High rifaximin out-of-pocket costs are associated with decreased treatment retention among patients with hepatic encephalopathy

Background and Aims: Hepatic encephalopathy (HE) is associated with significant morbidity and mortality for those with cirrhosis. Despite the known benefits of rifaximin use for HE, treatment retention remains low. This study aimed to evaluate the impact of out-of-pocket (OOP) rifaximin cost on treatment retention among commercially insured patients in the United States. Methods: Adult patients with cirrhosis and HE were identified from the IBM MarketScan claims database. Those who began rifaximin treatment between January 1, 2011, and December 1, 2021 were included. Regression models were used to analyze the relationship between patients' 30-day OOP rifaximin cost and rifaximin retention (≥ 80% eligible days with rifaximin supply) at 180, 360, and 540 days. Models were controlled for patient demographic and clinical characteristics including age, sex, comorbid conditions, Charlson comorbidity index (CCI), and lactulose use. Results: A total of 6839 adult patients were included. Most patients were between 55 and 64 years (57.1%), male (60.4%), and living in urban settings (84.6%). Treatment retention was low for all time periods; retention rates for rifaximin were 42%, 25%, and 16% at 180, 360, and 540 days, respectively. In multivariable analysis, 30-day OOP costs of ≥ $150 were associated with a decreased likelihood of rifaximin retention at 180, 360, and 540 days [relative risk (RR) = 0.67, RR = 0.62, and R = 0.60, respectively]. Younger age was associated with reduced treatment retention for all time periods. Metastatic cancer and depression were associated with reduced treatment retention at 180 days (RR = 0.70 and RR = 0.87, respectively). Conclusions: Rates of rifaximin treatment retention are low despite the known benefits of rifaximin use for breakthrough HE. High 30-day OOP cost is associated with reduced rifaximin treatment retention.