The impact and cost-effectiveness of scaling up HCV treatment for achieving elimination among people who inject drugs in England: a synopsis including evidence synthesis and economic modelling.

Background: People who inject drugs are disproportionately affected by hepatitis C virus. The emergence of direct-acting antiviral treatments for hepatitis C virus motivated England to achieve the World Health Organization's elimination target of decreasing hepatitis C virus incidence among people who inject drugs to < 2 per 100 person-years (/100 person-years) by 2030. We determined whether existing testing and treatment strategies will reach this target in England, or whether improved strategies are needed and whether they are cost-effective. Methods: A dynamic hepatitis C virus transmission model among people who inject drugs was developed for four English regions. The model included the pathway from testing to treatment in prisons, drug treatment centres and other settings. Each pathway was parameterised using region-specific data, with yearly bio-behavioural surveys among people who inject drugs being used to parameterise and calibrate the model in a Bayesian framework. The model projected whether each region will reach the hepatitis C virus incidence target or what improvements (in testing and linkage to treatment) are needed from 2024 to achieve it. Hepatitis C virus care pathway costs were collated through interviews with practitioners and the published literature. The mean incremental cost-effectiveness ratio (per quality-adjusted life-year saved) was estimated for any 'improved' strategy that reached the incidence target compared to the baseline strategy. Incremental cost-effectiveness ratios were compared to a willingness-to-pay threshold of £20,000/quality-adjusted life-year saved over a 50-year time horizon (3.5% annual discount rate). Results: Across the four regions over 2016-22, an estimated 8831-9689 treatments occurred among 37,230 people who inject drugs, with the annual number treated increasing in prisons (7.8 times) and drug treatment centres (3.6 times). Model projections suggest that hepatitis C virus incidence among people who inject drugs has decreased across the regions by 56.1-85.4% (range of medians) over 2015-22, with incidence decreasing by 79.7-98.6% to 0.2-2.2/100 person-years by 2030. The World Health Organization incidence target (< 2/100 person-years) will be reached with > 80% probability in three regions and 40% probability in the other region. The probability of reaching the incidence target increases to > 65% in this region if screening is increased in drug treatment centres (80% screened annually) or prisons (75% of people get tested during their prison stay), with these screening strategies being cost-effective. Conclusion: Numerous England regions may be on target to decrease hepatitis C virus incidence among people who inject drugs to < 2/100 person-years. In regions that are not on target, further scale-up of testing in drug treatment centre or prison from 2024 could enable them to reach the World Health Organization elimination target and be cost-effective. Limitations: Projections were based on model estimations, which need to be confirmed with empirical data. Data uncertainties affected our model projections, including uncertainty in the number of people who inject drugs in each region and the number of treatments given to people who inject drugs in different settings. Sample sizes for the yearly bio-behavioural surveys among people who inject drugs were small, and so samples were pooled over multiple years. Testing rates among people who inject drugs could not be directly estimated because the sentinel surveillance had incomplete coverage and could not identify people who inject drugs; testing rates were estimated through model calibration. Future work: There is interest in understanding what scale-back in testing can occur after 2030 without resulting in a rebound in hepatitis C virus incidence, and in developing models for each devolved nation to determine their progress to World Health Organization hepatitis C virus elimination targets. Funding: This synopsis presents independent research funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme as award number NIHR128513.