Adherence to treatment for recently acquired hepatitis C virus (HCV) infection among injecting drug users

Adherence to HCV therapy impacts sustained virological response (SVR) but there are limited data on adherence, particularly among injecting drug users (IDUs). We assessed 80/80 adherence (≥80% of PEG-IFN doses, ≥80% treatment), on-treatment adherence, and treatment completion in a study of treatment of recent HCV infection (ATAHC).

Participants with HCV received pegylated interferon (PEG-IFN) alfa-2a (180microg/week, n=74) and those with HCV/HIV received PEG-IFN alfa-2a with ribavirin (n=35), for a planned 24 weeks. Logistic regression analyses were used to identify predictors of PEG-IFN 80/80 adherence.

A total of 109 out of 163 patients received treatment (HCV, n=74; HCV/HIV, n=35), with 75% ever reporting IDU. The proportion with 80/80 PEG-IFN adherence was 82% (n=89). During treatment, 14% missed ≥1 dose (on-treatment adherence=99%). Completion of 0-4, 5-19, 20-23, and all 24 weeks of PEG-IFN therapy occurred in 10% (n=11), 14% (n=15), 6% (n=7) and 70% (n=76) of cases, respectively. Participants with no tertiary education were less likely to have 80/80 PEG-IFN adherence (AOR 0.29, p=0.045). IDU prior to or during treatment did not impact 80/80 PEG-IFN adherence. SVR was higher among those patients with ≥80/80 PEG-IFN adherence (67% vs. 35%, p=0.007), but similar among those with and without missed doses during therapy (73% vs. 60%, p=0.309). SVR in those patients discontinuing therapy between 0-4, 5-19, 20-23, and 24 weeks was 9%, 33%, 43%, and 76%, respectively (p<0.001).

High adherence to treatment for recent HCV was observed, irrespective of IDU prior to, or during, therapy. Sub-optimal PEG-IFN exposure was mainly driven by early treatment discontinuation rather than missed doses during therapy.