Reinfection following successful direct-acting antiviral therapy for hepatitis C virus infection among people with recent injecting drug use: the SHARP-C study.

BACKGROUND

Injecting drug use following treatment for hepatitis C virus (HCV) may result in reinfection, potentially reversing individual, and population benefits of HCV treatment. The aim of this study was to evaluate the incidence of HCV reinfection following successful direct acting antiviral (DAA) therapy among people with recent injecting drug use.

METHODS

This analysis used data from an observational cohort study of people with recent injecting drug use (previous six months) following successful DAA treatment in Australia, Canada, and New Zealand. Participants were either recruited prior to commencing DAA therapy or after a documented sustained virological response (SVR). Participants were assessed three-monthly for HCV reinfection. Reinfection was defined as recurrence of virus distinct from the initial infecting strain or recurrence after confirmed cure at or after 12 weeks post-treatment. Person-time of observation and Cox proportional hazard models were used to calculate reinfection incidence and associated factors.

RESULTS

Among 112 participants who contributed follow-up time at risk of reinfection (113 person-years of follow-up time), the median age was 43 years, 34 % were female, and 86 % reported injecting drug use in the month prior to enrolment. Eleven cases of reinfection were observed for an incidence of 9.7/100 person-years (95 % confidence interval [CI], 5.4-17.4) overall, 11.1/100 person-years (95 % CI, 6.1-20.0) among people who reported injecting drugs during follow-up, and 24.3/100 person-years (95 % CI, 7.8-75.3) among those who reported sharing needles/syringes during follow-up. All cases of HCV reinfection occurred among people reporting injecting drug use during the study.

CONCLUSIONS

The relatively high incidence of reinfection seen in this study underscores the importance of targeted harm reduction measures and monitoring for HCV reinfections within the first year following successful treatment among people who inject drugs. Additional research into integrated models of care incorporating harm reduction and supporting reducing risk of reinfection and HCV treatment are needed.