Reducing the duration of direct-acting antiviral treatment for hepatitis C will make treatment for people in prison in England highly cost-effective, and could provide an important opportunity for providing access to hepatitis C treatment for people who inject drugs, Natasha Martin of the University of California San Diego told the International Liver Congress in Vienna, Austria, last month.
Prisoners have a high prevalence of hepatitis C and people who inject drugs may be more likely to be exposed to hepatitis C during a spell in prison. This is due both to the high prevalence of hepatitis C virus (HCV) among fellow prisoners and the potential for multi-person use of non-sterile injecting equipment and drug preparation equipment, especially in prison systems where harm reduction measures are not made available.
Reducing the burden of hepatitis C among people in prison offers a potentially significant opportunity for reducing the overall burden of hepatitis C among people who inject drugs and for reducing onward transmission of hepatitis C – both among people in prison and in the community. Prison may provide an opportunity to deliver high-quality health care and supervised treatment for individuals who might otherwise lack a fixed address and have very limited engagement with medical services.
A proof-of-concept study of hepatitis C as a means of reducing onward transmission – treatment as prevention – recently began in Australia. But in many countries – including England – rates of hepatitis C testing and treatment remain very low among people in prison and among people who inject drugs.
Opt-out testing for hepatitis C was introduced in prisons in England and Wales in 2014, but the long duration of interferon-based treatment means that prisoners are often released before treatment can be completed, making the scale up of interferon-based treatment in prisons impractical.
Shorter treatment courses of 8 to 12 weeks using direct-acting antivirals would be more effective and more likely to be completed before release, but the cost-effectiveness of interferon-free regimens in prison populations is unclear.
Using a model developed to project the dynamics of HCV transmission among prison populations in England and Wales, Natasha Martin and epidemiologists at the University of Bristol calculated the cost-effectiveness of an 8- or 12-week treatment course which achieved a 95% cure rate, and also considered the effects of variations in the rate of testing, referral to treatment and treatment initiation.
The model assumed that it would be possible to test 1.5% of the prison population each week, of whom 15% would be diagnosed with hepatitis C. The assumed prevalence is based on recent sampling, but antibody testing among people in prison in England and Wales between 2005 and 2008 found a mean prevalence of 25% among those referred for testing. No anonymised seroprevalence survey has been carried out since 1997.
Just over half (56%) of those diagnosed would be referred for treatment, and of these 25% of people who formerly injected drugs and 2.5% of people currently injecting drugs would start treatment within two months of diagnosis. This estimate takes into account treatment completion rates too: on average, people currently injecting drugs will spend an average of four months in prison, while former drug users will spend an average of eight months in prison.
The model assumed a regimen cost of £3200 per week for direct-acting antivirals, the currently anticipated cost for sofosbuvir and ledipasvir (Harvoni) in England and Wales, and a cure rate of 95%.
The model showed that doubling prison testing rates and following the assumptions of the model regarding treatment uptake would result in an incremental cost-effectiveness ratio of £25,766 per quality-adjusted life-year (QALY) gained for direct-acting antiviral treatment compared to interferon-based treatment. This level is considered cost-effective in England and Wales.
Doubling the rate of treatment would reduce the cost-effectiveness ratio to £21,678 per QALY, while reducing the duration of treatment to eight weeks would cause the cost-effectiveness ratio to fall to £12,323, making treatment highly cost-effective. If 25% of people who inject drugs were treated as a result of referral, the cost-effectiveness would fall to around £5000. However, the affordability of scaling up treatment for all who need it is unclear, said Natasha Martin.
Martin N et al. Is increased HCV case-finding combined with 8 or 12 week interferon-free direct-acting antiviral treatment cost-effective in UK prisons? A cost utility analysis including treatment as prevention benefits. J Hepatology 62 (50th International Liver Congress), S255, abstract 0124, 2015.