Quantitative analysis of adipose tissue for predicting Crohn's disease postoperative endoscopic recurrence and anastomotic ulcer

Objective: Inflammation and ulcers at the anastomotic site are frequently observed after intestinal resection surgery for Crohn's disease (CD), which often signify postoperative recurrence. Crohn's disease causes abnormalities in whole-body fat metabolism, and alterations in subcutaneous and visceral fat are potential indicators of disease development. This study aimed to quantify the areas of subcutaneous (SFA) and visceral fat (VFA) and investigate the relationship between fat tissue and endoscopic recurrence and anastomotic ulceration after Crohn's disease surgery.

Methods: We conducted a retrospective analysis of clinical data from 279 patients diagnosed with Crohn's disease. Using abdominal CT (Computed Tomography) scans at the level of the umbilicus, we measured the area of subcutaneous and visceral fat, and calculated the Mesenteric Fat Index (MFI), which is defined as the ratio of the area of visceral fat to subcutaneous fat. We compared the changes in fat tissue between surgical Crohn's disease patients and non-surgical patients in remission, as well as changes in fat tissue before and after surgery, and between patients with and without endoscopic recurrence after surgery.

Results: The MFI value of the surgical group was higher than that of the non-surgical group(0.88(1.27 ± 1.26) VS 0.39(0.44 ± 0.21), P < 0.001), while the SFA value was lower(70.16(92.97 ± 78.23) VS 157.64(175.96 ± 101.58), P < 0.001). Of the 134 surgical patients who underwent abdominal CT examination after surgery, the SFA value was significantly higher after surgery(143.61 ± 81.86 VS 90.87 ± 71.93, P < 0.001), and the MFI value decreased accordingly(0.57 ± 0.36 VS 1.30 ± 1.35, P < 0.001). Multivariate Cox analysis indicated that high VFA and MFI values, smoking history, and preoperative biologic therapy were all risk factors for postoperative endoscopic recurrence(p < 0.05), while high MFI values and preoperative biologic therapy were also risk factors for anastomotic ulcers(p < 0.05). The Kaplan-Meier analysis showed that these factors increased the risk of reaching the endpoint with time(p < 0.05). The ROC curve results showed that MFI value had high diagnostic value for postoperative endoscopic recurrence [AUC:0.831, 95% CI: 0.75-0.91, p < 0.001] and anastomotic ulcers [AUC:0.801, 95% CI: 0.71-0.89, p < 0.001].

Conclusions: Surgical CD patients have significantly higher MFI values but the values decline after surgery. When the preoperative MFI value is > 0.82, the risk of postoperative endoscopic recurrence increases significantly, and when the MFI value is ≥ 1.10, the risk of anastomotic ulceration after surgery increases significantly. Meanwhile, biologic therapy preoperatively also is a high-risk factor for early postoperative endoscopic recurrence or anastomotic ulcers after intestinal resection surgery.