Lyon endoscopic submucosal dissection score: a preprocedure prediction model for operating time in colorectal endoscopic submucosal dissection

Background and Aims Colorectal endoscopic submucosal dissection (ESD) is an effective curative technique for superficial colorectal lesions but remains technically demanding, with variable procedure times. This study aimed to develop and validate a preprocedure predictive model for colorectal ESD duration in the era of traction-assisted strategies. Methods We retrospectively analyzed prospectively collected data from patients who underwent colorectal ESD at Edouard Herriot Hospital (Lyon, France). The derivation cohort included 423 cases (January-December 2024), and an independent temporal validation cohort included 148 cases (January-May 2025). A generalized linear model with a gamma distribution and log-link function identified independent preprocedural predictors of ESD duration. Variables were selected on the basis of univariate significance and the Akaike information criterion. Model calibration and discrimination were assessed using R 2 , mean absolute error, and classification accuracy at predefined thresholds (60, 90, and 120 minutes). A point-based score (Lyon ESD Dissection score, [LEDS]) and nomogram were derived from model coefficients. Results Median procedure time in the derivation cohort was 50 minutes (IQR, 30-90). Independent predictors of ESD duration included dissection speed of endoscopists, lesion location (flexures, appendix, cecum, and ileocecal valve), predicted lesion size, and suspected fibrosis (all P < .05). The LEDS provides a direct estimation of the expected procedure time in minutes based on these variables, showing a strong correlation between predicted and observed durations ( R 2 = 0.52). Classification accuracy was 76.1%, 82.2%, and 88.1% for thresholds of 60, 90, and 120 minutes, respectively. Validation confirmed good performance ( R 2 = 0.48) with 91.8% accuracy for procedures ≥120 minutes. Conclusions This validated preprocedure scoring system accurately predicts colorectal ESD duration, especially for longer procedures. It may facilitate scheduling, optimize resource use, and improve workflow in endoscopy units.