PGI9 - Rifaximin and Eluxadoline Utilization for Irritable Bowel Syndrome with Diarrhea (IBS-D) in the United States and Budget Impact Analysis of Switching from Eluxadoline to Rifaximin

Abstract

Irritable bowel syndrome with diarrhea (IBS-D) is a functional bowel disorder with a prevalence of ~3.3% in the US. Accumulating evidence suggests altered gut microbiota may contribute to IBS-D symptoms. Rifaximin and eluxadoline are indicated for the treatment of IBS-D; however, they differ in mechanism of action and duration of treatment (up to 3 courses of treatment for rifaximin vs. potentially chronic treatment with eluxadoline). The aim of the study was to evaluate the utilization of rifaximin and eluxadoline using a claims analysis and estimate the budget impact of switching from eluxadoline to rifaximin from a US payer perspective. Healthcare claims from Symphony Health's Integrated Dataverse® database were analyzed for patients newly initiated on rifaximin or eluxadoline with an IBS-D diagnosis within the same month of the prescription. Patients were tracked over 12 months to identify the average annual number of prescriptions. Based on rifaximin and eluxadoline utilization from the claims analysis, IBS-D prevalence, and drug wholesale acquisition costs, the annual budget impact of switching from eluxadoline to rifaximin was calculated for a 1,000,000 member health plan. The annual number of prescriptions per patient was 1.4 and 3.7, and the annual pharmacy cost per patient was $1,902 and $3,872 for rifaximin and eluxadoline, respectively, with similar outpatient visit costs. For an estimated number of 1,320 patients with IBS-D using eluxadoline, the switch to rifaximin results in savings of $2,600,220 ($0.22 per-member per-month [PMPM]). In sensitivity analyses where the number of prescriptions varied from 1-3 for rifaximin and 1-12 for eluxadoline simultaneously, potential savings ranged from ~$15 million ($1.23 PMPM) to ~-$4 million (-$0.33 PMPM). Due to the shorter expected duration of therapy of rifaximin (up to three 14-day courses) vs. potential for continuous dosing of eluxadoline, rifaximin may be cost saving for the treatment of IBS-D.