Factors associated with uptake, adherence, and efficacy of hepatitis C treatment in people who inject drugs: a literature review

Viktor Mravčík,^1,2 Lisa Strada,³ Josef Štolfa,^4,5 Vladimir Bencko,⁶ Teodora Groshkova,⁷ Jens Reimer,³ Bernd Schulte<sup>3

1</sup>National Monitoring Centre for Drugs and Drug Addiction, ²Department of Addictology, First Faculty of Medicine, Charles University in Prague, Prague, Czech Republic; ³Centre for Interdisciplinary Addiction Research, University of Hamburg, Hamburg, Germany; ⁴Department of General Practice, Institute for Postgraduate Medical Education in Prague, ⁵Department of General Practice, Second Faculty of Medicine, ⁶Institute of Hygiene and Epidemiology, First Faculty of Medicine, Charles University in Prague, Prague, Czech Republic; ⁷European Monitoring Centre for Drugs and Drug Addiction, Lisbon, Portugal

Introduction and methods: Hepatitis C virus (HCV) infections are highly prevalent amongst people who inject drugs (PWID). Despite well documented evidence of its effectiveness, suggested cost-effectiveness, and potential to reduce HCV prevalence rates, the uptake of antiviral HCV treatment by PWID is low. This nonsystematic literature review describes factors associated with the uptake, adherence, and efficacy of HCV treatment among PWID and discusses strategies to increase their uptake of treatment.
Results: Low HCV treatment uptake among PWID is associated with a number of patient-related and provider-related barriers. Beliefs and fears about low efficacy and adverse effects on the patient’s part are common. A substantial number of factors are associated with the chaotic lifestyle and altered social functioning of PWID, which are often associated with decompensation or relapsing into drug addiction. This may lead to perceived low adherence with treatment and low efficacy on the provider’s part too, where lack of support, inadequate management of addiction, and other drug-related problems and poor treatment of side effects have been described. Practical issues such as the accessibility of treatment and finances also play a role. Strategies to improve the HCV treatment rate among PWID involve pretreatment management and assessment, a multidisciplinary approach, management of side effects, and enhanced education and counseling.
Conclusion: Specific factors are associated with poorer treatment outcomes in PWID on the side of both the patient and the treatment system. However, given that PWID can achieve treatment adherence and sustained virologic response rates comparable with those in nondrug users, drug use per se should not be considered a criterion for exclusion from treatment. Further development of measures leading to higher uptake of treatment and adherence in PWID and appropriate adaptation of HCV treatment guidelines represent important tools in this regard.

Keywords: hepatitis C virus, people who inject drugs, treatment uptake, adherence, efficacy