OBJECTIVE: To better understand risk factors for the sexual transmission of hepatitis C viral (HCV) infection among men who have sex with men (MSM).

DESIGN: Case-control study among HIV-infected MSM, attending AIDS Reference Centers in Belgium.

METHODS: Cases were HIV-infected MSM who were diagnosed with HCV between January 2010 and December 2013. For each case, 2 controls were randomly selected among the HIV-positive MSM who tested negative for HCV around the same time as the cases were identified. Consenting participants were interviewed with a questionnaire on risk factors. Medical records were abstracted to document past episodes of sexually transmitted infections (STIs). Associations between HCV infection and risk factors were explored using bivariate analysis followed by multiple logistic regression analysis.

RESULTS: A total of 52 cases and 90 controls were recruited. In multivariate analysis, douching before anal intercourse [adjusted odds ratio (AOR) = 9.84, 95% CI: 2.26 to 42.78], fisting (AOR = 3.54, 95% CI: 1.31 to 9.57), having intercourse with HIV-positive men (AOR = 5.51, 95% CI: 1.87 to 16.20), and a documented gonorrhoea or chlamydial infection in the year before inclusion in the study (AOR = 4.50, 95% CI: 1.11 to 18.31) were independently associated with incident HCV infection.

CONCLUSIONS: Our study confirmed fisting and suffering from other STIs as risk factors for HCV and suggested an increased risk of HCV associated with serosorting. Furthermore, we identified anal douching as being associated with HCV infection. The role that douching plays in the acquisition of HCV infection and other STIs requires further research, as well as the effect of serosorting on STI transmission.