Prevalence of Antihistamine Responsive Irritable Bowel Syndrome With Diarrhea

Study Overview
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Brief Summary
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Irritable bowel syndrome is a functional disorder of the gastrointestinal tract diagnosed with the Rome criteria. The Rome IV criteria are based on abdominal pain symptoms and stool habits including stool frequency and stool forms [1]. They define 3 main subtypes based on symptoms: 1) IBS with diarrhea; 2) IBS with constipation: and 3) mixed symptoms of constipation and diarrhea. The IBS with diarrhea (IBS-D) subtype has the highest prevalence. Currently, treatment of IBS-D includes antidiarrheals, bile acid sequestrants, antispasmodics, tricyclic antidepressants, and FODMAP diet. However, many patients are intolerant or unresponsive to the above treatments. Outside of IBS, chronic diarrhea affects about 5% of adults. We have described a syndrome in a subset of IBS patients presenting with post prandial diarrhea, flushing and dermatographia whose symptoms are prevented by pre-treatment with combined H1 and H2 antihistamines [2]. However, the prevalence of this syndrome among the IBS + D patients is not known nor have the clinical characteristics or predictors of antihistamine responsive IBS + D been defined.

Detailed Description
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We have published a series of 5 patients with chronic post prandial diarrhea (PPD) that begins within 3 hours after eating, associated with dermatographia, responsive to antihistamines [2]. In these cases, no underlying causes were identified to explain PPD; diagnoses of food allergy, lactose intolerance, celiac disease, dumping syndromes, inflammatory bowel disease, systemic mastocytosis were excluded. Patients with the syndrome have prior histories of chronic urticaria and experience associated transient symptoms of flushing, headache, tachycardia, and abdominal bloating during PPD episodes. This syndrome, except for our published report, have not been previously described in the medical literature. Patients with systemic mastocytosis and mast cell activation syndrome experience PPD but along with anaphylactic manifestations (e.g. wheezing, hypotension) and measurable mast cell biomarkers are identifiable in affected patients (i.e. serum mast cell tryptase or 24 hour urine methylhistamine, PGF2a). Therefore, it is important to characterize PPD responsive to antihistamines in a general GI patient population and to publish our findings. The impact on human health will be substantial; we found that these patients are undiagnosed and untreated for many years. Our aim is to recruit 50-100 patients from the UC Health affiliated gastroenterology clinics with access UC health which has 300-500 potential subjects. We would need to recruit 10-20% percentage of these potential subjects. Kris Ramprasad MD, a faculty member in the Division of Gastroenterology, David Bernstein MD, a faculty member in the Division of Allergy and Rheumatology, allergy fellows and GI fellows will direct and implement subject screening and consenting.

Official Title
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Observational Study of the Prevalence of Antihistamine Responsive Gastrointestinal Symptoms in Patients Diagnosed With Irritable Bowel Syndrome With Diarrhea

Conditions
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Irritable Bowel Syndrome, Dermatographism, Post-prandial Diarrhea

Intervention / Treatment
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* Drug: Antihistamine


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age 18 years and older Prior to Diagnosis of IBS + diarrhea based on ICD 10 codes with or without constipation unresponsive to prior treatments Moderate to severe symptom severity score (>175 points) based on IBS symptom severity scale Seeking evaluation by a health care professional Negative serologic celiac panel No response to lactose elimination diet by history Normal colonoscopy Able to complete symptoms diaries and global evaluations Exclusion Criteria: Confirmed IgE dependent food allergy as a cause of the gastrointestinal symptoms. Lactose intolerance by history Celiac disease by serology Inflammatory bowel disease or colitis Bile acid diarrhea by history Post-surgical GI symptoms (e.g., dumping syndrome) by history No colonoscopy performed GI malabsorption Current pregnancy Current severe depression or history of psychosis Current treatment with tricyclic antidepressants

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| IBS-D + dermatographism<br>IBS-D patients with dermatographism. Cetirizine 10 mg and famotidine 20 mg will be dispensed to each patient, to be taken twice a day at 6-9AM one hour before eating breakfast and again at evening 12 hours after the morning dose for 30 days | Drug: Antihistamine<br>* Cetirizine 10 mg and famotidine 20 mg will be dispensed to each patient, to be taken twice a day at 6-9AM one hour before eating breakfast and again at evening 12 hours after the morning dose for 30 days<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| IBS symptomy severity score | ≥50 point in reduction of symptoms with antihistamines based on the IBS symptom severity scale (IBS-SSS). This validated scale contains 5 questions that measures on a 100 point scale (for a total of 500 points) the severity of abdominal pain, frequency of abdominal pain, severity of abdominal distension, dissatisfaction with bowel habits, and interference with quality of life. | 135 days | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| IBS quality of life | ≥10 point improvement in Quality of Life (IBS-QOL) questionnaire and a moderately improved or substantially improved on the IBS global assessment of improvement (IBS-GAI) scale. The IBS-QOL is a 34-item questionnaire which assesses the degree to which IBS interferes with the patient's quality of life. The IBS-GAI asks one question that assesses the overall improvement in symptoms in the past 7 days. | 135 days | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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IBS, irritable bowel syndrome, Dermatographism, post-prandial diarrhea, antihistamine