Association between rapid utilisation of direct hepatitis C antivirals and decline in the prevalence of viremia among people who inject drugs in Australia

Background & Aims: The World Health Organization (WHO) established targets to eliminate hepatitis C virus (HCV) infection as a public health threat by 2030. Evidence that HCV treatment can lower viraemic prevalence among people who inject drugs (PWID) is limited. Broad accessibility of direct-acting antiviral (DAA) therapy in Australia, since March 2016, provides an opportunity to assess the efficacy of these treatments at a population level in a real-world setting.

Methods: Data from Australia’s annual bio-behavioural surveillance examined treatment uptake and estimated viraemic prevalence among PWID attending needle syringe programs nationally between 2015 and 2017. Multivariate logistic regression identified variables independently associated with HCV treatment among those considered eligible (anti-HCV positive excluding HCV RNA negative with no self-reported history of HCV treatment) in 2017.

Results: Annual samples ranged from 1,995–2,380 PWID. Anti-HCV prevalence declined from 57% (2015) to 49% (2017, χ2 p trend <0.001), with 40–56% of anti-HCV positive respondents providing sufficient sample for HCV RNA testing. Between 2015 and 2017, treatment uptake among those eligible increased from 10% to 41% (χ2 p trend <0.001) and viraemic prevalence among the overall sample declined from 43% to 25% (χ2 p trend <0.001). In multivariable analysis, older age (≥50 years adjusted odds ratio [aOR] 1.82; 95% CI 1.09–3.06;p = 0.023 and 44–49 years aOR 1.75; 95% CI 1.03–3.00;p = 0.038 vs. ≤37 years) and history of opioid substitution therapy (aOR 2.06; 95% CI 1.30–3.26; p = 0.002) were independently associated with treatment.

Conclusions: This study confirms PWID are willing to initiate treatment when HCV DAA therapy is available and provides population-level evidence of a decline in viraemic prevalence among people most at risk of ongoing HCV transmission. Scaled up surveillance and monitoring are required to evaluate progress toward WHO HCV elimination goals.

Lay summary: The World Health Organization’s goal to reduce hepatitis C virus incidence by 80% will be difficult to achieve without widespread scale up and a corresponding reduction in viraemic prevalence among those most at risk of onward transmission. Our results indicate that a population-level reduction in viraemic prevalence is achievable through high levels of treatment and cure among people who inject drugs.