18 and older, any sex, with Irritable Bowel Syndrome. Patients with the condition only — healthy volunteers not accepted.
Results — posted to ClinicalTrials.gov
Per-arm endpoint measurements with 95% confidence intervals where reported. Source: trial results section.
Change in Mean Daily Abdominal PainPrimary· Baseline, Week 5
Change in mean daily abdominal pain was measured using a visual analog scale (VAS) after intervention compared with baseline. VAS was a scale of 0 to 10, with higher numbers indicating a higher degree of pain; 0 indicated no pain and 10 indicated severe pain.
The IBS Symptom Severity Scale was comprised of 5 questions each of which was on a scale of 0 to 100, with higher scores indicating more severe symptoms. The total range of the scale was 0 to 500, with 0 meaning no IBS symptoms and 500 indicating severe IBS symptoms.
Baseline
Group
Value
95% CI
Rifaximin
281.3
± 81.0
Low FODMAP Group
272.0
± 65.1
Week 5
Group
Value
95% CI
Rifaximin
209.3
± 81.8
Low FODMAP Group
194.7
± 79.1
Change in Gastrointestinal System Ratings Scale (GSRS)Secondary· Baseline, Week 5
The GSRS was a disease-specific instrument of 15 items combined into five symptom clusters depicting Reflux, Abdominal Pain, Indigestion, Diarrhea, and Constipation. The GSRS had a seven-point graded Likert scale where 1 represents absence of troublesome symptoms and 7 represents very troublesome symptoms. The total range of the scale is 15 to 105 with 15 meaning low symptom burden and 105 meaning high symptom burden.
Baseline
Group
Value
95% CI
Rifaximin
52.0
± 13.2
Low FODMAP Group
52.1
± 13.3
Week 5
Group
Value
95% CI
Rifaximin
40.7
± 11.0
Low FODMAP Group
40.1
± 12.2
Change in Stool FormSecondary· Baseline, Week 5
The Bristol Stool Form Scale was a diagnostic tool used to assess various digestive issues based on the type and shape of stool. The total range of the scale was 1 to 7, with 1 indicating hard stool and 7 indicating liquid stool.
Baseline
Group
Value
95% CI
Rifaximin
5.6
± 0.8
Low FODMAP Group
5.6
± 0.8
Week 5
Group
Value
95% CI
Rifaximin
5.0
± 1.1
Low FODMAP Group
5.3
± 0.9
Change in Psychological FunctionSecondary· Baseline, Week 5
The PHQ-9 was a multipurpose instrument for screening, diagnosing, monitoring, and measuring the severity of depression. It is comprised of 9 questions, each ranging from 0 to 3 with higher values indicating more severe depression symptoms. The total range of the scale was 1 to 27, with 1 indicating no or minimal depression and 27 indicating severe depression.
Baseline
Group
Value
95% CI
Rifaximin
8.6
± 6.5
Low FODMAP Group
8.3
± 6.2
Week 5
Group
Value
95% CI
Rifaximin
6.2
± 4.9
Low FODMAP Group
5.8
± 4.3
Change in Irritable Bowel Syndrome Quality of Life Instrument (IBS-QOL)Secondary· Baseline, Week 5
IBS-QOL was a condition-specific instrument for assessing health-related quality of life among persons with IBS. The IBS-QOL was comprised of 34 questions, each with a 5-point scale where the higher the value indicated the higher quality of life. The total range of the scale was 0 to 100, with 0 indicating no quality of life and 100 indicating extremely good quality of life.
Participants completed entries using the Nutrition Data System for Research (NDSR), which was a Windows-based dietary analysis program designed for the collection and analyses of 24-hour dietary recalls, food records, menus, and recipes. The NDSR was incapable of collecting data on all FODMAP-type foods, aside from lactose and gluten. The results represent data from lactose as a surrogate for all other FODMAP foods.
Baseline
Group
Value
95% CI
Rifaximin
4.1
± 5.5
Low FODMAP Group
7.3
± 9.6
Week 5
Group
Value
95% CI
Rifaximin
5.1
± 6.7
Low FODMAP Group
1.4
± 2.3
Change in Mean Daily BloatingPrimary· Baseline, Week 5
Change in mean daily bloating was measured using a visual analog scale (VAS) after intervention compared with baseline. VAS was a scale of 0 to 10, with higher numbers indicating a higher degree of bloating; 0 indicated no bloating and 10 indicated severe bloating.
Participants completed entries using the Nutrition Data System for Research (NDSR), which was a Windows-based dietary analysis program designed for the collection and analyses of 24-hour dietary recalls, food records, menus, and recipes. The NDSR was incapable of collecting data on all FODMAP-type foods, aside from lactose and gluten. The results represent data from gluten as a surrogate for all other FODMAP foods.
Baseline
Group
Value
95% CI
Rifaximin
6.7
± 6.0
Low FODMAP Group
5.7
± 5.6
Week 5
Group
Value
95% CI
Rifaximin
7.2
± 6.5
Low FODMAP Group
1.7
± 4.2
Adverse events — posted to ClinicalTrials.gov
Time frame: 5 weeks.
Reporting threshold: 0%.
Adverse-event reports describe events observed during the trial — not all are caused by the drug.
Diarrhea-predominant irritable bowel syndrome (IBS-D) is a highly prevalent but poorly understood condition with limited treatment options. Current therapies, including a nonabsorbable antibiotic rifaximin or diet low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAP), show efficacy in 50% or less of patients. In this proposal, participants with IBS-D will be randomized to receive either rifaximin or low FODMAP dietary intervention.
Publications & conference data
1 peer-reviewed publication reference this trial (live from Europe PMC):
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Publications: Europe PMC API search by NCT ID, retrieved 10 June 2026
Drug + disease cross-links: matched in real time against Drug Landscape's normalised drug + company + condition tables
Sponsor: as reported to ClinicalTrials.gov by University of Michigan
Last refreshed: 27 April 2025
Drug Landscape aggregates and links these public records for informational use only. Always verify against the primary source before clinical or regulatory decisions. Canonical URL: https://druglandscape.com/trial/NCT03219528.