The Diagnostic Predictability of Food Allergy Testing

A variety of methods are available to assess food items that an individual with IBS may not tolerate well. No study has compared the predictability of each method to the results of an Elimination/Challenge (E/C) diet in individuals suffering from IBS and, or assessed which method might more accurately identify Non Immune Mediated Food Allergies (NIMFAs) in IBS suffers' An understanding of the relative agreement between these tests may help patients and practitioners make better decisions around how to best investigate NIMFAs for IBS and inform the design of larger studies on this topic.

The primary objective of this study is to determine the ability of each different laboratory method of food testing (IgG titres, Cytotoxic assay and electrodermal screening methods) for food reactivity to predict those foods that an individual with IBS reacts as assessed via an elimination diet in an adult population diagnosed with IBS by ROME III criteria and a score of greater than 200 on the IBS Severity Scoring System.

The secondary objective is determine inter-method agreement, at the individual level, between the sensitivity of food identified via each laboratory method, overall and according to severity of the reaction (high, medium, low, and no reaction).

The third objective is to measure the impact of the elimination of possible food allergies on the symptoms of IBS in the participants.

The fourth objective is to determine whether intestinal permeability maybe contributing to the symptomatology of IBS as assessed via an intestinal permeability test.

The fifth objective is to determine whether, after a period of eliminating potentially reactive foods, this provides some healing benefit to the gastrointestinal tract.

1. Study Design

This correlative and hypothesis generating pilot study is to be conducted at a single investigational site. This study will be open to members of the public, staff, and students of Canadian College of Naturopathic Medicine (CCNM) and patients of the Robert Schad Naturopathic clinic (RSNC) who suffer from IBS. The study will be conducted at CCNM in the Integrated Health Center (IHC).

Individuals who are interested in participating will be screened by two naturopathic doctors for their suitability. The screening process involves an assessment of the inclusion and exclusion criteria, confirmation of symptoms of IBS and of their ability to commit to and follow through on dietary restrictions. A second meeting with another member of the study team will also occur. Team members will confer and agree upon all study participants selected. The study participants will be contacted by phone and invited to participate in the study. The first visit will be scheduled at this time and a copy of the E/C diet guidelines emailed to the individual.

At the first visit, study participants will complete the Study Case Report, provide the necessary blood samples for the laboratory tests, undergo the electrodermal screening for food allergies, complete necessary symptoms tracking forms and provided with an intestinal permeability test to complete at home prior to initiating the elimination phase of the study. The E/C diet guidelines will be reviewed and any questions answered.

Study participants will be contacted by telephone during week 2 of the study by a member of the study team to address any dietary questions that may have arisen during the first week of the elimination diet.

Subjects will return to the clinic at weeks 3, 5, 7 and 9 for completion of the validated questionnaires, review of study diary, query of adverse events, and compliance monitoring.

At visit 3 (week 5), study participants will also receive the list of food items that will be introduced during the challenge portion of the study. The study participants will be provided with a second intestinal permeability test to complete at home prior to initiating the challenge phase of the study.

The study participants and study team members will remain blinded to the results of the all tests until the completion of the study.

The primary endpoint of the study is the degree of agreement between the food items identified as eliciting a reaction through an elimination/challenge diet versus those food items identified through laboratory testing. Cohen's kappa will be the statistical measure to assess agreement.

The secondary endpoint of the study is the degree of inter-laboratory agreement of reactionary food items across all of the methods (laboratory and electrodermal screening) used in the study. Cohen's kappa will be the statistical measure to assess agreement.

The third endpoint of the study is the change in the scores on the irritable bowel severity scoring system and FAST symptom checklist between the end of the elimination diet phase and baseline (start of the study). The irritable bowel severity scoring system is a validated questionnaire used to monitor irritable bowel syndrome. This scoring system incorporates measures of pain, distension and bloating due to gas, bowel dysfunction (constipation and diarrhea) and quality of life/global well being and has been validated as a reproducible and sensitive means of measuring symptoms associated with IBS.

A numerical scale, from 0 to 10 will be used as a measure of symptom severity on the FAST Study Diet \& Symptoms Diary tracking forms.

The FAST symptom checklist was documented by Dick Thom, a naturopathic doctor, in his book "Coping with Food Intolerances: Surviving the nineties." This checklist serves as a quick and easy method for study participants to note the symptoms that they are experiencing and their severity according to a rating scale provided on the checklist.

Study Duration Upon successful screening, washout period (if necessary), study participants will participate for the full 9 week active treatment duration. At baseline (week 1), study participants will complete validated IBS symptom questionnaire, the FAST Study Symptom checklist, blood samples will be taken for the necessary food allergy testing and electrodermal screening will be performed. Study participants will return to the clinic at weeks 3, and 5, 7, and 9 to complete the validated IBS symptom questionnaire and FAST Study Symptom checklist. During all study visits, study participants are queried for adverse events, study diaries will be reviewed, and compliance will be monitored via diet diary. Study participants will also be re-queried for compliance with the exclusion criteria of the protocol primarily with respect to confounding factors such as new medications, or natural health products. Study visits 3 through 7 are expected to take approximately 30 minutes. The first visit will take 1.5 hours and the final visit 45 minutes.