Treatment using
direct-acting agents (DAA) could have a major impact on the hepatitis C virus
(HCV) epidemic in the United States, according to a model published in the online
edition of Clinical Infectious Diseases.
A four-fold increase in treatment rates could prevent over a quarter of a million
HCV-related deaths by 2040, and prevalence could be reduced by 90% with the
scaling up of screening efforts, especially the targeting of people who inject
drugs (PWID). But the investigators caution that elimination of the epidemic
with DAAs would require near-universal testing and a 20% annual treatment rate.
“We found that HCV
prevalence, HCV-associated liver disease, and HCV-associated mortality in the
United States can be substantially reduced through widespread treatment with
DAAs,” write the researchers. “Up to 150,000 additional cases could be
identified by increasing HCV screening, effectively eliminating HCV from the
noninjecting population. Further opportunities exist to greatly reduce
prevalence and new infections among PWIDs through targeted screening and
treatment.”
An estimated 5
million individuals in the United States have chronic HCV infection. More than
half are unaware of their status, including two-thirds of people who inject drugs who have HCV,
the population most affected by HCV.
DAAs have
transformed the treatment of DAAs, achieving cure rates in excess of 90%. They
have both individual and public health benefits: reducing rates of
liver-related illness and death, and also preventing transmissions.
However, the full
benefit of DAAs is likely to be compromised because of low rates of screening
and treatment uptake, especially among people who inject drugs.
A team of
investigators therefore developed a model to calculate the potential impact of
current and enhanced levels of treatment and screening on the HCV epidemic
through to 2040.
The model was
based on epidemiological data collected between 1992 and 2014. It took into
account age-related prevalence and transmission mode. The impact of enhanced
screening beyond current populations (a guideline issued in 2012 recommended the
routine testing of those born between 1945 and 1965) and also expansion of treatment
rates. The investigators also modelled the rates of testing and treatment
required to control the epidemic among people who inject drugs.
Approximately 100,000
individuals each year currently access HCV therapy. If this figure remained
unchanged, there would be almost 900,000 new infections and over 800,000
HCV-related deaths by 2040. However, overall prevalence would also fall by 80%.
If annual treatment
increased to 200,000, 300,000 or 400,000, the 80% reduction would be achieved
by 2031, 2028 or 2025, respectively.
Increasing
treatment rates would also achieve significant improvements in liver-related
illness and death. Doubling rates would prevent approximately 290,000 new cases
of cirrhosis and 140,000 liver-related deaths. A four-fold increase would avert
over 500,000 new cirrhosis diagnoses and in excess of 250,000 deaths.
Without an
expansion of screening, at least 462,000 HCV cases would go untreated.
Universal screening of individuals who do not inject drugs was shown to have
the potential to reduce prevalence to 300,000 cases. Reducing prevalence below
this level would require a targeted offer of testing among people who inject drugs.
Currently, the
annual screening rate in this population is a little over 4%. If unchanged, by
2040 the total prevalence among people who inject drugs would fall by at most 53% and the annual rate
of new infections would fall by no more than 15%. A reduction in prevalence of
90% among people who inject drugs would require annual screening and treatment rates of 20% and
30%, respectively.
“DAAs hold
tremendous promise of improving health outcomes and reducing transmissions,”
conclude the authors. “Our analysis provides a forecast for the potential
impact of DAAs in reducing HCV-associated liver disease, demonstrating that
achievable expansion of HCV treatment at current screening rates can
substantially reduce morbidity and mortality.”