Targeted Food Elimination for Treatment of Functional Gastrointestinal Diseases in Children (FGID)

Randomized Controlled Trial of Food Elimination Based on IgG Antibodies for Treatment of Functional Gastrointestinal Diseases (FGIDs) in Children

Recurrent Abdominal Pain (RAP) in children is common and causes significant functional impairment and poor quality of life. Lifestyle factors such as diet, anxiety, and stress are important triggers of abdominal pains, but there is lack of high quality research evidence on optimal treatment modalities in children. This study aims to evaluate the effect of food elimination on abdominal pain frequency and severity in a cohort of children with abdominal pain associated Functional Gastrointestinal Diseases (FGID). The primary outcome will be a comparison of abdominal pain frequency and severity between standard therapy and targeted food elimination, based on IgG antibody results to a multiple food antigen panel. The investigators anticipate that 'targeted dietary elimination' as a treatment strategy will resolve abdominal pain and improve quality of life in children.

Randomized controlled single center trial. Setting: Outpatient pediatric gastroenterology (PG) clinic, Children's Hospital, London, Canada. Methodology: After a 4 week run in period, 60 children aged 5-18 years, meeting Rome 3 inclusion criteria for abdominal pain associated FGID will be recruited to the trial. After informed consent, the participants will be randomized to either a standard treatment or lifestyle modification (dietary elimination) group in the ratio of 1:1. IgG testing to food antigens will be completed in both groups using a commercially available specific IgG ELISA-based multiple food allergen panel but will ONLY be disclosed for the lifestyle modification group. The patient will receive specific advice by a dietitian to exclude a maximum of two food items from his/her diet for 4 weeks. Children will be followed-up in PG clinic at 4-weekly intervals for 16 weeks. At every clinic visit, Diary of food intake, Abdominal Pain Index (API) and Quality of Life (QOL) questionnaire will be completed by both child and parent. The standard therapy group will receive conventional treatment for Abdominal Pain (AP) as per usual practice at the PG Clinic. Response is defined as more than 50% improvement in frequency and severity of abdominal pain. At each follow up visit, non-responders will cross over to the other arm of the study. At the end of the trial, non-responders in either group will continue to receive conventional treatment in the PG Clinic. Responders will be discharged back to their family physicians. Data will be analyzed using IBM SPSS Statistics, version 22.0.

In the lifestyle modification group, where specific IgG antibodies to foods are identified, the intervention is appropriate dietary elimination. The IgG antibody results will be disclosed and specific dietary elimination advice will be provided by an experienced dietician; provide diet alternatives to prevent nutritional deficiencies and improve adherence to diet. To improve compliance, a maximum of 2 high IgG positive foods will be eliminated at any one time in each 4 week period. Children will be followed-up in PG clinic at 4-weekly intervals for 16 weeks. Response is defined as more than 50% improvement in frequency and severity of abdominal pain. They will be assessed at visits 2, 3, 4 and 5 for follow-up, and non-responders, will cross over to the other arm of the study.

The standard therapy group will not receive results of IgG antibody testing. The patients will receive conventional treatment for Abdominal Pain as per usual practice at the Pediatric GI (PG) Clinic - counseling, reassurance, improving coping strategies and pain relief as appropriate. Children will be followed-up in PG clinic at 4-weekly intervals for 16 weeks. Response is defined as more than 50% improvement in frequency and severity of abdominal pain. They will be assessed at visits 2, 3, 4 and 5 for follow-up, and non-responders, will cross over to the other arm of the study.

The IgG antibody results will be disclosed ONLY to the patients in the lifestyle modification group by phone approximately one week after clinic visit.. 'Dietary Exclusion' will be advised by a dietitian. Patients are advised to eliminate a maximum of two foods as identified by high IgG antibody titres.

The standard therapy group will receive conventional treatment for Abdominal Pain as per usual practice at the Pediatric GI (PG) Clinic - counseling, reassurance, improving coping strategies and pain relievers as appropriate.

Primary Outcome: The Abdominal Pain (AP) frequency and severity is calculated in each clinic visit using a 4 point questionnaire - the validated Abdominal Pain Index (API): Child Form and Parent Proxy form for age range 8 to 18 years. For age range 5 to 7 years, only the Abdominal Pain Index: Parent proxy form will be used. The 4 point scale measures the frequency of abdominal pain (Scores range 0-none to 5-every day and constant), duration of abdominal pain (scores range 0-no pain to 5-all day) and severity of abdominal pain (scores range from 0-no pain to 10-most pain). Improvement in AP is defined as >50% reduction in frequency and severity of AP in food elimination and standard treatment groups.

The KINDL Questionnaire: self report and parent proxy versions will be used for different age groups. The KINDL questionnaire consists of 24 Likert-scaled items associated with six dimensions:physical well-being, emotional well-being, self-esteem, family, friends and everyday functioning (school or nursery school/kindergarten). The sub-scales of these six dimensions can be combined to produce a total score.

Compliance with dietary exclusion in dietary exclusion group at visits 3, 4 and 5. Compliance with conventional treatment in standard group at visits 3, 4 and 5. Adherence to advice and treatment will be measured by clinician impression at visits in both groups. (measured by consistency of completion of diaries and patient reporting of adherence to medical advice).

Inclusion Criteria: Children 5-18 years of age with a diagnosis of Abdominal Pain-related FGIDs (Functional Abdominal Pain , FAP syndrome, Functional Dyspepsia, Irritable Bowel Syndrome, Abdominal Migraine) as defined by the Rome 3 criteria. Acquisition of informed consent Exclusion Criteria: Children less than 5 years of age Organic cause of abdominal pain established by investigations (e.g. Crohn's disease) Diagnosis of failure-to-thrive or co-morbid chronic physical disease (e.g., Diabetes) Any medical condition that in the opinion of the investigator would be unsafe for trial participation. Lack of follow-up or failure to comply with study procedures.

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