Histologic Remission (NANCY Index) is Superior to Endoscopic Mucosal Healing in Predicting Relapse Free Survival in...

Histologic activity is recognized as an important predictor of relapse in ulcerative colitis (UC) patients. Current treatment targets aim at mucosal healing; however, many patients continue to have histologic activity.

The aim was to assess histologic activity using the validated Nancy histologic index (NHI) score as a predictor of future relapse amongst UC patients in endoscopic and clinical remission.

In this retrospective cohort study, UC patients in clinical and endoscopic remission at a single tertiary center between 2015 and 2018, who underwent a surveillance colonoscopy were included. Clinical remission was defined by partial Mayo score (MSp) <2, and endoscopic remission was defined by Mayo endoscopic subscore (MES) ≤1. Histologic remission was defined by NHI <2. Predictive factors associated with the primary endpoint of clinical relapse were analyzed.

A total of 74 of 184 UC patients were included in the study. Amongst this cohort, 33 patients (45%) demonstrated histologic activity (NHI >1) at enrollment. The median follow-up time was 42 months (interquartile range: 26 to 63 mo) with median relapse free period of 30 months (interquartile range: 18 to 48 mo). Kaplan-Meier analysis demonstrated patients with MES 0 ( P =0.02) and histologic remission ( P <0.0001) had significantly longer relapse free survival. On multivariate analysis only histologic activity remained an independent risk factor of future clinical relapse (hazard ratio: 4.36, confidence interval: 1.68-11.27, P =0.002).

Histologic remission using the NHI independently predicts significantly longer relapse free survival and may be a superior therapeutic target than endoscopic remission.