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Completed

NCT Number: NCT03219528

A Longitudinal Study to Identify IBS Phenotypes Using Fecal Microbiota and Hydrogen Breath Testing

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.

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Key information

Conditions

Irritable Bowel Syndrome Colonic Diseases Colonic Diseases, Functional Diarrhea Digestive System Diseases Gastrointestinal Diseases Intestinal Diseases Pathological Conditions, Signs and Symptoms Signs and Symptoms Signs and Symptoms, Digestive

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 4

Primary location

University of Michigan

Ann Arbor, Michigan, 48109, United States

About this study

Diarrhea-predominant irritable bowel syndrome (IBS-D) is a highly prevalent but poorly understood condition with limited treatment options. Recent evidence has established small intestinal bacterial overgrowth (SIBO) and alterations in fecal microbiota as potential etiologies in the pathogenesis of IBS-D. 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 [1-4]. It has been postulated that limited responses to therapies may stem from failure to identify distinct subgroups in IBS-D stratified by gut microbial profiles. In this proposal, participants with IBS-D will be randomized to receive either rifaximin or low FODMAP dietary intervention. The results of fecal microbiota-derived data as well as hydrogen breath tests will then be longitudinally followed to define SIBO. These methods will be used to test the hypotheses that: (i) distinct IBS-D phenotypes can be generated by defining fecal microbial populations as well as delineating the presence or absence of SIBO; and (ii) longitudinal analyses using microbe-derived metrics and SIBO status may relate to response to treatment with rifaximin or low FODMAP dietary intervention.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

Adult subjects greater than or equal to 18 years of age who meet Rome IV criteria for diarrhea-predominant irritable bowel syndrome (IBS-D).

Prior colonoscopy or sigmoidoscopy within the past 2 years with random colon biopsies to exclude the presence of microscopic colitis.

IBS medications, including anti-depressants, will be allowed if the dose has been stable for at least 1 month before inclusion. Medications will be carefully tracked to follow any potential confounding issues.

Exclusion criteria

Underlying celiac disease, inflammatory bowel disease, or other organic disease that could explain their symptoms.

Subjects with a history of GI tract surgery, except for cholecystectomy or appendectomy, will also be excluded from the study.

Women who are pregnant or breastfeeding Antibiotics taken within 3 months prior to enrollment will not be permitted. Subjects on probiotics must discontinue their use at least 1 month prior to enrollment.

Subjects who have previously received formal dietary education for IBS, including a low FODMAP diet, or previously received antibiotics, including rifaximin, for treatment of IBS-D will be excluded from the study.

Treatment and study plan

Rifaximin 550 MG

Drug

Rifaximin 550 mg three times daily for 14 days

Low fodmap diet

Other

Low FODMAP dietary intervention for 4 weeks

Primary outcomes

  1. Change in Mean Daily Abdominal Pain

    Time frame: 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.

  2. Change in Mean Daily Bloating

    Time frame: 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.

Secondary outcomes

  1. Change in Irritable Bowel Syndrome (IBS) Symptom Severity Scale

    Time frame: Baseline, Week 5

    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.

  2. Change in Gastrointestinal System Ratings Scale (GSRS)

    Time frame: 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.

  3. Change in Stool Form

    Time frame: 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.

  4. Change in Psychological Function

    Time frame: 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.

  5. Change in Irritable Bowel Syndrome Quality of Life Instrument (IBS-QOL)

    Time frame: 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.

  6. 24-hour Diet Recall/Intake - Lactose

    Time frame: Baseline, Week 5

    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.

  7. 24-hour Diet Recall/Intake - Gluten

    Time frame: Baseline, Week 5

    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.

Other outcomes

  1. Glucose Breath Tests

    Time frame: 4 weeks

    Glucose breath tests (GBT) will be performed at baseline and repeated after intervention

  2. Fecal Microbiota

    Time frame: 4 weeks

    Changes in fecal microbial diversity after intervention will be compared with baseline.

Sponsors and collaborators

Lead sponsor

University of Michigan

Other

Collaborators

  • Michigan Institute for Clinical and Health Research (MICHR)
  • National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)

Registry information

Important dates

Study start
2018
Primary completion
2024
Study completion
2024
First posted
Jul 17, 2017
Registry last updated
Apr 27, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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