Causes of treatment failure for hepatitis C in the era of direct-acting antiviral therapy.

Hepatitis C therapy in the era of the newer direct-acting antiviral agents has radically changed our treatment schemes by achieving very high rates of sustained virological response. However, treatment with direct antiviral agents fails in a subgroup of patients. This group of so-called difficult-to-treat individuals is the subject of this paper, which reviews the causes of virological failure, their clinical implications, and some final recommendations.