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.
Quality adjusted life year. Used in studies dealing with cost-effectiveness and life expectancy, this gives a higher value to a year lived with good health than a year lived with poor health, pain or disability.
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
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
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.