Hepatitis C Treatment in People Who Inject Drugs: Treatment As Prevention Based on Risk Level

With the focus of hepatitis C virus (HCV) treatment shifting from interferon-based regimens to more effective oral, direct-acting antiviral regimens, more patients are likely to be willing to engage in treatment. However, high medication cost may limit HCV treatment accessibility, particularly among people who inject drugs (PWID). Although treatment of HCV in PWID may decrease viral transmission, re-infection is a concern. Using mathematical modelling, the authors investigated the expected benefits of HCV treatment in high-risk PWID who share injecting equipment versus low-risk PWID who rarely or never share injecting equipment.  Primary outcomes included the probability of becoming and remaining HCV uninfected and the expected number of prevented infections due to decreased HCV transmission. The authors studied the effects of risk behaviors on the prevalence of HCV in exchanged syringes.

• Determining which risk group to target for HCV treatment depended on the prevalence of HCV in the population; when >50% of the syringes in a population of PWID were infected with HCV, targeting HCV treatment at low-risk individuals was most beneficial. However, below this level, it was most beneficial to target HCV in high-risk individuals.
• By sensitivity analysis, the authors noted that a relatively small high-risk group could strongly impact the prevalence of HCV among returned syringes, but not necessarily affect HCV prevalence among PWID.
• Modelling the combination of risk reduction strategies coupled with HCV treatment had the greatest benefit among the high-risk group.

Comments:

The results from this study suggest that directing HCV treatment strategies among PWID based on risk level may enhance the population-level benefits achieved. Further studies conducted in clinical populations of PWID with differing risk profiles will add knowledge to our understanding of both the individual and public health impact of HCV treatment.

Jeanette M. Tetrault, MD

Reference:

de Vos AS, Prins M, Kretzschmar ME. Hepatitis C treatment as prevention among injection drug users: who should we cure first? Addiction. 2015 [Epub ahead of print]. doi:10.1111/add.12842.