Measurement of Disease Activity in Ulcerative Colitis: Interobserver Agreement and Predictors of Severity

Background: Endoscopic evaluation plays a pivotal role in the assessment of treatment response in ulcerative colitis (UC). This study aimed to determine the interobserver agreement (IOA) for assessment of mucosal lesions, and to determine lesions predictive of global assessment of endoscopic severity (GAES). Methods: Fifty-one UC patients had digital videorecording of their colonoscopic examinations, edited into videoclips representative of five colonic segments (rectum, sigmoid, descending, transverse, ascending/cecum). Seven gastroenterologists specializing in inflammatory bowel disease (IBD) independently and blindly rated individual lesions and endoscopic severity for each segment and globally. Edema, erythema, stricture, loss of haustral folds, rigidity, and pseudopolyps were scored as absent or present while vascular pattern, granularity, ulceration, and bleeding-friability were scored using a predefined severity scale. The GAES was based on a 4-point scale and a 10-cm visual analog scale (VAS). The IOA among raters was estimated using Lin's concordance correlation coefficient (CCC). Strength of agreement was categorized as excellent (0.81-1.00), good (0.61-0.80), moderate (0.41-0.60), and fair (0.21-0.40). Linear regression analysis was used to identify lesions predictive of overall endoscopic severity and develop a scoring system for clinical use. Results: Granularity, vascular pattern, ulceration, bleeding/friability, and pseudopolyps had good IOA in most segments. There was excellent agreement for VAS and good agreement for GAES and the VAS was significantly associated with GAES (P < 0.001). Granularity, vascular pattern, ulceration, and bleeding-friability were significant predictors of overall endoscopic severity. Conclusions: Granularity, vascular pattern, ulceration, and bleeding-friability demonstrated good reproducibility and were predictors of the GAES in UC patients.