Abstract Body

Hepatitis C Virus (HCV) and HIV infections co-occur in certain population groups because of shared risk factors. Limited data on time to HIV infection among HCV infected individuals is available. Understanding differences in HIV incidence among these individuals can help inform strategies to prevent HIV infection. We estimated the time to HIV diagnosis among HCV infected individuals and evaluated factors that could affect HIV infection risk.

The British Columbia Hepatitis Testers Cohort (BC-HTC) includes all BC residents (~1.5 million) tested for HCV or HIV from 1990 to 2013 and links medical visits, hospitalizations, cancers, prescriptions and deaths. All HCV positive and HIV negative individuals were followed for a positive HIV test to estimate adjusted hazard ratios (aHR) for factors associated with HIV infection using Cox proportional hazards regression.

Of 36,163 individuals who were HCV positive and HIV negative at cohort entry, 2255 (6.2%) acquired HIV over 266,010 years of follow-up for an overall incidence rate of 8.5/1000PY (person years). The HIV incidence rate among HCV seroconverters was 10.7/1000PY versus 8.2/1000PY among those with prevalent HCV infection at diagnosis. Overall median [IQR] time to HIV infection was 3.36 [4.96] years, shorter for seroconverters than prevalent HCV infections (2.78 vs 3.52, p =0.003). In Cox regression, people who injected drugs (PWID) (aHR: 1.42, 95% CI: 1.29-1.57), those with Hepatitis B Virus (HBV) infection (aHR: 1.37, 95% CI: 1.19-1.58), men who have sex with men (MSM) (aHR: 5.91, 95% CI: 4.21-8.29), and urban residence (aHR: 1.40, 95% CI: 1.19-1.65) were associated with higher risk of HIV infection after adjusting for number of HIV tests. Opioid Substitution Therapy (OST) (aHR: 0.39, 95% CI: 0.33-0.45) and psychiatric counseling (aHR: 0.48, 95% CI: 0.44-0.54) were associated with lower risk of HIV infection.

Injection drug use, HBV coinfection, MSM, and urban residence increased the risk of HIV; while engagement in OST and mental health counseling reduced the risk of HIV infection among HCV infected individuals. *The BC-HTC team: Gesink D, Gilbert M, J Wong, M Kuo, A Yu, Alvarez M, Chong M, H Samji, J Buxton, Roth D, Consolacion T, Murti M, Ogilvie G, Balshaw R, M Tyndall, M Krajden