P0748 Characterisation of Remission Levels in Patients with Ulcerative Colitis Treated with 5-Aminosalicylates: Results of the CARUC-ASA Prospective Multicentre Study
Authors: Reenaers Dr C , Caenepeel C , Lambrecht G , Pouillon L , Baert F , Cremer A , Colard A , Claessens C , Billiet T , Gedolf J , Strubbe B , Humblet E , de Zutter A , Rahier J F , Sommers M , Reynders D , Vansteenkiste L , Arijs I , Raeves A , Louis E , Verstockt B 
Published: January 2025

Abstract

Background
The treatment goals for chronic inflammatory bowel diseases are increasingly ambitious, targeting steroid-free remission, mucosal healing, and biomarker normalisation. In ulcerative colitis (UC), histological remission lowers risks of hospitalisation, cancer, and relapse. This study aims to describe remission levels in UC patients in symptomatic remission on first-line 5-aminosalicylic acid (5-ASA) and factors associated with remission.

Methods
This national, multicentre, prospective, phase 4 interventional study (ClinicalTrials.gov: NCT05992142) included UC patients in symptomatic remission, defined by a stool frequency score ≤ 1 and no rectal bleeding, on 5-ASA monotherapy (oral and/or rectal) for at least 6 months. Patients on corticosteroids, immunomodulators, biologics, or small molecules were excluded. Assessments included stool frequency, rectal bleeding, urgency, rectosigmoidoscopy (Mayo score, UCEIS), biopsies with the Geboes score assessed by central reading, faecal calprotectin (FCP), and MARS (Medication Adherence Report Scale) questionnaire. The different levels of remission were defined as followed: Complete Symptomatic Remission (CSR: PRO-2 = 0, no urgency), Endoscopic Remission (ER: Mayo 0–1, UCEIS 0–1), Complete Endoscopic Remission (CER: Mayo 0, UCEIS 0–1), Histological Remission (HR: Geboes 0–1), and FCP &lt;150 μg/g; and Deep Remission as combined CCR, CER, and HR. In the absence of CER, physicians completed a questionnaire to investigate the reasons for not altering therapy.

Results
From December 2022 to February 2024, 198 UC patients (median age 50, 41% female) were enrolled from 14 centres. Montreal classifications were E1 (37%), E2 (44%), and E3 (18%). Treatment included oral 5-ASA (n=134, 68%), rectal 5-ASA (n=19, 9%), and a combination (n=45, 23%) with a median duration of 2.0 years (1.0 - 4.0). The median MARS-5 score was 24. ER was observed in 172/198 patients (87%), CER in 138/198 (70%), and HR in 156/196 (80%). Among those in ER and CER, 151/172 (88%) and 127/137 (93%) also had HR, respectively. Normal FCP was seen in 152/194 (78%) and in 128/153 (83%) of the HR subgroup. Deep remission was achieved in 47/197 (24%) of patients. The main reason for absence of deep remission was the absence of CSR (63%). The main reason for not altering treatment, despite the absence of CER, was physician reluctance in 37% of cases. 5-ASA administration form was significantly associated with ER (p=0.5, OR=2.9, 95%CI 1.1-7.3) for oral against combined.

Conclusion
In UC patients in clinical remission on 5-ASA, the majority achieved endoscopic and/or histological remission, suggesting that higher remission levels beyond clinical remission alone are attainable in selected, highly adherent patients on first-line therapy.