Endoscopic Relapse Risk Factors After Ileocolic Resection on Crohn's Disease Patients in the Biologic Era

Crohn's disease is a chronic inflammatory bowel disease whose preferential location is the ileo-colon, for which surgical management is necessary in 60% of patients.

The most common surgical procedure is ileo-caecal resection for symptomatic last ileal loop stenosis resistant to a well conducted medical treatment.

The conventional surgical technique aims to preserve the length of the digestive tract as much as possible. From a technical point of view, the resection passes as close as possible to the small intestine, leaving the vessels within the mesentery in place.

Despite the improvement of therapeutics (over the last decade, 80% of patients present an endoscopic recurrence at 1 year after surgery. Endoscopic recurrence is defined as the apparition of new typical mucosal lesions based on the Rutgeerts classification.

According to the last ECCO guidelines, biologic agents (TNF-inhibitors, ustekinumab and vedolizumab) are used as maintenance treatment in moderate-to-severe Crohn's disease patients:

• who achieved remission with anti-TNF agents -> maintenance treatment using the same treatment.
• who have achieved long-term remission with the combination of infliximab and immunosuppressants -> monotherapy with infliximab.
• who have achieved long-term remission with the combination of adalimumab and immunosuppressants -> monotherapy with adalimumab. The risk factors for postoperative recurrence are now well established and include smoking habit, penetrating or fistulizing phenotype (classified as B3 in the Montréal classification), perineal disease, history of previous bowel resection, extensive small bowel resection (>20 cm).

Recently, the role of the mesentery in Crohn's disease has been deeply investigated. There is a mesenteric nerve dysfunction with inhibition of anti-inflammatory activity, a major angiogenesis, a multiplication of lymphatic vessels with emboli at the origin of lymphatic drainage abnormalities, a mesenteric hypertrophy with multiple small adipocytes secreting adipokines.

These new elements have raised the question of a potential benefit of a combined resection of the mesentery during an ileocecal resection in the treatment of Crohn's disease.

CALVIN J Coffrey et al. carried out a study in 2008 comparing a prospective cohort with ileo-caecal resection including the mesentery (mesentery resection group) to a retrospective cohort with classical ileocecal resections (ICR group). The results were very promising in terms of recurrence requiring surgical management with a re-operation rate at 5 years of 40% in the classical ICR group vs 2.9% in the mesenteric resection group. And shows that significant mesenteric disease is an independent risk factor for recurrence with a HR=4.7 (p<0.007).

Thus, it is necessary to analyse within local patient base: the percentage of endoscopic recurrence at 6 months after surgery in patients treated with anti TNFa as well as the risk factors at the origin of the increase of these recurrences, more particularly the anatomopathological factors which could call into question the surgical practices within the long term a major interest in resection of the mesentery.

Therefore, the investigator carried out a retrospective study in two referral tertiary center, Montpellier University Hospital and Nîmes University Hospital. The investigator prospectively collected data from 2014 to 2022 from Crohn's disease patients treated with TNF inhibitors who have undergone ileocolic resection, to determine the percentage of endoscopic recurrence at 6 months and its risk factors.