Given recent treatment advances for and HIV-related implications of hepatitis C virus (HCV) infection, we sought to identify factors associated with past/current and incident HCV infection within a prospective cohort of gay, bisexual, and other men who have sex with men (MSM) in Metro Vancouver, Canada.
Eligible participants were recruited from 2012-2015 using respondent-driven sampling, were aged ≥16 years of age and reported recent sex with another man. Participants completed study visits every 6 months that included a computer-assisted self-interview on demographics, sexual and substance use behaviors, and a nurse-administered clinical questionnaire. A rapid HIV test was administered and a venous blood sample was taken for HCV-antibody serology. We used logistic regression and generalized estimating equations to identify factors associated with prevalent HCV antibodies at enrolment and incident HCV infection at follow-up, respectively. Relative risks (RR) and 95% confidence intervals (CI) are shown. RDS-adjusted population parameters are provided for baseline data.
Of 774 participants, 2.0% (15/551) of HIV-negative and 28.3% (50/223) of HIV-positive MSM were HCV seropositive at enrollment. Of these, 56/65 (86.2%) were aware of their diagnosis, but only 5 HIV-negative and 17 HIV-positive MSM reported prior HCV treatment, with only 2 and 7 of those reporting treatment success. Factors associated with HCV seropositive at enrolment, stratified by HIV status are shown in Table 1. Of 534 participants with follow-up data, we observed 5 HCV-seroconversions for a calculated incidence rate of 0.50 per 100 person-years (95% CI: 0.21-1.21). All incident HCV infections were among single, HIV-positive, gay-identified MSM who did not work as escorts and had never been treated for HCV. Incident HCV infections were associated with older age (RR=1.06, 95% CI: 1.01-1.12), recent crystal methamphetamine use (RR=10.62, 95% CI: 1.77-63.64), and a greater number of recent anal sex partners (RR=1.01, 95% CI: 1.01-1.02). Notably, only 1 of 5 with HCV seroincidence reported recent injection drug use, and as such was not associated with HCV seroincidence (RR=3.01, 95% CI: 0.35–26.15, p=0.32).
New cases of HCV infection indicate a potential shift to sexual transmission among HIV-positive gay men based on the lack of association with recent injecting behavior. Crystal methamphetamine use remains a strong factor associated with HCV seropositivity and predictor of new infection.