Treatment for hepatitis C virus infection among people who inject drugs attending opioid substitution treatment and community health clinics: the ETHOS Study.

AIMS: To estimate adherence and response to therapy for chronic hepatitis C virus (HCV) infection among people with a history of injecting drug use. A secondary aim was to identify predictors of HCV treatment response. DESIGN: Prospective cohort recruited between 2009 and 2012. Participants were treated with peg-interferon alfa-2a/ribavirin for 24 (genotypes 2/3, G2/3) or 48 weeks (genotype 1, G1). SETTING: Six opioid substitution treatment (OST) clinics, two community health centres and one Aboriginal community-controlled health organization providing drug treatment services in New South Wales, Australia. PARTICIPANTS: Among 415 people with a history of injecting drug use and chronic HCV assessed by a nurse, 101 were assessed for treatment outcomes (21% female). MEASUREMENTS: Study outcomes were treatment adherence and sustained virological response (SVR, undetectable HCV RNA >24 weeks post-treatment). FINDINGS: Among 101 treated, 37% (n = 37) had recently injected drugs (past 6 months) and 62% (n = 63) were receiving OST. Adherence ≥ 80% was 86% (n = 87). SVR was 74% (75 of 101), with no difference observed by sex (males: 76%, females: 67%, P = 0.662). In adjusted analysis, age < 35 (versus ≥ 45 years) [adjusted odds ratio (aOR) = 5.06, 95% confidence interval (CI) = 1.47, 17.40] and on-treatment adherence ≥ 80% independently predicted SVR (aOR = 19.41, 95% CI = 3.61, 104.26]. Recent injecting drug use at baseline was not associated with SVR. CONCLUSIONS: People with a history of injecting drug use and chronic hepatitis C virus attending opioid substitution treatment and community health clinics can achieve adherence and responses to interferon-based therapy similar to other populations, despite injecting drugs at baseline. Younger age and adherence are predictive of improved response to hepatitis C virus therapy.