Trial Outcomes & Findings for A Longitudinal Study to Identify IBS Phenotypes Using Fecal Microbiota and Hydrogen Breath Testing (NCT NCT03219528)
NCT ID: NCT03219528
Last Updated: 2025-04-27
Results Overview
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.
COMPLETED
PHASE4
74 participants
Baseline, Week 5
2025-04-27
Participant Flow
Participant milestones
| Measure |
Rifaximin
Rifaximin 550 mg three times daily for 14 days
Rifaximin 550 MG: Rifaximin 550 mg three times daily for 14 days
|
Low FODMAP Group
Low FODMAP diet for 4 weeks
Low FODMAP Diet: Low FODMAP dietary intervention for 4 weeks
|
|---|---|---|
|
Overall Study
STARTED
|
38
|
36
|
|
Overall Study
Actual Treatment Begun
|
36
|
29
|
|
Overall Study
COMPLETED
|
29
|
28
|
|
Overall Study
NOT COMPLETED
|
9
|
8
|
Reasons for withdrawal
| Measure |
Rifaximin
Rifaximin 550 mg three times daily for 14 days
Rifaximin 550 MG: Rifaximin 550 mg three times daily for 14 days
|
Low FODMAP Group
Low FODMAP diet for 4 weeks
Low FODMAP Diet: Low FODMAP dietary intervention for 4 weeks
|
|---|---|---|
|
Overall Study
Lost to Follow-up
|
5
|
4
|
|
Overall Study
Withdrawal by Subject
|
4
|
4
|
Baseline Characteristics
A Longitudinal Study to Identify IBS Phenotypes Using Fecal Microbiota and Hydrogen Breath Testing
Baseline characteristics by cohort
| Measure |
Rifaximin
n=38 Participants
Rifaximin 550 mg three times daily for 14 days
Rifaximin 550 MG: Rifaximin 550 mg three times daily for 14 days
|
Low FODMAP Group
n=36 Participants
Low FODMAP diet for 4 weeks
Low FODMAP Diet: Low FODMAP dietary intervention for 4 weeks
|
Total
n=74 Participants
Total of all reporting groups
|
|---|---|---|---|
|
Age, Continuous
|
44.2 years
STANDARD_DEVIATION 17.9 • n=5 Participants
|
44.1 years
STANDARD_DEVIATION 16.4 • n=7 Participants
|
44.1 years
STANDARD_DEVIATION 17.0 • n=5 Participants
|
|
Sex: Female, Male
Female
|
30 Participants
n=5 Participants
|
26 Participants
n=7 Participants
|
56 Participants
n=5 Participants
|
|
Sex: Female, Male
Male
|
8 Participants
n=5 Participants
|
10 Participants
n=7 Participants
|
18 Participants
n=5 Participants
|
|
Ethnicity (NIH/OMB)
Hispanic or Latino
|
3 Participants
n=5 Participants
|
2 Participants
n=7 Participants
|
5 Participants
n=5 Participants
|
|
Ethnicity (NIH/OMB)
Not Hispanic or Latino
|
35 Participants
n=5 Participants
|
34 Participants
n=7 Participants
|
69 Participants
n=5 Participants
|
|
Ethnicity (NIH/OMB)
Unknown or Not Reported
|
0 Participants
n=5 Participants
|
0 Participants
n=7 Participants
|
0 Participants
n=5 Participants
|
|
Race (NIH/OMB)
American Indian or Alaska Native
|
0 Participants
n=5 Participants
|
1 Participants
n=7 Participants
|
1 Participants
n=5 Participants
|
|
Race (NIH/OMB)
Asian
|
1 Participants
n=5 Participants
|
0 Participants
n=7 Participants
|
1 Participants
n=5 Participants
|
|
Race (NIH/OMB)
Native Hawaiian or Other Pacific Islander
|
0 Participants
n=5 Participants
|
0 Participants
n=7 Participants
|
0 Participants
n=5 Participants
|
|
Race (NIH/OMB)
Black or African American
|
2 Participants
n=5 Participants
|
2 Participants
n=7 Participants
|
4 Participants
n=5 Participants
|
|
Race (NIH/OMB)
White
|
34 Participants
n=5 Participants
|
33 Participants
n=7 Participants
|
67 Participants
n=5 Participants
|
|
Race (NIH/OMB)
More than one race
|
1 Participants
n=5 Participants
|
0 Participants
n=7 Participants
|
1 Participants
n=5 Participants
|
|
Race (NIH/OMB)
Unknown or Not Reported
|
0 Participants
n=5 Participants
|
0 Participants
n=7 Participants
|
0 Participants
n=5 Participants
|
|
Region of Enrollment
United States
|
38 Participants
n=5 Participants
|
36 Participants
n=7 Participants
|
74 Participants
n=5 Participants
|
|
Body Mass Index (BMI)
|
29.7 kg/m^2
STANDARD_DEVIATION 8.72 • n=5 Participants
|
29.8 kg/m^2
STANDARD_DEVIATION 8.18 • n=7 Participants
|
29.8 kg/m^2
STANDARD_DEVIATION 8.41 • n=5 Participants
|
PRIMARY outcome
Timeframe: Baseline, Week 5Population: Some participants who were randomized to an arm withdrew or were lost to follow up before receiving an intervention. The number of participants analyzed at each time point is based on a modified intent to treat (mITT) analysis.
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.
Outcome measures
| Measure |
Rifaximin
n=36 Participants
Rifaximin 550 mg three times daily for 14 days
Rifaximin 550 MG: Rifaximin 550 mg three times daily for 14 days
|
Low FODMAP Group
n=29 Participants
Low FODMAP diet for 4 weeks
Low FODMAP Diet: Low FODMAP dietary intervention for 4 weeks
|
|---|---|---|
|
Change in Mean Daily Abdominal Pain
Baseline
|
5.2 score on a scale
Standard Deviation 1.8
|
5.3 score on a scale
Standard Deviation 1.6
|
|
Change in Mean Daily Abdominal Pain
Week 5
|
3.9 score on a scale
Standard Deviation 2.5
|
3.8 score on a scale
Standard Deviation 2.0
|
PRIMARY outcome
Timeframe: Baseline, Week 5Population: Some participants who were randomized to an arm withdrew or were lost to follow up before receiving an intervention. The number of participants analyzed at each time point is based on a mITT analysis.
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.
Outcome measures
| Measure |
Rifaximin
n=36 Participants
Rifaximin 550 mg three times daily for 14 days
Rifaximin 550 MG: Rifaximin 550 mg three times daily for 14 days
|
Low FODMAP Group
n=29 Participants
Low FODMAP diet for 4 weeks
Low FODMAP Diet: Low FODMAP dietary intervention for 4 weeks
|
|---|---|---|
|
Change in Mean Daily Bloating
Baseline
|
4.9 score on a scale
Standard Deviation 1.9
|
5.1 score on a scale
Standard Deviation 2.2
|
|
Change in Mean Daily Bloating
Week 5
|
4.0 score on a scale
Standard Deviation 2.4
|
3.7 score on a scale
Standard Deviation 2.1
|
SECONDARY outcome
Timeframe: Baseline, Week 5Population: Some participants who were randomized to an arm withdrew or were lost to follow up before receiving an intervention. The number of participants analyzed at each time point is based on a mITT analysis.
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.
Outcome measures
| Measure |
Rifaximin
n=36 Participants
Rifaximin 550 mg three times daily for 14 days
Rifaximin 550 MG: Rifaximin 550 mg three times daily for 14 days
|
Low FODMAP Group
n=29 Participants
Low FODMAP diet for 4 weeks
Low FODMAP Diet: Low FODMAP dietary intervention for 4 weeks
|
|---|---|---|
|
Change in Irritable Bowel Syndrome (IBS) Symptom Severity Scale
Baseline
|
281.3 score on a scale
Standard Deviation 81.0
|
272.0 score on a scale
Standard Deviation 65.1
|
|
Change in Irritable Bowel Syndrome (IBS) Symptom Severity Scale
Week 5
|
209.3 score on a scale
Standard Deviation 81.8
|
194.7 score on a scale
Standard Deviation 79.1
|
SECONDARY outcome
Timeframe: Baseline, Week 5Population: Some participants who were randomized to an arm withdrew or were lost to follow up before receiving an intervention. The number of participants analyzed at each time point is based on a mITT analysis.
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.
Outcome measures
| Measure |
Rifaximin
n=36 Participants
Rifaximin 550 mg three times daily for 14 days
Rifaximin 550 MG: Rifaximin 550 mg three times daily for 14 days
|
Low FODMAP Group
n=29 Participants
Low FODMAP diet for 4 weeks
Low FODMAP Diet: Low FODMAP dietary intervention for 4 weeks
|
|---|---|---|
|
Change in Gastrointestinal System Ratings Scale (GSRS)
Baseline
|
52.0 score on a scale
Standard Deviation 13.2
|
52.1 score on a scale
Standard Deviation 13.3
|
|
Change in Gastrointestinal System Ratings Scale (GSRS)
Week 5
|
40.7 score on a scale
Standard Deviation 11.0
|
40.1 score on a scale
Standard Deviation 12.2
|
SECONDARY outcome
Timeframe: Baseline, Week 5Population: Some participants who were randomized to an arm withdrew or were lost to follow up before receiving an intervention. The number of participants analyzed at each time point is based on a mITT analysis.
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.
Outcome measures
| Measure |
Rifaximin
n=36 Participants
Rifaximin 550 mg three times daily for 14 days
Rifaximin 550 MG: Rifaximin 550 mg three times daily for 14 days
|
Low FODMAP Group
n=29 Participants
Low FODMAP diet for 4 weeks
Low FODMAP Diet: Low FODMAP dietary intervention for 4 weeks
|
|---|---|---|
|
Change in Stool Form
Baseline
|
5.6 score on a scale
Standard Deviation 0.8
|
5.6 score on a scale
Standard Deviation 0.8
|
|
Change in Stool Form
Week 5
|
5.0 score on a scale
Standard Deviation 1.1
|
5.3 score on a scale
Standard Deviation 0.9
|
SECONDARY outcome
Timeframe: Baseline, Week 5Population: Some participants who were randomized to an arm withdrew or were lost to follow up before receiving an intervention. The number of participants analyzed at each time point is based on a mITT analysis.
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.
Outcome measures
| Measure |
Rifaximin
n=36 Participants
Rifaximin 550 mg three times daily for 14 days
Rifaximin 550 MG: Rifaximin 550 mg three times daily for 14 days
|
Low FODMAP Group
n=29 Participants
Low FODMAP diet for 4 weeks
Low FODMAP Diet: Low FODMAP dietary intervention for 4 weeks
|
|---|---|---|
|
Change in Psychological Function
Baseline
|
8.6 score on a scale
Standard Deviation 6.5
|
8.3 score on a scale
Standard Deviation 6.2
|
|
Change in Psychological Function
Week 5
|
6.2 score on a scale
Standard Deviation 4.9
|
5.8 score on a scale
Standard Deviation 4.3
|
SECONDARY outcome
Timeframe: Baseline, Week 5Population: Some participants who were randomized to an arm withdrew or were lost to follow up before receiving an intervention. The number of participants analyzed at each time point is based on a mITT analysis.
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.
Outcome measures
| Measure |
Rifaximin
n=36 Participants
Rifaximin 550 mg three times daily for 14 days
Rifaximin 550 MG: Rifaximin 550 mg three times daily for 14 days
|
Low FODMAP Group
n=29 Participants
Low FODMAP diet for 4 weeks
Low FODMAP Diet: Low FODMAP dietary intervention for 4 weeks
|
|---|---|---|
|
Change in Irritable Bowel Syndrome Quality of Life Instrument (IBS-QOL)
Baseline
|
53.6 score on a scale
Standard Deviation 19.5
|
58.9 score on a scale
Standard Deviation 21.5
|
|
Change in Irritable Bowel Syndrome Quality of Life Instrument (IBS-QOL)
Week 5
|
62.6 score on a scale
Standard Deviation 20.4
|
67.8 score on a scale
Standard Deviation 18.5
|
SECONDARY outcome
Timeframe: Baseline, Week 5Population: Some participants who were randomized to an arm withdrew or were lost to follow up before receiving an intervention. The number of participants analyzed at each time point is based on a mITT analysis.
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.
Outcome measures
| Measure |
Rifaximin
n=36 Participants
Rifaximin 550 mg three times daily for 14 days
Rifaximin 550 MG: Rifaximin 550 mg three times daily for 14 days
|
Low FODMAP Group
n=29 Participants
Low FODMAP diet for 4 weeks
Low FODMAP Diet: Low FODMAP dietary intervention for 4 weeks
|
|---|---|---|
|
24-hour Diet Recall/Intake - Lactose
Baseline
|
4.1 grams per day
Standard Deviation 5.5
|
7.3 grams per day
Standard Deviation 9.6
|
|
24-hour Diet Recall/Intake - Lactose
Week 5
|
5.1 grams per day
Standard Deviation 6.7
|
1.4 grams per day
Standard Deviation 2.3
|
SECONDARY outcome
Timeframe: Baseline, Week 5Population: Some participants who were randomized to an arm withdrew or were lost to follow up before receiving an intervention. The number of participants analyzed at each time point is based on a mITT analysis.
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.
Outcome measures
| Measure |
Rifaximin
n=36 Participants
Rifaximin 550 mg three times daily for 14 days
Rifaximin 550 MG: Rifaximin 550 mg three times daily for 14 days
|
Low FODMAP Group
n=29 Participants
Low FODMAP diet for 4 weeks
Low FODMAP Diet: Low FODMAP dietary intervention for 4 weeks
|
|---|---|---|
|
24-hour Diet Recall/Intake - Gluten
Baseline
|
6.7 grams per day
Standard Deviation 6.0
|
5.7 grams per day
Standard Deviation 5.6
|
|
24-hour Diet Recall/Intake - Gluten
Week 5
|
7.2 grams per day
Standard Deviation 6.5
|
1.7 grams per day
Standard Deviation 4.2
|
OTHER_PRE_SPECIFIED outcome
Timeframe: 4 weeksGlucose breath tests (GBT) will be performed at baseline and repeated after intervention
Outcome measures
Outcome data not reported
OTHER_PRE_SPECIFIED outcome
Timeframe: 4 weeksChanges in fecal microbial diversity after intervention will be compared with baseline.
Outcome measures
Outcome data not reported
Adverse Events
Rifaximin
Low FODMAP Group
Serious adverse events
Adverse event data not reported
Other adverse events
| Measure |
Rifaximin
n=36 participants at risk
Rifaximin 550 mg three times daily for 14 days
Rifaximin 550 MG: Rifaximin 550 mg three times daily for 14 days
|
Low FODMAP Group
n=29 participants at risk
Low FODMAP diet for 4 weeks
Low FODMAP Diet: Low FODMAP dietary intervention for 4 weeks
|
|---|---|---|
|
General disorders
Dizziness/Light-headedness
|
2.8%
1/36 • 5 weeks
Some participants who were randomized to an arm withdrew or were lost to follow up before receiving an intervention. The number of participants analyzed is based on a mITT analysis.
|
0.00%
0/29 • 5 weeks
Some participants who were randomized to an arm withdrew or were lost to follow up before receiving an intervention. The number of participants analyzed is based on a mITT analysis.
|
|
Gastrointestinal disorders
Abdominal Pain and cramping
|
13.9%
5/36 • 5 weeks
Some participants who were randomized to an arm withdrew or were lost to follow up before receiving an intervention. The number of participants analyzed is based on a mITT analysis.
|
27.6%
8/29 • 5 weeks
Some participants who were randomized to an arm withdrew or were lost to follow up before receiving an intervention. The number of participants analyzed is based on a mITT analysis.
|
|
Gastrointestinal disorders
Bloating and gas
|
8.3%
3/36 • 5 weeks
Some participants who were randomized to an arm withdrew or were lost to follow up before receiving an intervention. The number of participants analyzed is based on a mITT analysis.
|
27.6%
8/29 • 5 weeks
Some participants who were randomized to an arm withdrew or were lost to follow up before receiving an intervention. The number of participants analyzed is based on a mITT analysis.
|
|
Gastrointestinal disorders
Heartburn
|
16.7%
6/36 • 5 weeks
Some participants who were randomized to an arm withdrew or were lost to follow up before receiving an intervention. The number of participants analyzed is based on a mITT analysis.
|
3.4%
1/29 • 5 weeks
Some participants who were randomized to an arm withdrew or were lost to follow up before receiving an intervention. The number of participants analyzed is based on a mITT analysis.
|
|
Gastrointestinal disorders
Nausea
|
13.9%
5/36 • 5 weeks
Some participants who were randomized to an arm withdrew or were lost to follow up before receiving an intervention. The number of participants analyzed is based on a mITT analysis.
|
6.9%
2/29 • 5 weeks
Some participants who were randomized to an arm withdrew or were lost to follow up before receiving an intervention. The number of participants analyzed is based on a mITT analysis.
|
|
Gastrointestinal disorders
Diarrhea
|
0.00%
0/36 • 5 weeks
Some participants who were randomized to an arm withdrew or were lost to follow up before receiving an intervention. The number of participants analyzed is based on a mITT analysis.
|
17.2%
5/29 • 5 weeks
Some participants who were randomized to an arm withdrew or were lost to follow up before receiving an intervention. The number of participants analyzed is based on a mITT analysis.
|
|
Gastrointestinal disorders
Constipation
|
2.8%
1/36 • 5 weeks
Some participants who were randomized to an arm withdrew or were lost to follow up before receiving an intervention. The number of participants analyzed is based on a mITT analysis.
|
6.9%
2/29 • 5 weeks
Some participants who were randomized to an arm withdrew or were lost to follow up before receiving an intervention. The number of participants analyzed is based on a mITT analysis.
|
|
General disorders
Headache
|
5.6%
2/36 • 5 weeks
Some participants who were randomized to an arm withdrew or were lost to follow up before receiving an intervention. The number of participants analyzed is based on a mITT analysis.
|
0.00%
0/29 • 5 weeks
Some participants who were randomized to an arm withdrew or were lost to follow up before receiving an intervention. The number of participants analyzed is based on a mITT analysis.
|
|
Gastrointestinal disorders
Belching
|
2.8%
1/36 • 5 weeks
Some participants who were randomized to an arm withdrew or were lost to follow up before receiving an intervention. The number of participants analyzed is based on a mITT analysis.
|
0.00%
0/29 • 5 weeks
Some participants who were randomized to an arm withdrew or were lost to follow up before receiving an intervention. The number of participants analyzed is based on a mITT analysis.
|
|
Renal and urinary disorders
Increased urination
|
2.8%
1/36 • 5 weeks
Some participants who were randomized to an arm withdrew or were lost to follow up before receiving an intervention. The number of participants analyzed is based on a mITT analysis.
|
0.00%
0/29 • 5 weeks
Some participants who were randomized to an arm withdrew or were lost to follow up before receiving an intervention. The number of participants analyzed is based on a mITT analysis.
|
|
Skin and subcutaneous tissue disorders
Easily sunburned
|
2.8%
1/36 • 5 weeks
Some participants who were randomized to an arm withdrew or were lost to follow up before receiving an intervention. The number of participants analyzed is based on a mITT analysis.
|
0.00%
0/29 • 5 weeks
Some participants who were randomized to an arm withdrew or were lost to follow up before receiving an intervention. The number of participants analyzed is based on a mITT analysis.
|
|
General disorders
Fatigue
|
2.8%
1/36 • 5 weeks
Some participants who were randomized to an arm withdrew or were lost to follow up before receiving an intervention. The number of participants analyzed is based on a mITT analysis.
|
0.00%
0/29 • 5 weeks
Some participants who were randomized to an arm withdrew or were lost to follow up before receiving an intervention. The number of participants analyzed is based on a mITT analysis.
|
|
General disorders
Swelling
|
2.8%
1/36 • 5 weeks
Some participants who were randomized to an arm withdrew or were lost to follow up before receiving an intervention. The number of participants analyzed is based on a mITT analysis.
|
0.00%
0/29 • 5 weeks
Some participants who were randomized to an arm withdrew or were lost to follow up before receiving an intervention. The number of participants analyzed is based on a mITT analysis.
|
|
Eye disorders
Blurry Vision
|
2.8%
1/36 • 5 weeks
Some participants who were randomized to an arm withdrew or were lost to follow up before receiving an intervention. The number of participants analyzed is based on a mITT analysis.
|
0.00%
0/29 • 5 weeks
Some participants who were randomized to an arm withdrew or were lost to follow up before receiving an intervention. The number of participants analyzed is based on a mITT analysis.
|
|
Gastrointestinal disorders
Mucus in Stool
|
2.8%
1/36 • 5 weeks
Some participants who were randomized to an arm withdrew or were lost to follow up before receiving an intervention. The number of participants analyzed is based on a mITT analysis.
|
0.00%
0/29 • 5 weeks
Some participants who were randomized to an arm withdrew or were lost to follow up before receiving an intervention. The number of participants analyzed is based on a mITT analysis.
|
Additional Information
Results disclosure agreements
- Principal investigator is a sponsor employee
- Publication restrictions are in place