Reinfection and Risk Behaviors After Treatment of Hepatitis C Virus Infection in Persons Receiving Opioid Agonist Therapy

Background: Hepatitis C virus (HCV) reinfection after successful treatment may reduce the benefits of cure among people who inject drugs. Objective: To evaluate the rate of HCV reinfection for 3 years after successful treatment among people receiving opioid agonist therapy (OAT). Design: A 3-year, long-term, extension study of persons enrolled in the CO-STAR (Hepatitis C Patients on Opioid Substitution Therapy Antiviral Response) study (ClinicalTrials.gov: NCT02105688). Setting: 55 clinical trial sites in 13 countries. Patients: Aged 18 years and older with chronic HCV infection with genotypes 1, 4, or 6 receiving stable OAT. Intervention: No treatments were administered. Measurements: Serum samples were assessed for HCV reinfection. Urine drug screening was performed. Results: Among 296 participants who received treatment, 286 were evaluable for reinfection and 199 were enrolled in the long-term extension study. The rate of HCV reinfection was 1.7 [95% CI, 0.8 to 3.0] per 100 person-years; 604 person-years of follow-up). A higher rate of reinfection was seen among people with recent injecting drug use (1.9 [95% CI, 0.5 to 4.8] per 100 person-years; 212 person-years). Ongoing drug use and injecting drug use were reported by 59% and 21% of participants, respectively, at the 6-month follow-up visit and remained stable during 3 years of follow-up. Limitations: Participants were required to be 80% adherent to OAT at baseline and may represent a population with higher stability and lower risk for HCV reinfection. Rate of reinfection may be underestimated because all participants did not continue in the long-term extension study; whether participants who discontinued were at higher risk for reinfection is unknown. Conclusion: Reinfection with HCV was low but was highest in the first 24 weeks after treatment completion and among people with ongoing injecting drug use and needle–syringe sharing. Primary Funding Source: Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc.