LAUSR

Background Restorative proctocolectomy is a surgical option in patients with ulcerative colitis who become refractory to medical therapy. Various studies have implicated SCFA in both the development of IBD and flares of IBD. Furthermore, it has been shown that SCFA concentrations are significantly lower in faecal samples from patients with pouchitis when compared with healthy controls. Our study aimed to assess longitudinal changes in SCFA that occur in a pouch to determine if they can predict or are associated with the development of pouchitis. To date no study has analysed short chain fatty acids in mucosal biopsy tissue from these patients. Methods Patients who underwent restorative proctocolectomy at a single centre underwent pouchoscopy at the time of restoration of continuity and then every 6 months for a year. Biopsies were retrieved from the pouch body. Pouchitis was defined using the pouch disease activity index. The development of pouchitis was assessed at 6 and 12 months.SCFA were measured using an Agilent 7000C Triple Quadrupole GC/MS-MS System. Simca was used for multivariate analysis and T-tests were used for univariate analysis. Results There were 56 biopsy samples. There were 22 patients (17 males); 16 UC and 6 FAP patients. Median age of the cohort was 40 years (range 20–60 years). Of the UC patients four developed pouchitis within one year. Comparing UC patients at the time of closure of ileostomy, there were significant decreases in caproic acid (4674uM vs 12217uM p<0.01), valeric acid (1580uM vs 3695uM p=0.01), isovolaric acid (721uM vs 2940uM p=0.05), isobutyric acid 35072uM vs 76074uM p=0.03) and lactic acid (1580uM vs 3732uM p=0.02) between those who developed pouchitis within a year and those who did not develop pouchitis at 1 year. Conclusions A decrease in SCFA found in the mucosal tissue at time of closure of ileostomy may predict onset of pouchitis within a year. This study is the first to demonstrate that SCFA can be analysed from biopsies. Future studies need to determine factors that may contribute to tissue SCFA levels which may help reduce the incidence of pouchitis.