Histological remission (NANCY index) is superior to endoscopic mucosal healing in predicting relapse-free survival in patients with ulcerative colitis in clinical and endoscopic remission

Abstract

Background Histological grade is increasingly recognised as an important predictor of relapse in ulcerative colitis (UC) patients. Current treatment targets aim at mucosal healing, however many patients continue to have histological activity. We aimed to assess histological activity using the validated Nancy histological activity score as a predictor of future relapse in UC patients in endoscopic and clinical remission.

Methods Patients with UC attending the inflammatory bowel disease clinic at a single tertiary centre between 2015 and 2018 were included. Patients in clinical and endoscopic remission who underwent a surveillance colonoscopy between 2009 and 2017 were identified. Clinical remission was defined by partial Mayo score (MSp) <2, and endoscopic remission was defined by Mayo Endoscopic Subscore (MES) ≤1. Patients with inadequate biopsies, <18 years old, previous colectomy, on oral or intravenous steroids, or hospitalised were excluded. Blind assessment of biopsies were performed by two expert histopathologists, and assigned a Nancy score with histological remission defined by Nancy ≤ 1 and histological activity Nancy 2-4. Predictive factors associated with relapse were analysed. Relapse was defined as MSp > 2, initiation of steroids, hospitalisation, and escalation or alteration of therapy.

Results 74 patients in both clinical and endoscopic remission were included in the study. Median follow-up time was 42 months (IQR 26–63 months) with median relapse free period of 30 months (IQR 18–48 months). Patients with MES 0 (p = 0.02, Figure 1) and histological remission (p ≤ 0.0001, Figure 2) demonstrated significantly longer relapse free survival. On multi-variate analysis only histological activity remained as an independent risk factor of future clinical relapse (hazard ratio 4.36, 95% CI 1.68–11.27; p = 0.002).