EASL 2015: Hepatitis C Treatment Could Cut HCV Transmission Among UK Gay Men in Half

alt

Access to more effective hepatitis C treatment could reduce new infections among men who have sex with men in the United Kingdom by half over the next decade, according to a mathematical modeling study presented at the European Association for the Study of the Liver (EASL) International Liver Congress in Vienna in April.

[Produced in collaboration with Aidsmap.com]

The model found that if 80% of men who have sex with men (MSM) are treated within a year of acquiring hepatitis C virus (HCV), and 20% of those with chronic infection are treated each year, incidence would be halved and the prevalence of HCV among MSM with HIV would fall below 3% by 2025.

Epidemics of hepatitis C have emerged among HIV-positive men who have sex with men in Europe, North America, and Australia over the past decade. Studies of risk factors for HCV infection among MSM consistently show an association with unprotected anal intercourse, rectal bleeding, fisting, and sex with multiple partners (van de Laar 2010).

Sharing equipment to inject methamphetamine and other stimulants during sex sessions has also been identified as a possible risk factor, but it is important not to overstate the role of injection drug use in transmitting HCV between gay men. Recent studies in the U.K. and U.S. show that the vast majority of men newly diagnosed with hepatitis C have no history of injection drug use (Ward 2014; Garg 2013).

Other drug use appears to play an important role in HCV transmission among MSM. Some studies have found that sharing straws for snorting drugs is associated with acute infection. A large study of HIV-positive MSM in the U.K. found that HCV acquisition was associated with a history of using GHB and nitrites (poppers), both of which may be used during anal intercourse and sex parties.

Sharing sex toys and having ulcerative sexually transmitted infections, usually syphilis, have also been associated with acute HCV infection in this population.

What almost all these factors have in common is their contribution to making blood-to-blood contact more likely during sexual activity. Many of these factors are likely to be synergistic; for example, use of GHB at a sex party may permit prolonged anal intercourse with multiple sex partners, leading to bleeding and rectal trauma.

Although the risk of HCV infection can be minimized by condom use and safe injecting practices, epidemiologists have suggested that hepatitis C incidence will only be checked among MSM and people who inject drugs by reducing hepatitis C prevalence through curative treatment -- treatment as prevention.

To estimate the potential effect of treatment on HCV incidence and prevalence among MSM in the U.K., Natasha Martin from the University of California San Diego and colleagues in the U.K. developed a model of HCV transmission among MSM using data from the UK Collaborative HIV Cohort (UK CHIC) and surveillance data on HCV infections.

The model assumed that 80% of men treated within a year of HCV infection (acute cases) and 35% of men with chronic infection would be cured using interferon-based therapy, and that 90% of all men would be cured using new interferon-free direct-acting antiviral regimens. The model assumed as a base scenario that 39% of newly infected men and 5% of chronically infected men would be treated each year.

Approximately 8.6% of MSM with diagnosed HIV infection were estimated to have hepatitis C in 2015. If current trends continue, and rates of treatment of newly infected men persist at a low level according to the base scenario, hepatitis C prevalence will increase to 10.8% by 2025, assuming that HIV diagnoses also continue to rise over the same period.

However, even a low rate of hepatitis C treatment would have an effect on prevalence. Without any treatment at all, prevalence would have reached 11.6% in 2015 and would rise to 17% in 2025.

Scaling up treatment to treat 80% of newly infected men and 20% of all chronic cases per year would reduce prevalence to under 3% by 2025, and would halve new infections, to less than 0.5 per 100 person years of follow up.

The model did not look at cost-effectiveness, and the researchers say that this is their next step. They also want to look at the impact of HCV transmission from people with undiagnosed HIV infection to HIV-negative people, and to look at whether HCV transmission is having any effect on HIV transmission, and vice versa.

6/17/15

Reference

NK Martin, M Hickman, M Nelson, et al. Understanding and preventing the HCV epidemic among men who have sex with men in the UK: a mathematical modelling analysis. 2015 International Liver Congress: 50th Annual Meeting of the European Association for the Study of the Liver (EASL). Vienna, April 22-26, 2015. Abstract P1289.