Core Outcome Sets in Gastrointestinal Endoscopy and Procedural Medicine: A Scoping Review of the COMET Initiative Database

Core Outcome Sets in Gastrointestinal Endoscopy and Procedural Medicine: A Scoping Review of the COMET Initiative Database Purpose: This scoping review systematically maps the current landscape of Core Outcome Sets (COS) registered in the COMET (Core Outcome Measures in Effectiveness Trials) Initiative database, with a specific focus on gastrointestinal (GI) endoscopy and procedural medicine. Clinical trials in GI endoscopy frequently employ heterogeneous outcome definitions, variable follow-up intervals, and investigator-selected endpoints, resulting in fragmented evidence that is difficult to synthesize, compare, or apply in clinical practice. Despite the rapid growth of COS development across medicine—with over 1,600 registered studies to date—procedural fields, and GI endoscopy in particular, remain critically underrepresented. This review aims to quantify that gap and characterize the methodological approaches used in existing COS development efforts. Objectives: The primary objectives of this scoping review are to: (1) characterize the volume, temporal trends, and disease category distribution of all COS registered in the COMET Initiative database; (2) quantify the representation of gastroenterology and endoscopy-specific COS relative to other medical specialties; (3) describe the methodological approaches (e.g., Delphi surveys, consensus meetings, systematic reviews) and stakeholder engagement patterns used in COS development, with particular attention to patient and caregiver involvement; (4) identify gaps in endoscopy-specific outcome standardization that warrant future COS development; and (5) compare methodological and stakeholder engagement characteristics of procedural COS with non-procedural COS. Methods: This scoping review follows the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) guidelines. The data source is the COMET Initiative database, which catalogs all published and ongoing COS development studies. Data charting includes study characteristics (disease category, year of publication, nature/type of intervention), methodological approaches, stakeholder types and involvement, geographic scope, and target population. Quantitative analyses include descriptive statistics, temporal trend analysis, proportion comparisons using chi-square tests with Wilson score confidence intervals, and diversity indices (Simpson's, Shannon, Gini) to quantify outcome heterogeneity where applicable. All analyses are conducted in R using tidyverse conventions. A pre-specified statistical analysis plan accompanies this registration. Expected Outcomes: We anticipate this review will demonstrate that: (a) gastroenterology ranks among the lower tiers of disease categories by COS volume despite a substantial and growing clinical trial base; (b) endoscopy-specific COS represent less than 1% of all registered COS, with the majority of gastroenterology COS focusing on disease management (e.g., inflammatory bowel disease) rather than procedural interventions; (c) patient involvement in COS development has increased over time but does not differ significantly between procedural and non-procedural COS; and (d) critical gaps exist in outcome standardization for high-volume endoscopic procedures such as ERCP, EUS, and endoscopic mucosal resection. These findings will provide the empirical foundation for a program of research (the CORE project) aimed at developing multi-stakeholder, consensus-driven COS for priority GI endoscopy domains, paired with stakeholder-informed hierarchical composite endpoints and operator-aware analytic frameworks to improve the rigor, interpretability, and generalizability of endoscopy clinical trials. Reporting Guidelines: PRISMA-ScR (PRISMA Extension for Scoping Reviews)