HIV prevalence among PWID injecting for > 10 years in 2010

HCV chronic prevalence among HIV+ ever PWID in 2015

Proportion of HIV+/HCV+ diagnosed individuals who are current PWID in 2015

Proportion HIV+/HCV+ diagnosed ever PWID who had previously failed HCV treatment in 2015

Parameter Definition

Symbol

Sampled Value and 95% Interval

Sampling Distribution

Source

Sustained HCV viral response, monoinfected on DAAs

1- f_md

0.9

[2]

Sustained HCV viral response, coinfected on DAAs

1- f_cd

0.948

HERACULES cohort

Sustained HCV viral response, monoinfected pre-DAAs

1- f_mpd

0.52 (0.45–0.60)

Uniform [0.45–0.60]

Pooled SVR weighted by genotype and genotype distribution [30, 31].

Sustained HCV viral response, coinfected pre-DAAs

1- f_cpd

0.30 (0.20.-0.39)

Uniform [0.20–0.40]

Pooled SVR weighted by genotype and genotype distribution [30, 32].

Excess death rate due to mono-infection with HIV untreated per year

μ_uHIV

0.097 (0.09–0.10)

Uniform [1/9.6–1/11.5]

[33]

Decreased mortality hazard ratio for HIV on ART

μ_HIV

0.26 (0.20–0.32)

Uniform [1/5–1/3]

[34, 35]

Excess death rate due to chronic HCV mono-infection per year

μ_HCV

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)

[36, 37]

Excess death rate due to HCV for HIV-HCV co-infection with no HIV treatment per year

μ_HCVuHIV

0.0042 (0.0039–0.0046)

Uniform [0.0038–0.0046]

[36, 37]

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

[36, 37]

Excess death rate due to HIV for HIV-HCV co-infection with no HIV treatment per year

μ_uHIVHCV

0.0005 (0.00041–0.00066)

Uniform [0.0004–0.00069]

[36]

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]

8.4 million Andalusia population in 2010, 92% > age 15, and a PWID prevalence among adults of 0.1% (national estimate) [38, 39],

HCV treatment rate among PWID who are HIV- or HIV+ and undiagnosed (%/year)

r, r_hu

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)

r_hd

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)

r_hd

33%

HERACLES cohort (unpublished data from 2015 to 2017)

Average duration of injecting until final cessation (years)

1/μ_cd

15.1 (6.8–24.4)

Uniform

[5–25]

Uncertain, so vary widely [41, 42]

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

μ_IDU

0.0062 (0.005–0.007)

Uniform [0.0053–0.0070]

[44]

Relative risk of HIV transmission through sex for those on ART

RR_HIVs

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

RR_HIVi

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

RR_{HCV_ifHIVpos}

2 (1.2–2.8)

Uniform [1–3]

[46, 47]

Annual probability of HIV transmission through sex during the latent untreated stage of infection

β_HIVs = 1/6* β_HCV

[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

RR^{sponclearHIVpos}

0.68 (0.39–0.90)

Lognormal [0.46–1.0]

[49]

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

θ_MSM

16,281 (9,018–23,526)

Uniform

[8,646-23,913]

[50,51,52]

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)

μ_MSM

0.026

Average life expectancy in Spain of 80.7 [56], and average age at HIV/HCV diagnosis of 43 [57].