Hepatitis C virus transmission among HIV-infected men who have sex with men: Modeling the effect of behavioral and treatment interventions.
Salazar-Vizcaya L et al
Hepatology 2016 Dec;64(6):1856-1869.

Abstract:
The incidence of hepatitis C virus (HCV) infections among HIV-infected men-who-have-sex with-men (MSM) increased in recent years and is associated with high-risk sexual behavior.
Behavioral interventions that target high-risk behavior associated with HCV transmission and treatment with direct-acting antivirals(DAAs) may prevent further HCV infections.

We predicted the effect of behavioral and treatment interventions on HCV-incidence and -prevalence among HIV-infected MSM up to 2030 using a HCV transmission model parameterized with data from the Swiss HIV Cohort Study. We assessed behavioral interventions associated with further increase, stabilization and decrease in the size of the population with high-risk behavior. Treatment interventions included increase in treatment uptake and use of DAAs.

If we assumed that without behavioral interventions high-risk behavior spread further according to the trends observed over the last decade, and that the treatment practice did not change, HCV-incidence converged to 10.7/100 person-years(py). All assessed behavioral interventions alone resulted in reduced HCV transmissions. Stabilization of high-risk behavior combined with increased treatment uptake and the use of DAAs reduced incidence by 77%(from 2.2 in 2015 to 0.5/100 py) and prevalence by 81%(from 4.8% in 2015 to 0.9%) over the next 15 years. Increasing treatment uptake was more effective than increasing treatment efficacy to reduce HCV-incidence and -prevalence. A decrease in high-risk behavior, led to a rapid decline in HCV-incidence, independent of treatment interventions.

Conclusion:
Treatment interventions to curb the HCV epidemic among HIV-infected MSM are effective if high-risk behavior does not increase as it has during the last decade. Reducing high-risk behavior associated with HCV transmission would be the most effective intervention for controlling the HCV epidemic, even if this was not accompanied by an increase in treatment uptake or efficacy.

Expert's Commentary

« In the MSM community, outbreaks of acute HCV infection have by now been described in various mostly metropolitan areas throughout the world (North America, Brazil, Europe, Australia and Asia) and have been associated with high-risk sexual practices, genital ulcer disease and recreational drug use including parenteral administration (1). The paper by Salazar- Vizcaya and colleagues introduces an interesting modelling approach how changes in behavioral interventions as well as change in uptake and efficacy of DAA based acute HCV therapy could potentially impact the prevalence of acute HCV in the Swiss HIV cohort (2). Clearly, this paper underlines the importance of behavioral interventions as the most effective intervention to decrease acute HCV prevalence. Two major caveats however, need to be formulated in this context. First of all HCV transmission risk factors are rapidly changing as intravenous use of amphetamines is becoming much more common. Professional experts in the field who can help patients with crystal meth dependency however, are scarce and good interventional tools still need to be developed. Secondly, the use of condoms is dramatically declining in patients who are HIV-seropositive but undetectable for HIV-RNA under successful combination antiretroviral therapy as well as in HIV-negative patients who are on PREP. This at least bears the risk of increased rate of transmitting other STDs including acute HCV. The fact that 25% of HIV patients with a first episode of an acute HCV event develop a second infection within the next two years and 50% of those a third acute HCV episode thereafter, underline that behavioral interventions until now are far from being successful (3). Although shortened DAA combination therapy appears promising for treating acute HCV these drugs so far are not licensed and reimbursed for treatment of acute HCV (4). The strongly diminished acceptance of treating acute HCV with an interferon-based approach further increases the pool of untreated patients fueling the epidemic (4). Finally, although not yet observed in Switzerland recent reports of increasing acute HCV infections in HIV-negative MSM underline that there will also be needs for behavioral interventions in HIV-negative at risk populations (5). Getting a well-tolerated DAA combination approved for treatment of acute HCV will remain instrumental to further decrease HCV prevalence among MSM. »

Pr Jürgen Rockstroh, University of Bonn

1. Hullegie SJ, et al. Current knowledge and future perspectives on acute hepatitis C infection. Clin Microbiol Infect. 2015;21(8):797
2. Salazar-Vizcaya L, et al. Hepatitis C virus transmission among HIV-infected men who have sex with men: Modeling the effect of behavioral and treatment interventions. Hepatology 2016
3. Ingiliz P, et al. HCV reinfection incidence and spontaneous clearance rates in HIV-positive men who have sex with men in Western Europe. J Hepatol 2016 [Epub ahead of print]
4. Boesecke C, Rockstroh JK. How will we manage acute HCV in men having sex with men in the era of all oral therapy? J Viral Hepat. 2015;22(1):2-7
5. McFaul K, et al. Acute hepatitis C infection in HIV-negative men who have sex with men. J Viral Hepat. 2015;22:535-8 .