Garvey's team looked at trends in the incidence of
acute HCV infection among HIV-positive MSM between July 2013 and June 2018,
spanning the transition from the interferon era to the DAA era. Prior modelling
studies have made projections about changes in the HCV epidemic; the present
work analysed real-world experience.
This retrospective study included around 6000
HIV-positive men at risk for hepatitis C seen at three central London clinics: Royal
Free NHS Trust, St Mary's Hospital of the Imperial College NHS Trust and
Mortimer Market Centre, a sexually transmitted infection clinic.
As
of 2016, the NHS offers access to HCV treatment at any stage of liver disease,
but does not permit initiation of treatment for acute infection within the
first six months (the window in which some people will clear the virus naturally)
or a second course of DAAs for those who are re-infected. However, all three
clinics were involved in clinical trials that provided treatment without these
restrictions.
Every six months the researchers collected data on the number of first
acute HCV diagnoses and subsequent diagnoses of acute HCV re-infection after
treatment or spontaneous clearance, as well as the number of people treated and
whether they received DAAs or interferon-based therapy.
The
researchers identified 256 diagnoses of acute HCV infection during the study
period; of these, 111 were first infections and 45 were re-infections. The
median age at the time of diagnosis was 43 years. Three-quarters had HCV
genotype 1a, followed by genotype 4 (11%), genotype 3 (7%) and genotype 1b
(4%). An increasing proportion of men were on antiretroviral therapy (ART) with
undetectable HIV viral load, reaching 100% on ART and 94% with viral
suppression in 2018.
The
rate of new HCV infections peaked in 2015, at 17 cases per 1000
person-years
(PY). First acute infections – excluding re-infections – peaked the same
year, at
15 per 1000 PY. After that, the rates declined steeply and steadily,
falling to six total new infections and three first infections per 1000
PY in 2018. This
represents a 68% reduction in new HCV infections overall and a 79% drop
in
first infections, according to Garvey.
The
decline in London is similar to the drop in acute HCV infections in Amsterdam, which
fell from 11 per 1000 PY in 2014 to 6 per 1000 PY in 2016, as
reported at CROI 2017. However, this still does not meet the WHO goal of a 90% reduction,
or 1.7 infections per 1000 PY.
The
proportion of re-infections relative to all acute infections rose over time,
from less than a tenth (9%) in 2013 to nearly half (47%) in 2018. The treatment
pathway also shifted during the study period. From 2013 to 2016, a majority of
patients received or were awaiting DAAs through the NHS programme, starting
therapy an average of 23 months after diagnosis. From 2016 onward, a majority
were treated in clinical trials, waiting an average of 10 months.
During
the earliest years of the study, people delayed treatment by more than two
years, likely reflecting "warehousing" as patients eschewed
interferon-based therapy while waiting for DAAs to become available. This
longer wait may have increased transmission due to longer duration of active
infection, Garvey explained
"In this large London cohort of HIV-positive MSM, we have observed
a sharp decline in new acute HCV diagnoses since peak in late 2015 with no
change to screening practices," the researchers concluded.
However,
Garvey cautioned that HCV re-infection
remains high and may be increasing, highlighting the need for better risk
reduction strategies and determination of appropriate screening
policies for HIV-positive and HIV-negative gay and bisexual men. Further, she said,
the opportunity for 'microelimination' may be lost without the ability to treat
people in the first months after acute infection and to treat re-infections.