The operative risk and natural history after the diagnosis of ileal penetrating Crohn's disease.

Background and Purpose: Crohn's disease (CD) is marked by transmural inflammation of the bowel wall leading to stricturing and/or penetrating complications in the majority of patients. The natural history and operative risk after the diagnosis of an ileal penetrating complication is understudied. The aim was to study the disease course and need for surgery in patients diagnosed with a penetrating ileal CD complication and to assess the risk factors associated with worse postoperative outcome.
Patients and Methods: In this cohort study, all cross-sectional imaging exams (computed tomography and/or magnetic resonance imaging) performed between 2006 and 2014 in patients with CD in a tertiary referral centre were reviewed for the presence of ileal penetrating complications (defined as abscesses, phlegmones and/or fistula). Demographic, clinical, biochemical, radiological and endoscopic factors were assessed retrospectively in these patients as well as the need for surgery (intestinal resection and/or strictureplasties) and postoperative complications.
Results: In total, 1803 cross-sectional imaging exams in 957 CD patients were performed during the study period. In 113 patients, penetrating ileal CD complications were identified. The majority of these patients were referred for surgery (86%) (median time to surgery 1 month, interquartile range: 1-4.9 months). In multivariate analysis, only the presence of abscesses was associated with subsequent surgery (P=0.034; hazard ratio=1.65; 95% confidence interval: 1.04-2.61). Severe postoperative complications (Dindo-Clavien>II) were present in 13% of the patients. Albumin less than 32 g/l was associated with a five-fold increase in severe complications (P=0.039; hazard ratio=4.9; 95% confidence interval: 1-22). Up to 35% of the patients needed no further medical treatment during the first 5 years postoperatively.
Conclusion: In this cohort, the majority of patients with penetrating ileal CD underwent surgery. The presence of an abscess showed a significant association with the need for surgery. There was an acceptable postoperative complication rate. Patients with low albumin had an unfavourable postoperative course. The long-term outcome after surgery was favourable.