P216 Mesenteric disease is directly related to mucosal disease in Crohn's disease

Abstract

Background: Crohn's disease (CD) displays mesenteric disease manifestations such as fat wrapping and mesenteric thickening. The frequency at which these occur in CD point to a pathobiological relevance. Fat wrapping in particular has been suggested to play a role in disease progression [1]. This study aimed to evaluate the relationship between mesenteric disease and other manifestations of CD and to examine the significance of advanced mesenteric disease. Methods: Ethical approval and informed consent were obtained from the HSE Mid-Western Regional Hospital Research Ethics Committee. All patients undergoing resection for ileocolic CD in University Hospital Limerick since 2010 have undergone a resection which included the mesentery. Novel disease activity indices were generated to quantify mesenteric and mucosal disease. Mesenteric disease was graded based on the presence and extent of mesenteric thickening and fat wrapping (Table 1A). Mucosal disease was graded based on the presence of different intestinal features of CD (Table 1B). Pre-operative Crohn's disease activity index (CDAI) was recorded for all patients. The effect of smoking on all disease activity indices was investigated. The relationship between histologic fat wrapping and surgical recurrence was determined in all intestinal forms of CD (n=94). Table 1A. Mesenteric disease activity index in Crohn's disease Key: FW = fat wrapping, MT = mesenteric thickening. Table 1B. Mucosal disease activity index in Crohn's disease Results: Mucosal and mesenteric disease were topographically coupled in all resection specimens examined. There was a direct association between mesenteric and mucosal disease when investigated using the novel disease activity indices (r=0.78, p<0.0001). Higher CDAI scores were associated with higher mesenteric and mucosal disease scores (r=0.72; r=0.70, respectively, p<0.0001). Patients who smoked had more severe mesenteric disease (p<0.05) but there was no effect on mucosal disease or CDAI. Fat wrapping was observed histologically in 13 (41.9%) index resection specimens and 18 (72%) recurrence specimens. Fat wrapping was an independent predictor of increased risk of surgical recurrence (HR 4.7, 95% CI: 1.71–13.01, p=0.003) and was also associated with a shortened time to recurrence (p<0.001). Conclusions: There was a direct association between mesenteric disease and mucosal disease manifestations. Fat wrapping independently predicted surgical recurrence and was associated with a shortened time to recurrence.