Reinfection with hepatitis C after direct-acting antiviral (DAA) therapy is highest in people with recent injection drug use, according to a recent study published in the Journal of Hepatology. However, among people who inject drugs, daily use of opioid-agonist therapy was associated with a lower risk of reinfection.
“Direct-acting antiviral therapies are an important tool for hepatitis C virus (HCV) elimination,” wrote authors led by Carmine Rossi, PhD, British Columbia Center for Disease Control, Vancouver, BC, Canada. “However, reinfection among people who inject drugs (PWID) may hamper elimination targets.”
HCV infection does not result in lifelong immunity, and individuals who are cured of the infection with DAA therapies but continue to engage in risky behaviors can become reinfected. Such reinfection is a public health concern and can affect efforts to control transmission of the disease, as well as clinician decision-making. Little data exist on the frequency of HCV reinfection following DAA therapy, prompting this large population-level study.
“The objective of the current study was to assess HCV reinfection rates in a population-based cohort of HCV-infected individuals who initiated all-oral DAA therapy in British Columbia, Canada, with an emphasis on those identified as PWID,” the authors wrote.
For this study, researchers mined the British Columbia Hepatitis Testers Cohort, which included about 1.7 million individuals screened for HCV, and analyzed data from 4,114 eligible individuals (65% of whom were men and 83% were born before 1965) who attained sustained virologic response (SVR) secondary to treatment with oral, interferon-free DAA therapies and had one or more subsequent HCV RNA measurements after attaining SVR.
The researchers identified reinfection with HCV by means of a positive RNA measurement following SVR. They used a validated algorithm to identify and then classify PWID by either recent (< 3 years before SVR) or former (≥ 3 years before SVR) injection drug use.
The researchers analyzed the association between the risk of HCV reinfection and factors including: age of treatment, initiation, birth cohort, sex, year of HCV diagnosis, HIV co-infection, injection drug use, opioid-agonist therapy, problematic alcohol intake, and major mental health disorders. Findings showed that major mental illness, problematic alcohol use, or HIV co-infection were not associated with HCV reinfection following SVR.
Of those individuals eligible for data analysis, 21% (875) were recent PWID and 44% (1,793) were former PWID. Opioid-agonist therapy was documented in 19% of PWID, and there were 40 reinfections for 2,767 person-years (PYs). Reinfection rates were higher in recent PWID (3.1/100 PYs) and former PWID (1.4/100 PYs) compared with non-PWID (0.3/100 PYs).
Results showed that, in recent PWID, HCV reinfection rates were highest in those born after 1975 and those with HIV co-infection. Patients who were continuously taking opioid-agonist therapy after DAA therapy exhibited a lower reinfection rate. This finding indicated that, among PWID, daily opioid-agonist therapy may reduce the risk of HCV reinfection.
The investigators noted that there were some limitations to this study. For instance, they were not able to differentiate late relapse from true reinfection, which would require sensitive sequencing methods and phylogenetic analysis data. Additionally, SVR follow-up after DAA treatment was limited; thus, it remains to be fully elucidated how reinfection rates change over time.
Nevertheless, the authors maintained that findings from this study may have important implications for the management of individuals with HCV. “These results highlight the need for engaging PWID with ongoing risk in harm-reduction and prevention services following treatment to reduce reinfection risk and to achieve World Health Organization (WHO) HCV elimination goals,” the authors concluded.
This study was supported by the British Columbia Centre for Disease Control and the Canadian Institutes of Health Research.