Out-of-Pocket Costs and Initiation of HCV Treatment Among US Medicare Beneficiaries Receiving Low-Income Subsidy

OBJECTIVES: In the U.S., Medicare beneficiaries receiving low-income subsidy (LIS) for pharmacy benefits (Part D) face disproportionate disease burdens of Hepatitis C Virus (HCV), yet may be especially vulnerable to high OOP costs for the direct-acting antivirals (DAAs) for HCV. We employed an innovative design to examine changes in DAA initiation in response to increased OOP costs among Part D LIS enrollees.

METHODS: Using 2014-2019 Medicare data for LIS enrollees 18 or older, we assigned hypothetical OOP costs to each patient newly diagnosed with HCV (index patient) irrespective of actual DAA initiation, in two steps: 1. We matched each index patient with patients who initiated DAAs based on clinical characteristics and time of diagnosis, and assigned the DAA regimen of a randomly selected, matched patient to the index patient; 2. Within each of three LIS cost-sharing groups, we matched the index patient with patients who initiated DAAs with the same regimen and assigned the OOP costs facing a randomly selected, matched patient. We conducted a regression analysis for each cost-sharing group to estimate changes in DAA initiation in response to increases in the OOP costs.

RESULTS: Rates of treatment initiation were 29%, 33%, and 36%, and, mean [SD] of assigned OOP costs were $3.07 [1.28], $6.45 [2.56], and $868.76 [448.99], among the low, medium, and high cost-sharing groups, respectively. A one-SD increase in OOP costs from the mean was associated with a reduction of 0.73 percentage points (2.5% relative reduction; p<0.001) among the low cost-sharing group, 1.6 percentage points (4.8%; p<0.001) among the medium cost-sharing group, and 2.8 percentage points (7.8%; p=0.066) among the high cost-sharing group.

CONCLUSIONS: Even small increases in OOP costs may restrict access to DAAs for low-income Medicare beneficiaries. Further reduction in OOP costs may be necessary to achieve the high treatment rates needed for HCV elimination.