Superior predictive value of transmural over endoscopic severity for colectomy risk in ulcerative colitis: a multicenter prospective cohort study

Endoscopic activity is associated with an increased risk of surgery in patients with ulcerative colitis (UC). Transmural activity, as defined by Milan Ultrasound Criteria (MUC) >6.2, reliably detects endoscopic activity in patients with UC. The study aimed to assess in UC patients whether transmural severity is a better predictor of colectomy as compared to endoscopy.Consecutive adult UC patients were recruited in two IBD Referral Centers and underwent colonoscopy and intestinal ultrasound in a blinded fashion. The need for colectomy was assessed at follow-up. Univariable and multivariable logistic and Cox regression analyses were performed. ROC analysis was used to compare MUC baseline values and Mayo Endoscopic Scores (MES) in predicting colectomy risk.Overall, 141 patients were enrolled, and 13 underwent colectomy in the follow-up period. Both MES (HR: 3.15, 95% CI: 1.18-8.37, p=0.02) and MUC (HR: 1.48, 95% CI: 1.19-1.76, p <0.001) were associated with colectomy risk, but only MUC was independently associated with this event at multivariable analysis (HR: 1.46, 95% CI: 1.06-2.02, p=0.02). MUC was the only independent variable associated with colectomy risk in patients with clinically active disease, OR: 1.53 (1.03-2.27) P=0.03. MUC demonstrated higher accuracy than MES (AUROC 0.83, 95% CI: 0.75-0.92 vs. 0.71 95% CI: 0.62-0.80) and better performance for predicting colectomy (p=0.02). The optimal MUC score cut-off value for predicting colectomy, as assessed by the Youden index, was 7.7.A superior predictive value was found for transmural versus endoscopic severity for colectomy risk in UC patients.