Abstract

Although therapy with direct-acting antiviral (DAA) agents achieves high hepatitis C virus (HCV) cure rates and is forgiving of missed doses, certain patient populations, such as people who inject drugs (PWID), are often denied therapy because of a perceived high risk of nonadherence. However, a relationship between adherence to DAAs for various patient populations and efficacy has not been well defined. The lack of a standardized method for evaluating adherence complicates making comparisons between studies, making it difficult to develop and implement novel measures that may improve adherent behavior. Traditional methods for assessing adherence may overestimate medication adherence, while newer, technology-based methods may assist with accurately assessing and maintaining patient adherence to therapy. Data demonstrate that special populations of patients with HCV, such as PWID, can be successfully treated, with relatively high rates of sustained virologic response (SVR) despite less-than-optimal adherence. While rates of adherence, and subsequently SVR, can be improved, antiviral therapy should not be withheld because of fear of nonadherence. This article addresses medication adherence and forgiveness of DAA regimens, such as sofosbuvir/velpatasvir and glecaprevir/pibrentasvir, in different patient populations with HCV. Considerations in evaluating adherence in HCV therapy and available methods for assessing adherence are detailed.