Adherence to Once-daily and Twice-daily Direct-acting Antiviral Therapy for Hepatitis C Infection Among People With Recent Injection Drug Use or Current Opioid Agonist Therapy

Clin Infect Dis. 2020 Oct 23;71(7):e115-e124. doi: 10.1093/cid/ciz1089.


Background: This study investigated adherence and associated factors among people with recent injection drug use (IDU) or current opioid agonist therapy (OAT) and compared once-daily to twice-daily hepatitis C virus (HCV) direct-acting antiviral (DAA) therapy.

Methods: SIMPLIFY and D3FEAT are international, multicenter studies that recruited participants with recent IDU (previous 6 months; SIMPLIFY, D3FEAT) or current OAT (D3FEAT) between March 2016 and February 2017 in 8 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 nonadherence (<90% adherent) between dosing patterns.

Results: Of 190 participants, 184 (97%) completed treatment. Median adherence was 92%, with higher adherence among those receiving once-daily vs twice-daily therapy (94% vs 87%, P = .005). Overall, 40% of participants (n = 76) were nonadherent (<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 twice-daily dosing (OR, 2.81 [95% CI, 1.47-5.36]) were associated with nonadherence. Adherence decreased during therapy. Sustained virologic response was high in nonadherent (89%) and adherent populations (95%, P = .174), with no difference in SVR between those who did and did not miss 7 consecutive doses (92% vs 93%, P = .897).

Conclusions: This study demonstrated high adherence to once- and twice-daily DAA therapy among people with recent IDU or currently receiving OAT. Nonadherence described did not impact treatment outcomes, suggesting forgiveness to nonadherence.

Keywords: HCV; OAT; PWID; injection drug users; treatment.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Analgesics, Opioid / therapeutic use
  • Anilides / therapeutic use
  • Antiviral Agents / therapeutic use
  • Drug Therapy, Combination
  • Hepacivirus
  • Hepatitis C* / drug therapy
  • Hepatitis C, Chronic* / drug therapy
  • Humans
  • Pharmaceutical Preparations*
  • Ribavirin / therapeutic use
  • Sustained Virologic Response


  • Analgesics, Opioid
  • Anilides
  • Antiviral Agents
  • Pharmaceutical Preparations
  • Ribavirin