Rifaximin Significantly Improves Quality of Life Versus Placebo in Patients with Diarrhea-Predominant Irritable Bowel Syndrome

Abstract

Purpose: A randomized, double-blind, multicenter, phase 2 trial showed the nonabsorbed antibiotic rifaximin 550 mg twice daily (b.i.d.) significantly improved IBS symptoms versus placebo in patients with diarrhea-predominant IBS (IBS-D). Secondary analyses from that study evaluated the efficacy of rifaximin for improving quality of life (QOL) measures in patients with IBS-D. Methods: Adults diagnosed with IBS-D (Rome II criteria) received rifaximin 550 mg b.i.d. or placebo for 14 days. Both groups received placebo for an additional 14 days after the initial 2-week treatment. Quality of life was assessed with the 34-item IBS-QOL questionnaire at baseline and 4 weeks after initiating treatment. Each item was scored on a 5-point scale (1 = not at all; 2 = slightly; 3 = moderately; 4 = quite a bit; and 5 = extremely or a great deal). Results for composite and subscale scores were converted to a scale ranging from 0 to 100, with higher scores indicating better QOL. Analyses included all randomized patients. Results: A total of 388 patients were treated at 75 centers in the United States; 191 patients received rifaximin and 197 patients received placebo during the 2-week initial treatment period. The mean improvement from baseline in overall QOL scores at week 4 was significantly greater with rifaximin compared with placebo (Table). Patients in the rifaximin group reported significantly greater mean improvement from baseline in QOL scores for dysphoria, body image, health worry, social reaction, and relationship subscales compared with placebo (Table). Rifaximin was well tolerated, with similar incidence of adverse events compared with placebo.Table: Mean Change From Baseline in IBS-QOL Scores at Week 4.Conclusion: In patients with IBS-D, rifaximin 1100 mg/d for 14 days significantly improved QOL measures compared with placebo. These findings, along with previously reported data, suggest a potential therapeutic role for rifaximin 550 mg b.i.d. for improving symptoms and QOL in patients with IBS-D.