Medication Adherence to Direct Acting Anti-Viral Agents Among Hepatitis C Virus Infected Patients in the United States

OBJECTIVES: The advent of direct-acting antiviral agents (DAAs) has revolutionized Hepatitis C virus (HCV) treatment. However, real-world adherence patterns to DAAs remain understudied. This study examines the adherence rate and factors associated with adherence to DAAs among HCV patients.

METHODS: This was a retrospective cohort study involving HCV-infected adult patients who were incident users of DAAs from the 2017-2019 MarketScan Commercial database. The earliest prescription date for DAAs was defined as the index date with a 12-month washout period. HCV patients were required to enroll continuously for a 12-month pre-index and 3-month post-index date. Medication adherence was measured using the proportion of days supply (PDC). Multivariable logistic regression was used to identify factors associated with optimal adherence (≥ 80%) based on the conceptual framework of the Anderson Behavioral Model (ABM).

RESULTS: The study included 4,193 HCV-infected patients receiving DAAs. The mean age was 50.51±12 years. Most of the HCV-infected patients were males (60.07%), lived in the South (52.27%), and enrolled in a Preferred Provider Organization (PPO) plan (51.74%). Over 66.61% of HCV-infected patients had optimal adherence (≥ 80%) to DAAs, with an average PDC of 77.78%(±32.2%). Multivariate logistic regression found that HCV-infected patients with ≥2 comorbid conditions were more likely [adjusted odds ratio [aOR] 2.28 (95% CI:1.81-2.88)] to be adherent than those without comorbidity. Patients with hypertension (aOR: 3.38; 95%CI: 2.87-3.99) and diabetes mellitus (aOR: 1.96; 95%CI: 1.53-2.50), and those with other chronic viral infections (HBV and HIV; aOR: 2.76; 95%CI: 1.87-4.10) were also more likely to be adherent to DAAs.

CONCLUSIONS: About two-thirds of the HCV-infected patients had optimal medication adherence, with comorbidities playing a critical role in medication adherence. Concerted efforts are needed to increase DAA adherence with an opportunity to utilize positive triggers like comorbidities to lower patients’ risk of developing resistance to future treatments.