S1185 A 2-Week Course of Rifaximin Improves Symptoms of Irritable Bowel Syndrome With Diarrhea (IBS-D) in Patients With Comorbid Anxiety

Introduction: Anxiety, a common comorbidity in patients with IBS-D, can negatively impact gastrointestinal symptoms. Data are limited on the potential impact of anxiety on medications targeting IBS-D symptoms. This post hoc analysis evaluated the efficacy of rifaximin, indicated for the treatment of adults with IBS-D, in individuals with comorbid anxiety. Methods: Data were pooled from 2 identically designed, phase 3, randomized, double-blind trials. Adults with IBS-D were randomly assigned to receive rifaximin 550 mg or placebo 3 times daily for 2 weeks, followed by a 4-week treatment-free period to assess response, and an additional 6 weeks of follow-up. This population was stratified post hoc by medical history of anxiety. Abdominal pain/discomfort and bloating were separately rated daily (0 [“not at all”] to 6 [“a very great deal”]) and stool consistency was scored from 1 (“very hard”) to 5 (“watery”). Efficacy assessments included the percentage of patients with adequate global IBS symptom relief (“In regards to your IBS symptoms, compared to the way you felt before you started study medication, have you, in the past 7 days, had adequate relief of your IBS symptoms?) and composite response (≥30% decrease from baseline in weekly mean abdominal pain/discomfort score plus a weekly mean stool consistency score <4) during ≥2 of first 4 weeks post-treatment. Results: A total of 232 patients had comorbid anxiety (rifaximin [n = 114]; placebo [n = 118]) and most were women (84.2%; 79.7%); the mean (SD) age was 45.0 (14.4) and 44.9 (13.7) years, respectively. Baseline scores in the rifaximin and placebo groups were similar for mean daily abdominal pain/discomfort (3.3; 3.2), bloating, (3.4; 3.3), and stool consistency (3.9; 3.9). A greater percentage of patients with comorbid anxiety treated with rifaximin had adequate relief of global IBS symptoms vs placebo (43.0% vs 28.0%; relative difference = 42.3%; absolute difference = 15.0%; P = 0.02) and were composite responders (46.5% vs 33.9%; relative difference = 31.3%; absolute difference = 12.6%; P = 0.05). Significantly greater improvements from baseline in abdominal pain/discomfort were observed for rifaximin vs placebo at most timepoints through 10 weeks of post-treatment follow-up (P < 0.05). Conclusion: A 2-week course of rifaximin demonstrated improvements in symptoms of IBS-D compared with placebo in adults with comorbid anxiety, further supporting its potential as a treatment option for this patient population.