Abstract

BACKGROUND: This study investigated treatment adherence and associated factors among people with recent injecting drug use or current opioid agonist therapy (OAT) and compared once-daily to twice-daily DAA therapy. METHODS: SIMPLIFY and D3FEAT are international, multicentre studies which recruited participants with recent injecting drug use (previous six months; SIMPLIFY, D3FEAT) or current OAT (D3FEAT) between March 2016 and February 2017 in eight countries. Participants received sofosbuvir/velpatasvir (once-daily; SIMPLIFY) or paritaprevir/ritonavir/ombitasvir, dasabuvir (twice-daily) +/-ribavirin (D3FEAT) for 12 weeks administered in electronic blister-packs. We evaluated overall adherence (proportion of prescribed doses taken) and non-adherence (<90% adherent) with comparisons between dosing patterns. RESULTS: Of 190 participants who commenced treatment, 184 (97%) completed treatment. Median adherence was 92% with higher adherence among those receiving once-daily vs. twice-daily therapy (94% vs. 87%, P=0.005). Overall, 40% of participants (n=76) were considered non-adherent (<90% adherent). Recent stimulant injecting (odds ratio [OR] 2.48, 95% confidence interval [CI] 1.28-4.82), unstable housing (OR 2.18, 95% CI 1.01-4.70), and receiving twice-daily dosing (OR 2.81, 95% CI 1.47-5.36) were associated with non-adherence. Adherence decreased over the course of therapy SVR was high in non-adherent (89%) and adherent populations (95%, P=0.174) with no difference in SVR between those who did and did not miss at least seven consecutive doses (92% vs 93%, P=0.897). CONCLUSION: This study demonstrated high adherence to once- and twice-daily HCV DAA therapy among people with recent injecting drug use or were currently receiving OAT. The levels of non-adherence described did not impact treatment outcomes, suggesting forgiveness to non-adherence.

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