Patient-reported Outcomes and Disability Are Associated with Histological Disease Activity in Patients with Ulcerative Colitis: Results from the APOLLO Study

Background and Aims Treating beyond endoscopic remission, aiming for histological remission, is an emerging target in ulcerative colitis [UC]. Patient-reported outcome measurements [PROMs] become increasingly important, but their association with histology is unclear. Methods Multiple PROMs were prospectively collected in UC patients undergoing colonoscopy. Mayo endoscopic sub-score [MES] and ulcerative colitis endoscopic index of severity [UCEIS] were determined, as well as the Nancy histological index [NHI] of the most affected area. Endoscopic remission was defined as MES and UCEIS 0, histological remission as NHI 0, and histo-endoscopic mucosal remission [HEMR] as a combination of both. Results A total of 109 assessments were collected in 80 patients with endoscopic and HEMR remission rates of 24.8% and 16.5%, respectively. Patients with HEMR had a significantly lower overall inflammatory bowel disease [IBD] disability [p <0.001] and disease activity score [p <0.001] as compared with patients without. In line, NHI correlated with the overall IBD-disk [r = 0.36, p <0.001] and simple clinical colitis activity index [SCCAI] score [r = 0.44, p <0.001]. Many individual components of both differed significantly between patients with and without HEMR. Although the overall accuracy of the IBD-disk [0.78] or SCCAI score [0.83] for HEMR is lower [p <0.005] than the MES or UCEIS [0.95], a cumulative IBD-disk score >35.5 and an SSCAI score >3.5 have a high negative predictive value [98.6% and 100.0%, respectively] to exclude HEMR. Conclusion Histo-endoscopic inactive disease is associated with reduced IBD disability, but not with complete absence thereof. PROMs for disability and clinical disease activity cannot fully replace histo-endoscopic findings, and should be considered complementary in patient-centred endpoint discussions. Nevertheless, PROMs have a high negative predictive value to rule out HEMR.