Hepatitis C Virus Direct-Acting Antiviral Treatment Adherence Patterns and Sustained Viral Response Among People Who Inject Drugs Treated in Opioid Agonist Therapy Programs

Background. Adequate medication adherence is critical for achieving sustained viral response (SVR) of hepatitis C virus (HCV) among people who inject drugs (PWID). However, it is less known which patterns of direct-acting antiviral (DAA) treatment adherence are associated with SVR in this population or what factors are associated with each pattern. Methods. The randomized 3-arm PREVAIL study used electronic blister packs to obtain daily time frame adherence data in opiate agonist therapy program settings. Exact logistic regressions were applied to test the associations between SVR and 6 types of treatment adherence patterns. Results. Of the 113 participants treated with combination DAAs, 109 (96.5%) achieved SVR. SVR was significantly associated with all pattern parameters except for number of switches between adherent and missed days: total adherent daily doses (exact adjusted odds ratio [AOR] = 1.12; 95% confidence interval [CI] = 1.04–1.22), percent total doses (1.09; 1.03–1.16), days on treatment (1.16; 1.05–1.32), maximum consecutive adherent days (1.34; 1.06–2.04), and maximum consecutive nonadherent days (0.85; .74–.95 = 0.003). SVR was significantly associated with total adherent doses in the first 2 months of treatment, it was not in the last month. While alcohol intoxication was significantly associated with frequent switches, drug use was not associated with any adherence pattern. Conclusions. Consistent maintenance of adequate total dose adherence over the entire course of HCV treatment is important in achieving SVR among PWID. Additional integrative addiction and medical care may be warranted for treating PWID who experience alcohol intoxication.