Reducing the burden of hepatitis C virus (HCV) related liver disease will require treating people who inject drugs (PWID), the group at most risk of infection and transmission. We determine the cost-effectiveness of treating PWID with interferon-free direct-acting antiviral therapy in Australia.

Using a deterministic model of HCV treatment and liver disease progression, including a fixed rate of re-infection, the expected healthcare costs and quality-adjusted life years (QALYs) of a cohort of newly HCV-infected PWID were calculated for: no treatment; treatment after initial infection ("early-treatment"); and treatment prior to developing compensated cirrhosis ("late-treatment"). Incremental cost-effectiveness ratios (ICERs) were used to compare scenarios.

Late-treatment was cost-effective compared to no treatment, with a discounted average gain of 2.98 (95%confidence interval 2.88-5.22) QALYs per person for an additional cost of $15,132 ($11,246-18,922), giving an ICER of $5078 ($2847-5295) per QALY gained. Compared to late-treatment, early-treatment gained a further discounted average of 2.27 (0.58-4.80) QALYs per person for $38,794 ($34,789-41,367), giving an ICER of $17,090 ($2847-63,282), which was cost-effective in approximately 90% of Monte-Carlo uncertainty simulations. For every 100 newly HCV-infected PWID, there were an estimated 40 (39-56) eventual liver-related deaths without treatment, compared to 7 (6-11) and 8 (7-13) with early-treatment and late-treatment available respectively.

Treating HCV-infected PWID with new therapies is cost-effective and could prevent a significant number of liver-related deaths. Although late-treatment was the most cost-effective option, the cost per QALY gained for early-treatment compared to late-treatment is likely to be below unofficial Australian willingness to pay thresholds.