Risk of primary incident hepatitis C infection following bacterial sexually transmissible infections among gay and bisexual men in Australia from 2016 to 2020.

In Australia, the incidence of hepatitis C virus (HCV) has declined among gay and bisexual men (GBM) with HIV since 2015 and is low among GBM using HIV pre-exposure prophylaxis (PrEP). However, ongoing HCV testing and treatment remains necessary to sustain this. To assess the potential utility of STIs to inform HCV testing among GBM with HIV and GBM using PrEP, we examined the association between bacterial sexually transmissible infection (STI) diagnoses and subsequent primary HCV infection.

Data were from a national network of 46 clinics participating in the Australian Collaboration for Coordinated Enhanced Sentinel Surveillance. GBM included had ≥1 HCV antibody negative test and ≥1 subsequent HCV antibody and/or RNA test. Discrete time survival analysis was used to estimate the association between a positive syphilis, rectal chlamydia, and rectal gonorrhoea diagnosis in the previous two years on a primary HCV diagnosis, defined as a positive HCV antibody or RNA test.

Among 6,529 GBM with HIV, 92 (1.4%) had an incident HCV infection. A prior positive syphilis diagnosis was associated with an incident HCV diagnosis (aHR 1.99, 95%CI:1.11–3.58). Among 13,061 GBM prescribed PrEP, 48 (0.4%) had an incident HCV diagnosis. Prior rectal chlamydia (aHR 2.75, 95%CI:1.42–5.32) and rectal gonorrhoea (aHR 2.54, 95%CI:1.28–5.05) diagnoses were associated with incident HCV.

Diagnoses of bacterial STIs in the past two years was associated with HCV incidence. These findings suggest that STIs might be of utility to inform HCV testing decisions and guidelines for GBM with HIV and GBM using PrEP.