Targeting new
hepatitis C virus (HCV) direct-acting antivirals (DAAs) at patients with
cirrhosis will substantially reduce short-term incidence of end-stage liver
disease (ESLD) and liver cancer (HCC) in England, according to a model published in
the Journal of Viral Hepatitis.
However, this strategy would have no meaningful impact on incidence of new HCV
infections among people who inject drugs (PWID), the main HCV risk group. Effective
use of new HCV therapies as prevention would require the treatment of patients
with only mild liver disease.
“These analyses
suggest that targeting new DAAs to people with cirrhosis will result in a rapid
reduction in incident cases of ESLD/HCC within 2 – 3 years, to around half of that
currently predicted in 2020, but with little impact on HCV incidence among
PWID,” comment the authors.
Moreover, only
targeting patients with cirrhosis would not be sufficient to a medium-term
increase in severe liver-related disease. “Due to lower SVR [sustained
virologic response] rates in those with cirrhosis, continued post-SVR
progression (albeit at a low rates) and rising numbers developing cirrhosis,
treating those at moderate disease stage is also required to prevent a rebound
in incident cases of ESLD/HCC,” explain the investigators.
The implications
of the investigators’ models are clear: targeting patients with cirrhosis alone will not be enough to achieve either a sustained reduction in the incidence of
serious HCV-related liver disease or reductions in HCV incidence among the main
risk group.
“With a budget of
£190 million for new DAAs announced in June 2015 and current focus on treating
those with cirrhosis, only the short-term goal of reducing ESLD/HCC over the
next five years can be achieved,” they write. “Reductions in HCV
transmission…will require a change in strategy to treat substantial numbers of
active PWID, most of whom have relatively mild disease.”
HCV-related liver
disease is a growing public health problem in the UK. New diagnoses of serious
liver disease related to HCV have increased from 574 per year in 1998 to 2652
per year in 2014; reported deaths due to such complication have risen more than
fourfold since 1996. It has been estimated that by 2030, HCV will be the
underlying cause of up to 1500 cases of ESLD each year.
However, new HCV
treatments have the potential to transform the course of the epidemic. In both
clinical trials and “real world” settings, combinations of DAAs have achieved
SVR rates of 90% or more.
These new
therapies are expensive, a single course of therapy costing at least £30,000.
In 2015 the NHS in England allocated £190 million for their use, prioritising
patients with cirrhosis.
Investigators
wanted to determine the potential impact of targeted use of DAAs on the England’s
HCV epidemic.
They therefore
designed two models.
The first
estimated the impact of treating various stages of HCV-related liver disease –
cirrhosis, moderate fibrosis, mild fibrosis. A second model was used to
determine the impact of DAA use on incidence and prevalence of chronic HCV
among PWID, the main HCV risk group in England.
In the first
model, treatment of 3500 patients with cirrhosis each year from 2015 was predicted
to reduce the incidence of ESLD/HCC from 1110 cases per year in 2015 to 630
cases per year by 2020. Over ten years, 6350 cases of ESLD/HCC were predicted
with the use of DAAs, compared to 12,510 with use of older interferon-based therapies.
However, a risk of
continued disease progression and a diminishing pool of patients with cirrhosis
would mean that eligibility for treatment would have to be expanded to patients
with mild fibrosis to sustain these reductions.
Treating an
additional 5000 patients with moderate fibrosis per year from 2016 was sufficient to
prevent incident cases of ESLD/HCC rebounding to above 600 cases per year, with a slow decline in disease progression from 2025. This strategy would prevent
an additional 660 cases of serious liver disease – on top of that achieved by
treating patients with cirrhosis – over ten years.
Further scale-up
to encompass patients with mild fibrosis had limited additional benefit,
preventing only 16 additional cases of ESLD/HCC by 2025.
The prevention
model assumed that 34% of PWID in England are chronically infected with HCV and
that 4.8% of this population is newly infected with the virus each year.
Treating only
patients with cirrhosis had very limited impact on both prevalence and
incidence. Only 7474 PWID would be treated over 15 years, reducing prevalence
modestly to 32% and incidence to 4.4% by 2030.
Treating an
additional 2500 PWID with moderate HCV-related liver fibrosis would reduce
prevalence to 24% and incidence to 2.8%. However, the model showed that the
biggest impact on the epidemic would be achieved if treatment strategies were
extended to include patients with mild fibrosis, which would reduce prevalence
to 11% and incidence to 1.4%.
“With the arrival
of new DAA treatments, the outlook is extremely good for HCV-infected patients,
with the risk of severe HCV-related liver disease being markedly reduced,”
conclude the authors. “Focusing solely on cirrhotics is not a tenable long-term
strategy if continued reductions in incident cases are to be achieved. NHS
England is currently rolling out new DAAs for those with cirrhosis, but
treatment of other groups will need to follow quickly.”