High incidence of HCV in HIV-negative men who have sex with men using pre-exposure prophylaxis.

ABSTRACT Background and Aims Hepatitis C virus (HCV) has emerged as a sexually transmitted infection (STI) among HIV-positive men who have sex with men (MSM). We evaluated HCV-incidence and its risk-factors among HIV-negative MSM using HIV pre-exposure prophylaxis (PrEP). Methods Participants of the Amsterdam PrEP project were tested for HCV antibodies or HCV-RNA every 6 months. Participants used daily or event-driven PrEP and could switch regimens during follow-up. We calculated incidence rates (IRs) for overall HCV-infection and separately for primary and re-infection. A univariable Bayesian exponential survival model was used to identify risk-factors associated with incident HCV-infection. The HCV NS5B gene fragment (709 bp) was sequenced and compared to HCV isolates from HIV-positive MSM and other risk groups (n=419) using phylogenetic analysis. Results Among 350 participants contributing 653.6 person-years (PY), we detected 15 HCV infections in 14 participants (IR=2.30/100PY). There were eight primary infections (IR=1.27/100PY) and seven re-infections (IR=27.8/100PY). IR was 2.71/100PY in daily and 1.15/100PY in event-driven PrEP-users. Factors associated with incident HCV-infection were higher number of receptive condomless anal sex acts with casual partners (posterior Hazards Rate (HR)=1.57 per ln increase, 95% Credibility Interval (CrI)=1.09-2.20), anal STI (posterior HR=2.93, 95%CrI=1.24-7.13), injecting drug use (posterior HR=4.69, 95%CrI=1.61-12.09) and sharing straws when snorting drugs (posterior HR=2.62, 95%CrI=1.09-6.02). We identified robust MSM-specific HCV clusters of subtypes 1a, 4d, 2b and 3a, which included MSM with and without HIV. Conclusions HIV-negative MSM on PrEP are at risk for incident HCV-infection, while identified risk-factors are similar to those in HIV-positive MSM. Regular HCV-testing is needed, especially for those with a previous HCV-infection and those reporting risk-factors.