A Systematic Review of the Measurement of Endoscopic Healing in Ulcerative Colitis Clinical Trials: Recommendations and Implications for Future Research

Background: Assessment of endoscopic disease activity, as measured by various endoscopic evaluative instruments, is an essential part of quantifying disease activity in clinical trials in patients with ulcerative colitis (UC). Evaluative instruments have specific definitions and operating properties that influence the interpretation of clinical trial results. Our objective was to systematically review all endoscopic evaluative instruments that measure endoscopic disease activity in UC and to describe their definitions and operating characteristics (reliability, responsiveness, and predictive validity). Methods: We performed a systematic review of evaluative instruments assessing endoscopic disease activity in UC. MEDLINE (Ovid), EMBASE (Ovid), PubMed, the Cochrane Library (CENTRAL), and Digestive Disease Week abstracts of clinical trials were searched from inception to January 2013. Results: In total, 5885 studies were identified and screened for inclusion criteria. Four hundred twenty-two studies involving 31 evaluative instruments were identified. Two types of indices were found, numerical scoring systems and stepwise grading scales. Conclusions: Both the endoscopic evaluative instrument selected and the definition chosen for mucosal healing affect the validity of assessing endoscopic disease activity during a clinical trial for UC. Currently, the sigmoidoscopic component of the Mayo Score and the ulcerative colitis endoscopic index of severity show the most promise as reliable evaluative instruments of endoscopic disease activity. However, further validation is required.