International reports of a hepatitis C virus (HCV) epidemic among HIV-infected men who have sex with men (HIV+ MSM) associated with recreational drug use and with sex are causing concern. However, little is known about the HCV epidemic among MSM in San Diego. We assess HCV incidence among HIV+ MSM in San Diego in relation to injecting drug and methamphetamine use.
We performed a retrospective cohort analysis of HCV incidence among HIV+ MSM attending the largest HIV clinic in San Diego (UCSD Owen Clinic) from 2000-2015. Incident HCV infection was assessed among HIV+ MSM with a baseline negative anti-HCV test between 2000 and 2015, and defined as any new positive anti-HCV or HCV-RNA test after the start of follow-up. Group risks were defined as individuals who reported ever injecting drug use (IDU) or using methamphetamine.
A total of 2,396 MSM, who were initially HCV uninfected and had at least 1 further test during a median of 5.5 years of follow-up (IQR 2.8-9.2), were included in the incidence analysis. Overall, 149 HCV seroconversions occurred over 12,560 person-years of follow-up (incidence rate = 1.19/100py, [95%CI 1.01-1.39]), which increased over time (p=0.027, Fig.1A). Individuals were tested a median 3 times (interquartile range[IQR] 2-4) with a median testing interval of 1.2 years (IQR 0.6-2.2). Incident cases were identified on average of 10.6 years (IQR: 5.7-17.5) from HIV diagnosis and 3.6 years (IQR 1.5-6.4) from the first HCV negative test. Among individuals who seroconverted for HCV, 13.4% (20/149) denied IDU and methamphetamine use. HCV incidence was significantly higher among HIV+ MSM reporting IDU compared to those not reporting IDU (2.6/100py vs 0.97/100py, p<0.001), with no evidence of an increasing trend over time (Fig.1B). HCV incidence was also significantly higher among HIV+ MSM reporting ever using meth compared to those denying meth use (1.53/100py vs 0.52/100py, p<0.001) with a significant increase of HCV incidence over time (p<.001, Fig.1C).
These findings suggest that HCV incidence is increasing among HIV+ MSM in San Diego. These rates are similar to London and other major European cities, and double that observed in the US Multicenter AIDS Cohort Study. This study also documented incident HCV infection among HIV+ MSM who do not inject drugs and an increased HCV incidence among individuals reporting meth use. Further work is needed to explain this trend and identify prevention strategies required to control the epidemic.