Understanding real-world adherence in the directly acting antiviral era: A prospective evaluation of adherence among people with a history of drug use at a community-based program in Toronto, Canada

Abstract

Background: Direct acting antiviral (DAA) treatments for Hepatitis C (HCV) are now widely available with sustained virologic response (SVR) rates of >90%. A major predictor of response to DAAs is adherence, yet few real-world studies evaluating adherence among marginalized people who use drugs and/or alcohol exist. This study evaluates patterns and factors associated with non-adherence among marginalized people with a history of drug use who were receiving care through a primary care, community-based HCV treatment program where opiate substitution is not offered on-site.

Methods: Prospective evaluation of chronic HCV patients initiating DAA treatment. Self-report medication adherence questionnaires were completed weekly. Pre/post treatment questionnaires examined socio-demographics, program engagement and substance use. Missing adherence data was counted as a missed dose.

Results: Of the 74 participants, who initiated treatment, 76% were male, the average age was 54 years, 69% reported income from disability benefits, 30% did not have stable housing and only 24% received opiate substitution therapy. Substance use was common in the month prior to treatment initiation with, 11% reported injection drug use, 30% reported non-injection drug use and 18% moderate to heavy alcohol use. The majority (85%) were treatment naïve, with 76% receiving sofosbuvir/ledipasvir (8-24 weeks) and 22% Sofosbuvir/Ribarvin (12-24 weeks). The intention to treat proportion with SVR12 was 87% (60/69). In a modified ITT analysis (excluding those with undetectable RNA at end of treatment), 91% (60/66) achieved SVR12. Overall, 89% of treatment weeks had no missed doses. 41% of participants had at least one missed dose. In multivariate analysis the only factor independently associated with weeks with missed doses was moderate to heavy alcohol use (p=0.05).

Conclusion: This study demonstrates that strong adherence and SVR with DAAs is achievable, with appropriate supports, even in the context of substance use, and complex health/social issues.

Keywords: Adherence; Community-based treatment models; Direct acting antivirals; Hepatitis C; Injection drug use.