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PWIDs in Australia. This strategy resulted in a spend of $A3.895 billion over 15 years compared with inaction,
but resulted in 132,000 quality adjusted life years (QALYs) gained. Using a willingness to pay (WTP) threshold
of $AUD50,000 per QALY, this was cost effective with an incremental cost-effectiveness ratio of $A29,614 per
QALY gained. The modelling is reproduced in Figure 1 which demonstrates the rapid reduction in incidence
and prevalence utilising this method compared treating those with established liver disease where reductions
are only modest [Figure 1].

[45]
Iceland also has a policy of universal DAA access . Iceland was also evaluated in an mathematical model
[9]
to establish key targets required to achieve the elimination objectives as stipulated by WHO . Iceland has a
population of 332,000, of which 1300 are estimated to be living with HCV. The modelling determined that
if DAA therapy was provided at current treatment levels, accompanied by unchanged HCV testing rates
amongst the PWID population, incidence would decrease by 72% by 2030, yet still short of the WHO target.
Comparatively, elimination could be achieved by 2030, 2025 or 2020, if 55/1000, 75/1000 or 188/1000 of the
country’s current PWIDs underwent HCV treatment per year. In all scenarios modelled, the elimination
targets were achieved only where treatment was scaled up amongst PWIDs. The researchers did acknowledge
that to satisfy this model, an increase in HCV diagnosis amongst Icelandic PWIDs or a 20% increase in harm
reduction services is required.

A modelling study regarding PWIDs in Montreal, Canada identified the importance of early HCV diagnosis
[46]
and prompted linkage to care . Montreal has 4000 PWIDs who are variably involved in HCV care. The
researchers established key variables in their mathematical model including the interval between acquisition
and diagnosis, time to linkage to care, lost to follow up rates, referral-to-treatment conversion and the efficacy
of treatment, defined as likelihood of SVR12. The modelling demonstrated that the greatest incidence and
prevalence reductions of 76% and 4.3/100 person years over 10 years respectively were achieved by maximising
treatments delivered to PWIDs, irrespective of fibrosis stage, and by improving the cascade of care throughput.
Comparatively, where treatments were delivered only to PWID with hepatic fibrosis or cirrhosis, incidence and
prevalence estimates were only modestly reduced as TAsP was not achieved. The TAsP principle is supported
[47]
by an alternate study which demonstrated that treating 120/1000 PWIDs per year in the USA, in a climate of
60% HCV prevalence amongst PWIDs, would achieve elimination within 10 years.

[48]
HCV TAsP is also cost-effective. Martin et al. utilised a mathematic model which evaluated the impact of
HCV therapy delivered to either PWID, ex-PWID or never-PWID in a setting of varying HCV prevalences.
The model considered the effect on transmission, interrupting liver disease progression and reinfection after
SVR12. In a climate of 40% chronic HCV infection amongst PWIDs, it was most cost effective to provide HCV
therapy to PWIDs with moderate fibrosis, followed by PWIDs with mild fibrosis. Both scenarios were more
cost effective than treating ex- or never-PWIDs due to the prevention of incident infections via transmission.
Treating PWIDs with moderate and mild fibrosis conferred the greatest net monetary benefit of £60,640 and
£59,258 respectively (where chronic HCV infection was 20% amongst PWIDs) by minimising future medical
expenditures and gaining QALYs. The cost effectiveness of this approach is in contrast to policies which limit
the use of DAAs to patients with advanced fibrosis or cirrhosis only, including in the USA, and will result in
[49]
higher ongoing HCV related costs despite the failure to control the HCV epidemic .

Modelling studies of treating PWID in prison
The role of prison-based HCV treatment programs to reduce disease prevalence within the broader commu-
[50]
nity has been demonstrated with Scottish data . The model determined 27.7% of incident HCV infections in
Scotland related to incarceration, particularly related to the heightened risk of transmission immediately post-
release. Via treatment scale up that would reach 80% of all HCV infected PWIDs with a sentence duration of >
16 weeks, this intervention alone could reduce Scotland’s incidence and prevalence by 45.6% and 45.5% respec-
tively by 2030, highlighting the key role of prison based programs to achieve elimination.