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Endoscopic assessment of the presence and severity of endoscopic lesions has become an essential part of clinical trials in ulcerative colitis and Crohn's disease, for both patient eligibility and outcome measures. Variability in lesion interpretation between and within observers and the potential bias of local investigators in patient assessment have long been recognized. This variability can be reduced, although not completely removed, by independent evaluation of the examinations by experienced off-site (central) readers, properly trained in regard to lesion definition and identification, that should be removed from direct patient contact and blinded to any other clinical or study data. Adding endoscopic demonstration of active disease to eligibility criteria has the potential to reduce placebo response rates, whereas in outcome assessment it has the potential to provide a more precise estimation of the treatment effect, increasing the efficiency of the study. Central endoscopy reading is still at the beginning of its development, and the paradigms of central reading need refinement in terms of the number of readers, the process by which a final score is assigned, the selection and sequence of central readers, and the endoscopic indices of choice.

Original publication




Journal article


Journal of Crohn's & colitis

Publication Date



10 Suppl 2


S542 - S547


Department of Gastroenterology, Hospital Clínic de Barcelona, IDIBAPS, CIBERehd, Barcelona, Spain


Humans, Colitis, Ulcerative, Crohn Disease, Observer Variation, Endoscopy, Digestive System, Treatment Outcome, Eligibility Determination, Outcome Assessment (Health Care), Clinical Trials as Topic, Patient Acuity