OBJECTIVES: Longer rifaximin retention is associated with lower incidence of HE recurrence and mortality. Despite known benefits of rifaximin, it remains underutilized. The aim was to assess out-of-pocket costs for rifaximin and its impact on treatment retention.

METHODS: This retrospective cohort study used IBM MarketScan Commercial Claims and Encounters database. Patients were included if they were 18 to 64 years old, had a diagnosis code for hepatic encephalopathy, and were initiated on rifaximin during the study period (2011 - 2021). Poisson regression was applied to analyze the relationship between out-of-pocket cost and rifaximin retention, defined as at least 80% of days covered with rifaximin supply at three different thresholds (180, 360, and 540 days). Models controlled for patient characteristics including age, sex, geographic region, insurance type, and comorbid conditions.

RESULTS: Of 4,079 patients in the 180-day threshold analysis, rifaximin retention rate was 42.4% (n=1,730). Rifaximin retention decreased to 25.3% at 360 days, and 16.1% at 540 days. Each $100 increase in 30-day out-of-pocket rifaximin cost was associated with a 13% decrease in 180-day treatment retention rate (RR 0.87, 95% CI 0.83 – 0.92). Lower treatment retention was noted in younger patients(18 - 34 years of age) (RR 0.60, 95% CI 0.41 – 0.90), those with metastatic cancer (RR 0.69, 95% CI 0.51 – 0.93), and those with depression (RR 0.87, 95% CI 0.78 – 0.98).

CONCLUSIONS: Higher 30-day out-of-pocket cost was significantly associated with lower treatment retention. Policies regarding out-of-pocket cost cap should be considered to improve treatment retention and clinical outcomes in patients with hepatic encephalopathy.