Estimating the number of new hepatitis C infections in Australia in 2015, prior to the scale-up of direct-acting antiviral treatment

Incidence of primary hepatitis C virus infection among people who inject drugs in Australia pre- and post-unrestricted availability of direct acting antiviral therapies

AIMS

The 2016 Global Health Sector Strategy (GHSS) on viral hepatitis aims to reduce new hepatitis C virus (HCV) infections by 80% by 2030, including a 30% reduction by 2020. This study aimed to estimate primary HCV incident infection among a national sample of people who inject drugs (PWID) before and after the introduction of unrestricted access to HCV direct-acting antiviral (DAA) therapy via Australia's Pharmaceutical Benefits Scheme in 2016.

DESIGN

A simple deterministic linkage method identified repeat respondents in serial cross-sectional surveys conducted among PWID. Two separate retrospective cohorts of HCV antibody-negative respondents were created, corresponding to the pre- (2010-15) and post- (2016-21) DAA time-periods.

SETTING AND PARTICIPANTS

This study took place in Australia. Among 757 PWID retained (376 pre-DAA, 381 post-DAA), more than half were male (60%), the majority were heterosexual (80%), the median age was 40 years (interquartile range = 33-46 years) and the predominant drugs last injected were heroin (24%), pharmaceutical opioids (27%) and methamphetamine (41%).

MEASUREMENTS

The primary outcome was HCV seroconversion, defined as a negative HCV antibody test result followed by a positive HCV antibody result. Time to primary incident HCV infection was estimated using the person-years (PY) method.

FINDINGS

A total 97 of 376 (2010-15) and 41 of 381 (2016-21) HCV seroconversions were identified. Primary HCV incidence more than halved, from 13.6 per 100 PY [95% confidence intervals (CI) = 11.2, 16.6] in 2010-15 to 5.4 per 100 PY (95% CI = 3.9, 7.3) in 2016-21. The decline was independent of observed differences in demographic and drug use characteristics over the two time-periods (adjusted hazard ratio = 0.47, 95% CI = 0.31-0.69, P < 0.001).

CONCLUSIONS

Australia has had a 53% reduction in primary hepatitis C virus (HCV) incidence among people who inject drugs following unrestricted availability of HCV direct acting antiviral therapy in March 2016. Given that PWID are the predominant population at risk of HCV infection in Australia, findings add to the evidence that Australia has probably met its 2020 Global Health Sector Strategy subtarget of a 30% decline in new infections.

Hepatitis C incidence among patients attending primary care health services that specialise in the care of people who inject drugs, Victoria, Australia, 2009 to 2020

BACKGROUND

Monitoring trends in hepatitis C virus (HCV) incidence is critical for evaluating strategies aimed at eliminating HCV as a public health threat. We estimate HCV incidence and assess trends in incidence over time among primary care patients.

METHODS

Data were routinely extracted, linked electronic medical records from 12 primary care health services. Patients included were aged ≥16 years, tested HCV antibody negative on their first test recorded and had at least one subsequent HCV antibody or RNA test (January 2009-December 2020). HCV incident infections were defined as a positive HCV antibody or RNA test. A generalised linear model assessed the association between HCV incidence and calendar year.

RESULTS

In total, 6711 patients contributed 17,098 HCV test records, 210 incident HCV infections and 19,566 person-years; incidence was 1.1 per 100 person-years (95% confidence interval (CI): 0.9 to 1.2). Among 559 (8.2%) patients ever prescribed opioid-related pharmacotherapy (ORP) during the observation period, 135 infections occurred during 2,082 person-years (incidence rate of 6.5 per 100 person-years (95% CI: 5.4 to 7.7)). HCV incidence declined 2009-2020 overall (incidence rate ratio per calendar year 0.8 (95% CI: 0.8 to 0.9) and among patients ever prescribed ORT (incidence rate ratio per calendar year 0.9, 95% CI: 0.75 to 1.0).

CONCLUSION

HCV incidence declined among patients at primary care health services including among patients ever prescribed ORP and during the period following increased access to DAA therapy.

SUMMARY

Among a retrospective cohort of ∼6,700 primary care health services patients, this study estimated a hepatitis C virus (HCV) infection incidence of 1.1 per 100 person-years (95% confidence interval: 0.9 to 1.2). HCV infection incidence declined between 2009 and 2020.

Assessment of the cost-effectiveness of Australia's risk-sharing agreement for direct-acting antiviral treatments for hepatitis C: a modelling study

Background

Hepatitis C elimination may be possible with broad uptake of direct-acting antiviral treatments (DAAs). In 2016 the Australian government committed A$1.2 billion for five years of unlimited DAAs (March 2016 to February 2021) in a risk-sharing agreement with pharmaceutical companies. We assess the impact, cost-effectiveness and net economic benefits likely to be realised from this investment.

Methods

Mathematical modelling to project outcomes for 2016-2030 included: (S1) a counter-factual scenario (testing/treatment maintained at pre-2016 levels); (S2) the current status-quo (testing/treatment as actually occurred 2016-2019, with trends maintained to 2030); and (S3) elimination scenario (S2 plus testing/treatment rates increased between 2021-2030 to achieve the WHO elimination targets).

Findings

S1 resulted in 68,800 new hepatitis C infections and 18,540 hepatitis C-related deaths over 2016-2030. The total health system cost (HCV testing, treatment, disease management) was A$3.01 billion and the cost of lost productivity due to absenteeism, presenteeism and premature deaths was A$26.14 billion. S2 averted 15,700 (23%) new infections and 8,500 (46%) deaths by 2030, with a total health system cost of A$3.48 billion, A$472 million more than S1 (A$1.65 billion more in testing/treatment but A$1.20 billion less in disease costs; A$5,752 per QALY gained from a health systems perspective). Productivity loss over 2016-2030 was A$19.96 billion, A$6.17 less than S1, making S2 cost-saving from a societal perspective by 2022 with a net economic benefit of A$5.70 billion by 2030. S3 averted an additional 10,000 infections and 930 deaths compared with S2 and increased the longer-term economic benefit.

Interpretation

Five years of unrestricted access to DAAs in Australia has led to significant health benefits and is likely to become cost-saving from a societal perspective by 2022.

Funding

Burnet Institute