DOP73 Predicting endoscopic improvement in Ulcerative Colitis using the Ulcerative Colitis Severity Index (UCSI)

Abstract

Background: Scoring indices used in clinical trials for moderate‐severe ulcerative colitis (UC) may lack specificity as a prognostic tool. We developed and internally validated a prognostic scoring index for UC patients on therapy that considers baseline patient‐reported outcomes, biomarkers, endoscopy, and histology for achieving one‐year endo‐scopic improvement (EI).Methods: This post‐hoc analysis of the UNIFI clinical trial (ClinicalTrials.gov identifier: NCT02407236) included 644 patients treated with ustekinumab induction therapy. Data were randomly split into 70% training and 30% testing cohorts. Baseline variables were assessed in multivariate analyses and variables with p <0.05 were assigned weights according to their relative prognostic value for predicting one‐year EI (Mayo endoscopic score (MES) ≤1). A cut‐off was obtained by calculat‐ing the maximum Youden index and validated in the testing cohort.Results: Prior biologic failure, albumin < 40 g/L, CRP > 5mg/L, Mayo stool frequency (SF) subscore, endoscopic erosions/ulcerations based on the UC Endoscopic Index of Severity, and histologic structural/archi‐tectural changes demonstrated significant associations with one‐year EI and included in the final model. The Ulcerative Colitis Severity Index (UCSI) was generated (Table 1) and the median UCSI score among all participants was 10.4 (IQR 7‐14.4, range: 2.2‐20), which had accept‐able discriminative ability for one‐year EI in the training [AUC: 0.78 (95% CI: 0.70‐0.86)] and testing cohort [AUC: 0.76 (95% CI: 0.68‐0.85)] (Table 2). Compared to the UCSI, the Mayo score demonstrated EI (p=0.0006). The UCSI also predicted one‐year endoscopic healing partial Mayo score (PMS) remission (PMS < 2), and PRO‐2 remission (SF and rectal bleeding subscore of 0) with significantly greater accuracy compared to the Mayo score. Similar findings were observed when the UCSI was compared with the adapted Mayo score. The maximum Youden index corresponded to a cut‐off of 10. Participants with a UCSI >10 had a lower probability of one‐year EI [27/104 (26%) vs. 40/76 (52.6%)]. Performance characteristics are detailed in Tables 3 and 4 Conclusion: The UCSI is an internally validated prognostic scoring tool that accurately predicts one‐year EI at baseline among patients with moderateto‐ severe UC on active therapy. The UCSI demonstrated greater accuracy for one‐year EI, EH, and clinical remission compared to the total and adapted Mayo score. The UCSI could improve disease management in UC by stratifying patients based on their predicted likelihood of long‐term outcomes.