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P284. Assessment of mucosal healing in ulcerative colitis by confocal laser endomicroscopy

G. Hundorfean1, M.T. Chiriac1, M.F. Neurath1, J. Mudter1, 1University of Erlangen-Nuremberg, Medical Clinic 1 Erlangen, Erlangen, Germany

Background

Mucosal healing (MH) is the main goal in the treatment of IBD, incl. ulcerative colitis (UC). Monitoring of MH might be important to evaluate the response to therapy and the course of disease. The endoscopic assessment of MH using white light endoscopy (WLE) comprises macroscopic scores. The analysis of the mucosal microstructure using confocal laser endomicroscopy (CLE) might give new insights into MH during therapy and define more precisely MH.

Methods

The aim was to investigate the utility of CLE for assessing microscopic mucosal changes before and after the start of infliximab (IFX) therapy in UC and to provide and validate the first endomicroscopical MH-score (eMHS). Morphological criteria (crypt number, distortion, crypt erosions/ulcerations, goblet cell ratio, vascular leakage and cellular infiltrates) were evaluated and the eMHS was established. Consecutive UC patients (Mayo >6) were prospectively included and underwent colonoscopy with CLE before and after 3 IFX infusions. Based on the Mayo-score, 2 groups i.e. therapy responders (Mayo <3) and nonresponders (Mayo >3) were defined. A total of 300 random endomicrographs were analyzed in a blinded fashion by 2 endoscopists, as follows: 100 micrographs from responder group before and 100 micrographs after IFX infusions; 50 random micrographs were analyzed from the non-responder group before and 50 after IFX therapy – based on the eMHS ranging from 0 to 9.

Results

Responder group patients showed post-IFX an increase in crypt number and a decrease of eMHS. The differences between these two parameters were statistically significant in the responder group (P < 0.0001, in the unpaired t test). In the non-responder group, the differences between the pre- and post-treatment scores were not statistical significant (P = 0.3362, in the Mann–Whitney test). MH was defined as eMHS = 0. CLE residual activity (not visible using WLE) ranged from eMHS 0–3 and consisted in enlarged crypt lumen, leakage or hypervascularity.

Conclusion

Our new CLE classification system showed excellent accuracy with the therapy response assessed by clinical and endoscopic Mayo-score. Furthermore, microscopic aspects allow a more precise assessment of MH. CLE can accurately assess MH in vivo based on the newly developed and statistically validated eMH-score for UC.