Hepatitis C Virus Infections in the Swiss HIV Cohort Study: A Rapidly Evolving Epidemic

Background. Hepatitis C virus (HCV) infection has a growing impact on morbidity and mortality in patients infected with human immunodeficiency virus (HIV). We assessed trends in HCV incidence in the different HIV transmission groups in the Swiss HIV Cohort Study (SHCS). Methods. HCV infection incidence was assessed from 1998, when routine serial HCV screening was intro-duced in the SHCS, until 2011. All HCV-seronegative patients with at least 1 follow-up serology were included. Incidence rates (IRs) of HCV infections were compared between men who have sex with men (MSM), injection drug users (IDU), and heterosexuals (HET). Results. HCV incidence was assessed in 3333 MSM, 123 IDU, and 3078 HET with a negative HCV serology at baseline. Over 23 707 person-years (py) for MSM, 733 py for IDU, and 20 752 py for HET, 101 (3%), 41 (33%), and 25 (1%) of patients seroconverted, respectively. The IR of HCV infections in MSM increased from 0.23 (95% credible interval [CrI],.08–.54) per 100 py in 1998 to 4.09 (95 % CrI, 2.57–6.18) in 2011. The IR decreased in IDU and remained <1 per 100 py in HET. In MSM, history of inconsistent condom use (adjusted hazard ratio [HR], 2.09; 95 % CI, 1.33–3.29) and past syphilis (adjusted HR, 2.11; 95 % confidence interval [CI], 1.39–3.20) predicted HCV seroconversion. Conclusions. In the SHCS, HCV infection incidence decreased in IDU, remained stable in HET, and increase