Abstract Body

Background: Since 2000, an epidemic of hepatitis C virus (HCV) has emerged among HIV-infected men who have sex with men (MSM). Among HIV-infected MSM in the Amsterdam Cohort Study (ACS), an increase in HCV incidence was observed between 2000 and 2003. Data collected during bi-annual surveys at the Amsterdam STI clinic, suggest that the HCV epidemic among HIV-infected MSM in Amsterdam has levelled off in recent years. We updated our previous ACS analysis to examine recent changes. Methodology: All MSM with ≥2 study visits in the ACS between 1984 and 2012 were included. HCV antibody tests were performed retrospectively for all participants until 2003. In order to update the HCV status for HIV-infected MSM, linkage with several clinical and laboratory databases took place. If no negative HCV test result was available after 2008, the last visit before 2012 was tested for HCV antibodies. HIV-uninfected MSM were tested at their first 6-monthly ACS visit after STI screening was introduced in 2009. On finding HCV seroconversion, samples from earlier visits were tested to identify the moment of seroconversion. Incidence rates were calculated and time trends were analyzed using Poisson regression. We allowed for smoothly varying trends via restricted cubic splines. Results: Between October 1984 and January 2012, 2,080/2,457 MSM had ≥2 study visits, and they contributed a total follow-up of 17,310 person-years (PYs). Twenty-nine incident HCV infections were documented. All incident cases had been infected with HIV prior to HCV infection. The overall observed HCV incidence (per 1,000 PYs, 95% CI) was 4.5 (3.0-6.5) among HIV-infected MSM and 0.0 (0.0-0.3) among HIV-uninfected MSM. Among HIV-infected MSM, a significant increase in HCV incidence was observed after 2000 (2005 vs 2000: incidence rate ratio, IRR, 3.41, 95% CI 1.58-7.34). After 2005 however, a non-significant decrease in HCV incidence was observed (2010 vs 2005: IRR, 0.94, 95% CI 0.38-2.36). The observed and modeled HCV incidence rates over time are shown in the attached figure. Conclusions: No incident HCV infections were found among HIV-uninfected MSM. Among HIV-infected MSM, HCV incidence rates increased significantly after 2000. However, HCV incidence seems to have levelled off in recent years, in line with recent findings from the Amsterdam STI clinic. The levelling off might be explained by an increase in testing for HCV, improved HCV treatment uptake, risk reduction, or a saturation-effect among MSM at highest risk for HCV infection.