Chronic hepatitis C virus (HCV) infection remains a health burden in people living with human immunodeficiency virus (HIV). Interferon (IFN)-based therapy is the treatment of choice for HCV infection for HIV coinfected patients in earlier years. However, the treatment responses are far from ideal and the treatment-emergent adverse events (AEs) are frequently encountered. Based on the excellent efficacy and safety, IFN-free direct acting antivirals (DAAs) have been the mainstay of therapy for HCV. Furthermore, the world health organization (WHO) has set the goal of global HCV elimination by 2030. The microelimination of HCV among HIV/HCV-coinfected patients is also listed as the prioritized target by WHO. Although the overall treatment response has improved dramatically during the past 5-10 years, several studies have indicated the HIV/HCV-coinfected patients had high risks of reinfection following successful antiviral treatment. The risk of HCV reinfection was reported to be 24.6% among HIV-positive men who have sex with men (MSM) in Austria, German, France and the United Kingdom who attained sustained virologic response (SVR) by IFN-based therapy. Two recent studies from Canada showed that the incidence of HCV reinfection in HIV-positive patients was higher that HIV-negative patients (3.44 vs. 1.13 per 100 person-year; 2.56 vs. 1.12 per 100 person-year). In Taiwan, 14.1% of the HIV-positive patients had HCV reinfection following treatment-induced or spontaneous viral clearance, resulting an incidence of 8.2 per 100 person-year with a total of 218.3 person-years of follow-up for these patients.

Because data regarding to the HCV reinfection in HIV-positive patients are still limited, where a more comprehensive assessment of HCV reinfection is important based on the perspectives of HCV microelimination among HIV-positive patients in Taiwan, the investigators thus aim to conduct a long-term, large-scale cohort study to assess the risk of HCV reinfection in HIV-positive patients achieving SVR after IFN-based or IFN-free therapies, and to assess the factors associated with different risks of reinfection in these patients.

Chronic hepatitis C virus (HCV) infection remains a health burden in people living with human immunodeficiency virus (HIV). Compared to the midpoint prevalence rate of HCV coinfection to be 2.4% in the general HIV-positive population, the prevalence rates are higher among bisexual men (4.0%), gay men (6.4%), and people who inject drugs (PWIDs) (82.4%). Following the widespread use of antiretroviral therapy (ART) for HIV which improves the health outcome by reducing the acquired immunodeficiency syndrome (AIDS)-related deaths, the liver-related death has become a frequent cause of non-AIDS-related deaths in HIV-positive population. If HCV is left untreated, the HIV/HCV-coinfected patients may have higher risks of developing hepatic decompensation or hepatocellular carcinoma (HCC) than HCV-monoinfected patients due to the accelerated progression of hepatic fibrosis.

Interferon (IFN)-based therapy is the treatment of choice for HCV infection for HIV coinfected patients in earlier years. However, the treatment responses are far from ideal and the treatment-emergent adverse events (AEs) are frequently encountered. Based on the excellent efficacy and safety, IFN-free direct acting antivirals (DAAs) have been the mainstay of therapy for HCV. Furthermore, the world health organization (WHO) has set the goal of global HCV elimination by 2030. The microelimination of HCV among HIV/HCV-coinfected patients is also listed as the prioritized target by WHO.

Although the overall treatment response has improved dramatically during the past 5-10 years, several studies have indicated the HIV/HCV-coinfected patients had high risks of reinfection following successful antiviral treatment. The risk of HCV reinfection was reported to be 24.6% among HIV-positive men who have sex with men (MSM) in Austria, German, France and the United Kingdom who attained sustained virologic response (SVR) by IFN-based therapy. Two recent studies from Canada showed that the incidence of HCV reinfection in HIV-positive patients was higher that HIV-negative patients (3.44 vs. 1.13 per 100 person-year; 2.56 vs. 1.12 per 100 person-year). In Taiwan, 14.1% of the HIV-positive patients had HCV reinfection following treatment-induced or spontaneous viral clearance, resulting an incidence of 8.2 per 100 person-year with a total of 218.3 person-years of follow-up for these patients.

Because data regarding to the HCV reinfection in HIV-positive patients are still limited, where a more comprehensive assessment of HCV reinfection is important based on the perspectives of HCV microelimination among HIV-positive patients in Taiwan, the investigators thus aim to conduct a long-term, large-scale cohort study to assess the risk of HCV reinfection in HIV-positive patients achieving SVR after IFN-based or IFN-free therapies, and to assess the factors associated with different risks of reinfection in these patients.

Inclusion Criteria:

• Age old than 20 years old
• Patients with human immunodeficiency virus coinfection (HIV) during IFN-based or IFN-free antiviral therapy for hepatitis C virus (HCV) infection
• Patients achieving SVR, defined as undetectable serum HCV RNA at week 12 off-therapy

Exclusion Criteria:

• Poor access to sites for venipuncture

HIV/HCV-coinfected patients who undergo antiviral therapy for hepatitis C virus infection and who achieve sustained virologic response