Theme: Clinical Research Year: 2019
Background: Treatment adherence has been a concern regarding the scale-up of
HCV DAA therapy in people who inject drugs. This study investigated treatment
adherence and associated factors among people with recent injecting drug use or
current opioid substitution therapy (OST) and compared once-daily to twice-daily
DAA therapy.
Methods: SIMPLIFY and D3FEAT are international, open-label, single-arm,
multicentre studies which recruited participants with recent injecting drug use
(previous six months; SIMPLIFY, D3FEAT) or current OST (D3FEAT) between
March 2016 and February 2017 in eight countries (25 sites). Participants received
sofosbuvir/velpatasvir (once-daily; SIMPLIFY) or paritaprevir/ritonavir, ombitasvir,
dasabuvir (twice-daily; D3FEAT) ±ribavirin for 12 weeks administered in one-week
electronic blister-packs which recorded the time and date of each dose. We
evaluated percent adherence (doses taken divided by doses expected) and nonadherence (<90% adherent) using logistic regression and generalised estimating
equations with comparisons of adherence between the dosing patterns.
Results: Among 190 participants (once-daily n=103, twice-daily n=87), 97% in both
groups completed treatment with a median adherence of 92%, which was higher
among the once-daily population (94% vs 87%, p=0.005). Overall, 40% of
participants (n=76) were considered non-adherent with recent stimulant injecting
(odds ratio [OR] 2.48, 95% confidence interval [CI] 1.28-4.82) and unstable housing
(OR 2.18, 95% CI 1.01-4.70) associated with non-adherence. Participants receiving
twice-daily dosing were more likely to be non-adherent (OR 2.81, 95% CI 1.47-5.36).
Adherence significantly decreased over the course of therapy in both the once-
(P<0.001) and twice-daily (P<0.001) groups. Despite non-adherence, SVR was high
with once-daily (94%) and twice-daily (91%) therapy. SVR was lower but not
significant in the non-adherent population (89% vs. 95%, P=0.174).
Conclusion: This study demonstrated lower adherence among participants
receiving twice-daily dosing compared to once-daily suggesting that pill burden may
negatively impact patient adherence. Treatment response remained high,
demonstrating that DAA therapy has some “forgiveness” to non-adherence.
Disclosure of Interest Statement:
The authors recognise the considerable contribution that industry partners make to
professional and research activities. We also recognise the need for transparency of
disclosure of potential conflicts of interest by acknowledging these relationships in
publications and presentations