Hepatitis C Virus Seroprevalence, Incidence, and Screening Patterns in Ontario Preexposure Prophylaxis Users.

Background: Hepatitis C virus (HCV) has emerged as a sexually transmitted infection in gay, bisexual, and other men who have sex with men (GBM). We estimated the seroprevalence and incidence of HCV infection and examined patterns of HCV testing among GBM using human immunodeficiency virus preexposure prophylaxis (PrEP) in Ontario, Canada. Methods: We analyzed data from the Ontario PrEP Cohort Study (ON-PrEP), a prospective cohort of PrEP users from 10 Ontario clinics. Participants completed an online questionnaire and study staff collected clinical information into a study database biannually for 2 years. We estimated the baseline seroprevalence and incidence of HCV infection and examined patterns of HCV testing during follow-up. We further explored differences in sociodemographic/clinical variables between those with and without prevalent/incident HCV infection through bivariate analysis. Results: Among 557 eligible PrEP users, 382 (68.6%) underwent baseline HCV antibody testing, of whom 5 tested HCV seropositive, giving a seroprevalence of 1.3% (95% confidence interval [CI], .43%-3.03%). Only 245 (43.9%) participants underwent HCV antibody testing after baseline, and median time to participants' first follow-up test was 245 days. During follow-up, 2 participants tested newly HCV seropositive, giving an incidence of 0.47/100 person-years (95% CI, .06-1.69) over 428.9 years of follow-up. Participants with prevalent/incident HCV infection during the study appeared more likely to report giving money, drugs, gifts, or services for sex in the 3 months preceding enrollment compared to those who never tested HCV seropositive ( Conclusions: HCV seroprevalence and incidence were low but not negligible among Ontario PrEP users. HCV antibody and RNA testing were suboptimal.