P457 Small bowel involvement proximal to the terminal ileum is a major risk factor for intestinal resection in patients with small bowel Crohn’s disease

Abstract

Abstract Background The current Montreal classification categorizes Crohn's disease (CD) with small bowel involvement into two groups: L1 and L3. The study aimed to investigate the significance of small bowel involvement proximal to the terminal ileum as a significant risk factor for intestinal resection. Methods We conducted a retrospective review of the medical records of Crohn's disease patients diagnosed between January 2001 and December 2020 at Seoul St. Mary's Hospital, St. Vincent Hospital, and Eunpyeong St. Mary's Hospital. The extent of small bowel involvement was independently assessed by two experienced gastrointestinal radiologists using conventional CT, CT enterography, or MR enterography at the time of diagnosis. The terminal ileum was defined as the distal ileal segment within 10 cm from the ileocecal valve and the jejunum was defined as the proximal 1/2 of the small intestine beyond the ligament of Treitz. Radiologic disease activity and fibrostenosis at the time of diagnosis were also scored as 0, 1, and 2 using Maglinte classification, respectively. Results Out of 617 CD patients, 346 were included in the study, while 271 were excluded due to radiologic noninvolvement of the small bowel, inadequate or missing radiologic data, initial diagnosis made at another institution, or diagnosis through surgery. Median age at diagnosis was 24 years (range 10-76) and 250 (72.3%) were male. The median follow-up duration was 53 months (4-201). During the follow-up period, 43 patients (12.4%) underwent intestinal resection. Small bowel involvement proximal to the terminal ileum was significantly associated with a higher cumulative risk of intestinal resection (15.4% vs. 3.5%, P=0.006). Neither jejunal involvement or colonic involvement (L3 vs. L1) showed a significant association with cumulative risk of intestinal resection (16.0% vs. 11.1%, P=0.222; 12.4% vs. 12.4%, P=0.773). Radiologic disease activity and fibrostenotic score at the time of diagnosis were significantly associated with the cumulative risk of intestinal resection, respectively (0% vs. 4.4% vs. 19.7%, P<0.001; 8.5% vs. 16.7% vs. 28.2%, P<0.001). Conclusion Small bowel involvement proximal to the terminal ileum was a major risk factor for requiring intestinal resection in patients with small bowel CD, while jejunal involvement was not. These findings suggest a need for subclassifying small bowel CD.