Incidence and risk factors for incident Hepatitis C infection among men who have sex with men with HIV-1 infection in a large Urban HIV clinic in Tokyo.

Background: The epidemiology of hepatitis C virus (HCV) infection among HIV-infected men who have sex with men (MSM) who do not inject drugs in Asia remains unknown. Method: The incidence and risk factors for incident HCV infection among HIV-infected MSM at a large HIV clinic in Tokyo were elucidated. Poisson regression compared the incidence of HCV seroconversion at different observation periods. Results: Of 753 HIV-1 infected MSM patients negative for HCV antibody (HCVAb) at baseline and available follow-up HCVAb test, 21 patients (2.8%) seroconverted to HCVAb positive over 2246 person-years (PY), for an incidence of 9.35 per 1000 PY. The incidence increased over time from 0 per 1000 PY in 2005-2006, 3.0 per 1000 PY in 2007-2008, 7.7 per 1000 PY in 2009-2010, to 24.9 per 1000 PY in 2011-2012 (P = 0.012). Of 21 incident cases, only 4 (19%) were injection drug users, and sensitivity analysis that excluded injection drug users yielded similar findings. Multivariate analysis identified illicit drug use to be an independent risk for HCV infection (hazard ratio = 3.006; 95% confidence interval: 1.092 to 8.275; P = 0.033). Conclusions: Incident HCV infection is increasing among HIV-1-infected MSM noninjection drug users at resource-rich setting in Asia. Illicit drug use is an independent risk factor for incident HCV infection in this population.