Colon Capsule Endoscopy in the Routine Diagnostic Pathway for Colorectal Diseases (DanCap): Protocol for a Cluster-Allocated Crossover Trial

Background/Objectives: Colonoscopy is the standard examination for many symptomatic patients referred for lower-gastrointestinal investigation, but it is resource-intensive and may be a burdensome experience. Colon capsule endoscopy (CCE) offers a minimally invasive, sedation-free first-line examination, although clinically important findings, inadequate cleansing or incomplete transit can generate downstream colonoscopy. DanCap aims to compare the costs and clinical consequences of a CCE-first pathway with routine conventional colonoscopy (CC). Methods: DanCap is a single-centre, cluster-allocated crossover trial at Odense University Hospital, Denmark. General practice clinics follow CCE or CC according to the parity of their pre-existing provider number, with pathways crossing after 200 consecutive CCE participants; no trial-generated random allocation sequence is used. Eight hundred symptomatic adults aged >18 years referred for expedited lower-gastrointestinal investigation are planned. CCE participants with suspected cancer, any polyp ≥6 mm, inadequate cleansing or an incomplete examination are referred for colonoscopy. The primary outcome is pathway cost. Registered secondary outcomes and prespecified process measures include polyp and colorectalcancer detection, examination quality, reinvestigation and patient-reported consequences. FIT and microbiome are registered secondary outcomes; participation in the substudy is optional and the analyses are exploratory within the CCEpathway. Primary analyses will follow the assigned pathway and account for GP clinic clustering, period and allocation sequence. Expected Results: The trial will quantify the resource use and clinical consequences of implementing CCE in routine symptomatic practice. Conclusions: DanCap is intended to inform decisions about CCE pathway implementation rather than to establish unbiased whole-cohort test sensitivity or specificity. Trial registration: ClinicalTrials.gov NCT06475560; first submitted 20 June 2024 and first posted 26 June 2024. Recruitment began on 27 November 2024; the registry listed the study as recruiting when last updated on 19 March 2026.