OBJECTIVES: Rifaximin is the only United States (US) Food and Drug Administration approved therapy for reducing the risk of recurrent overt hepatic encephalopathy (OHE) in adults. A study by Jesudian AB et al. (2020) showed that rifaximin ± lactulose (vs. lactulose monotherapy) is cost-effective (incremental cost-effectiveness ratio [ICER] of $29,161/quality adjusted life years [QALY] gained). The authors used mortality estimates from a single-arm, open-label study. The objectives of the current study were to: 1) identify updated rifaximin-associated OHE mortality estimates for US patients and; 2) conduct scenario analyses to assess the robustness of the original model by measuring the impact of assuming no/updated mortality estimates on the ICER of rifaximin for OHE.

METHODS: A targeted literature review (TLR; as of August 2022) was conducted using PubMed and Ovid (MEDLINE and EMBASE) databases to identify studies reporting the US mortality rates for OHE patients treated with rifaximin or lactulose. In the scenario analyses, the impact of assuming (rifaximin-associated): a) no mortality benefits and b) updated mortality estimates on the ICER (2018 dollars) of rifaximin treatment for OHE was assessed.

RESULTS: The TLR yielded a total of 19 relevant studies out of the 7,500 studies identified during the initial search. Of the 19 studies, only 2 US studies (Bajaj et al. 2019; Landaverde et al. 2020) were published after the Jesudian AB study was conducted. In the scenario analysis, assuming no rifaximin-associated mortality benefits yielded an ICER of $29,163-$29,914/QALY gained. Further, using the mortality data from Bajaj et al. and Landaverde et al. yielded an ICER of $29,244 and $29,155, respectively.

CONCLUSIONS: Assuming no rifaximin-associated mortality and using mortality estimates from more recent US studies demonstrates that mortality was not a key model parameter and does not significantly impact the ICER for rifaximin for OHE. This finding corroborates the robustness of the original model’s ICER estimate.