To evaluate the potential impact of
various hepatitis C screening strategies in men who have sex with men in
the UK, researchers from Bristol University, University of California
San Diego, London School of Hygiene and Tropical Medicine and the
National Institute for Health and Care Excellence constructed a model of
hepatitis C and HIV transmission and PrEP use among gay and bisexual
men in the UK.
The model examined the impact of varying levels of
PrEP coverage and screening for hepatitis C every six or 12 months and
took account of the impact of a 50% reduction in condom use.
model assumed an HIV prevalence among gay and bisexual men of 4.7% and a
hepatitis C prevalence among men with HIV of 9.9%. Prevalence among
HIV-negative men was 1.2%. The model also assumed that by 2017, 98% of
HIV-diagnosed men would be on antiretroviral treatment, 97% would be
virally suppressed and the average HIV testing frequency for
HIV-negative men would be 2.3 years. The model also assumed that,
without additional screening, hepatitis C would not be diagnosed in
HIV-negative men for between five and 15 years.
The model tested
the impact of varying levels of PrEP coverage and hepatitis C screening
in HIV-negative men on hepatitis C elimination and hepatitis C incidence
from 2018 to 2030.
In the first scenario, PrEP coverage reached
12.5% of HIV-negative men by the end of 2020 and men received PrEP for
an average of 8.2 months. Condom use in PrEP users was reduced by 50%.
PrEP services did not screen for hepatitis C.
The model found that
in this scenario, reaching 12.5% of HIV-negative men with PrEP would
have only a modest impact on hepatitis C incidence. Direct-acting
antiviral therapy for HIV-positive men with hepatitis C would have a
greater effect on hepatitis C prevalence, as curing hepatitis C would
prevent onward transmission.
"Elimination targets are not possible through only screening HIV-diagnosed MSM (as most elimination initiatives are doing)."
hepatitis C screening of all PrEP users would reduce hepatitis C
incidence among PrEP users by 65 to 70% depending on whether screening
took place every 12, 6 or 3 months. The model assumed that all men
diagnosed with hepatitis C would be treated within 2.2 years and that
95% would be cured.
Hepatitis C incidence in the wider population
of gay and bisexual men would fall to a similar extent, as high-risk
HIV-positive men (those with 15 or more anal sex partners a year, many
of whom are PrEP users) are the primary drivers of hepatitis C
transmission in the population of men who have sex with men.
PrEP users every three months and reducing the interval between
diagnosis and hepatitis C treatment to six months in this group would
reduce hepatitis C incidence by 80% but would not be enough to achieve
the World Health Organization target of a 90% reduction in incidence by
2030, especially if condom use among PrEP users fell by 50%. Additional
screening of HIV-negative men with fewer sexual partners, not using
PrEP, would be needed at least once every five years to achieve the
target, the model found.
A higher PrEP coverage of 25% and
concomitant screening for hepatitis C would be enough to reduce
hepatitis C incidence among gay and bisexual men by 90% by 2030.