Histological healing might be the ultimate therapeutic goal in ulcerative colitis (UC). Our aim was to investigate the association between histological disease activity as measured by a validated index and long-term outcomes in patients with UC.
An observational retrospective cohort study was conducted at the Nancy University Hospital between January 2014 and March 2020. All consecutive patients with confirmed UC undergoing colonoscopy with biopsies and available histological reports were eligible for inclusion.
A total of 156 patients were included (53% female with a mean age of 41.3 ± 15.4 years). About a quarter of patients were in histological remission (Nancy index=0) at baseline (n=42, 26.9%). Median follow-up was 30.5 months (range 0-75). Sixteen patients with histological disease activity at baseline (Nancy index ≥ 1) underwent surgery during follow-up compared with no subject in the histological remission group (14.0% vs 0.0%, respectively, p=0.01). Similarly, a higher rate of hospitalization was found in patients with histological disease activity at baseline than in the histological remission group (36.0% vs 7.1%, respectively, p=0,001). The Kaplan Meier analysis showed that patients with histological disease activity at baseline had a 5-year surgery rate of 16.7% (logrank p=0.01) and a 5-year hospitalization rate of 19.7% (logrank p=0.0002). In the multivariate regression model, Nancy index > 0 was independently associated with the risk of hospitalization (hazard ratio 8.88, CI 95% 2.5-31.1, p=0.0007).
UC patients with histological disease activity, as measured by the Nancy index, have a greater risk of surgery and hospitalization.

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