Hepatitis C virus infection in HIV-infected men in Singapore, 2006-2018: incidence and associated factors.

Background The epidemiology of hepatitis C virus (HCV) infection in people living with HIV has been evolving, with increasing evidence of permucosal (sexual) transmission identified predominantly in HIV-positive men who have sex with men (MSM). The aim of this study was to estimate the incidence rate and elucidate epidemiological factors associated with HCV infection among HIV-infected men in Singapore from 2006 to 2018. Methods: A retrospective cohort study was conducted using a clinical database maintained by the Clinical HIV Program at the National Centre for Infectious Diseases, Singapore. Factors associated with incident HCV infections were identified using Cox proportional hazards regression analyses. Results: Among 1348 HIV-infected male patients who were HCV seronegative at baseline, 64 (4.7%) subsequently tested positive for HCV, giving an incidence of 0.88 per 100 person-years of follow-up (PYFU) (95% confidence interval (CI) 0.69–1.13). The incidence rate of HCV seroconversion increased from 0.33 (95% CI 0.12–0.71) per 100 PYFU in 2010–2012 to 1.93 (95% CI 1.36–2.67) in 2016–2018. Independent factors associated with incident HCV infection were younger age groups at HIV diagnosis versus ≥45 years, HIV acquisition via MSM or via both sexual contact and intravenous drug use versus heterosexual transmission, HIV diagnosis in later periods versus 2006–2009, and recent syphilis acquisition. Conclusions: An increasing trend of incident HCV infection was seen in HIV-infected men, particularly for MSM. Preventive and behavioural interventions should be targeted at HIV-infected individuals engaged in high-risk sexual behaviour.