Baseline characteristics of participants recruited into the COLO-COHORT study: a UK-wide resource for colorectal cancer prevention

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Objective To describe the design, recruitment, and baseline characteristics of the first phase of COLO-COHORT and to establish this population as a resource for colorectal cancer (CRC) prevention research. Methods COLO-COHORT is a prospective, multicentre observational study recruiting adults undergoing colonoscopy through screening and routine National Health Service referral pathways within a 32-site UK network. We present descriptive data from the first 4754 participants, recruited through 27 Phase 1 sites, including demographics, lifestyle factors, clinical characteristics, biospecimen availability and colonoscopy outcomes. Results Participants had a median age of 64 years (IQR 57–70), and 54.3% were male. Overweight (38.0%) and obesity (30.5%) were common, and cardiometabolic comorbidities were prevalent (11.8% with type II diabetes; 39.4% with hypertension). Colorectal neoplasia was identified at colonoscopy in over half of participants (56.1%), with histologically characterised data available on polyp type, size, morphology and anatomical location. Core demographic and clinical variables were available for >95% of participants, with colonoscopy findings recorded for all. Linked blood and stool microbiome biospecimens were available for approximately 80% and 40% of participants, respectively. Conclusion This paper establishes and characterises COLO-COHORT’s Phase 1 study cohort as a well-phenotyped resource, representing a population of individuals undergoing colonoscopy via UK screening and routine clinical pathways. This cohort will support and underpin future collaborative clinical, epidemiological and translational research in CRC prevention.