Management of hepatitis C virus infection among people who inject drugs: Treatment uptake, reinfection and risk behaviours

Abstract

The burden of hepatitis C virus (HCV) related liver disease among people who inject drugs (PWID) is increasing. Current highly efficient, simple, and tolerable directacting antiviral (DAA) HCV treatment provides new opportunities to reduce disease burden and transmission among PWID. The World Health Organization therefore targets HCV elimination within 2030. The aim of this thesis was to describe key aspects of HCV infection among PWID related to treatment uptake, reinfection incidence and risk behaviours. Through a series of observational studies, the thesis provides contextual and baseline evidence to inform strategies for HCV elimination in Norway. Study I was a registry linkage study showing that treatment uptake among HCVinfected people receiving opioid substitution treatment (OST) was low (14% over 10 years) prior to the availability of DAA therapies in Norway. Treatment uptake was associated with long-term stability in OST and absence of heavy benzodiazepine use. Study II was a clinical follow-up of a cohort successfully treated for HCV infection in a Scandinavian trial 7 years earlier. The incidence of reinfection was 1.7/100 personyears among all PWID and 4.9/100 person-years among those who had injected drugs after treatment. Relapse to drug use was associated with young age and low education level. Study III was an international multi-centre study evaluating changes in risk behaviours during and following HCV treatment. It demonstrated reductions in reported injecting drug use and hazardous alcohol consumption, but no changes in sharing of injecting equipment. Study IV was a review article covering HCV epidemiology and reinfection incidence in high-risk groups for transmission. The findings emphasize the need for increased treatment uptake among PWID combined with strategies to reduce the risk of reinfection among individuals with ongoing risk behaviours. This will require coordinated efforts across different levels of the health-care system.