Self-reported and measured adherence to hepatitis C direct-acting antiviral therapy and sustained virologic response among people who inject drugs: The HERO study

Background: Objective adherence measures, such as electronic blister pack (BP), for direct-acting antivirals (DAAs) for hepatitis C virus (HCV) treatment have high accuracy, but their use is limited in real practice settings. We examined the association of self-reported adherence using a visual analogue scale (VAS) with objective BP adherence and sustained virologic response (SVR) among people who inject drugs. Methods: We conducted secondary analyses using a subset of participants (N = 493) from the per-protocol sample of the HERO study, a pragmatic randomized trial of HCV treatment interventions that used both VAS and BP to measure adherence to a 12-week sofosbuvir/velpatasvir DAA regimen. Multivariable mixed-effects regression models tested the association of self-report adherence level with longitudinal weekly objective adherence. Multivariable logistic regression tested the association of self-report adherence with SVR. Results: The average VAS and BP adherences were 95.1 % (SD = 8.9 %) and 76.0 % (16.0 %), respectively, and the proportion of the participants achieving SVR was 92.9 %. The estimated adjusted mean objective adherence was significantly different (−16 %; 95 % CI: −22 %, −11 %, p < .001) between participants with 100 % and <80 % VAS adherence. The likelihood of SVR was significantly lower for those with <80 % VAS adherence [adjusted OR = 0.07; 95 % CI: 0.02, 0.24; p < .001] compared to those with 100 %. Conclusion: Self-reported adherence overestimated objective adherence. However, higher self-report adherence was significantly associated with higher objective adherence. Also, self-reported adherence ≥80 % was significantly associated with SVR. Thus, the self-report measure has utility as a monitoring tool for adherence during DAA treatment.