Histologic healing and clinical outcomes in ulcerative colitis.

Background/aims: Growing evidence suggests histologic healing (HH) improves clinical outcomes in ulcerative colitis (UC) patients beyond endoscopic healing (EH). We hypothesize that HH is associated with better clinical outcomes in Asian UC patients, for whom data is lacking.

Methods: We performed a retrospective study of UC patients in clinical remission (CR) with a follow-up colonoscopy and minimum 1-year follow-up post-colonoscopy. Primary outcome was clinical relapse (CRL), defined as either a Simple Clinical Colitis Activity Index score of > 2, medication escalation, hospitalization or colectomy. Predictors of CRL and HH were assessed.

Results: One hundred patients were included with a median follow-up of 22 months. At index colonoscopy, 80 patients were in EH. On follow-up, 41 patients experienced CRL. Of 80 patients in EH, 34 (42.5%) had persistent histologic activity (Nancy Index ≥ 2) and 29 (36.3%) relapsed during the follow-up period. Amongst patients in CR and EH, those with HH had lower CRL rate (26.1% vs. 50.0%, P= 0.028) and longer CRL-free survival (mean 46.1 months vs. 31.5 months, P= 0.015) than those with persistent histologic activity. On bivariable analysis of 100 patients in CR, HH, and Mayo endoscopic score (MES) of 0 were significantly associated with lower risk of CRL. On multivariable analysis, only MES 0 remained predictive of lower CRL risk.

Conclusions: Above and beyond CR and EH, achieving HH improves clinical outcomes in Asian UC patients. However, HH may not confer incremental benefit if MES 0 has been achieved. Further prospective studies evaluating the benefit of histologically guided therapeutic decisions are needed.