Preventing postoperative relapse of Crohn's disease by using IgG4 guided exclusion diets

INTERVENTION: This will be a randomised controlled study. Patients will be enrolled for the study preoperatively. Patients will be invited to participate at the first available opportunity following the decision to perform surgery. The discussion could be held in the hospital wards in case of urgent surgeries and outpatient clinics for those undergoing elective procedure. Results from routine pre operative checks including BMI, CRP levels, Hemoglobin level, WBC count, platelet count, prealbumin, Albumin levels and faecal calprotectin levels will be collected. An additional 10 ml of blood will be collected at the same venepuncture for IgG4 titers. The sample will be centrifuged and stored at ‐40o C and processed in batches of four. IgG4 levels against 14 common food antigens will be checked using fluoroenzymeimmunoassay. Modified CDAI questionnaire will also be completed at enrolment. They will be randomized into intervention group and control (normal diet) group by simple randomization. Four food antigens (and hence food types) against which each patient had the highest titres will be identified. Patients in the intervention group will be apprised of the IgG4 titres prior to discharge and appropriate written advice on food to be excluded will be given. Exclusion diet will be commenced 1 month after surgery. Patients in control group will continue to have normal diet. No changes to their drug maintenance regimen will be made. As a routine, all postoperative patients with Crohn's disease are followed up in the clinic every 3 months. On each routine follow up, they undergo clinical examination including BMI and laboratory tests. Laboratory tests include Hemoglobin levels, WBC count, platelet count, albumin levels, pre albumin levels, CRP levels, liver function tests, renal function tests and faecal calprotectin levels. In addition, they undergo colonoscopy at one year. For the purpose of the study, results from the routine assessments including BMI, Hemoglobin, CRP levels, P CONDITION: Crohn's disease ; Digestive System ; Crohn disease, unspecified PRIMARY OUTCOME: 1. Relapse over a 1 year period defined by Rutgeerts endoscopic severity score of i2, i3 or i4; 2. Crohn's Disease Activity Index (CDAI) >150 or CDAI increase of more than 100 over baseline ; 3. Need for therapy to induce remission SECONDARY OUTCOME: Improvement in quality of life, measured by Short Inflammatory Bowel Disease Questionnaire (SIBDQ) INCLUSION CRITERIA: 1. Patients with histological diagnosis of Crohn's disease 2. Patients who needed surgery for Crohn's disease 3. Patients who agreed to dietary therapy for a minimum of 1 year or until relapse 4. Patients aged 16 and over 5. Patients capable of providing informed consent