In 2023, colon capsule endoscopy (CCE) was introduced across 10 pilot centres in Ireland as part of a strategy to improve access to gastrointestinal diagnostics and reduce pressure on colonoscopy services. The major limitations of CCE are issues with complete transit, inadequate preparation, and the requirement for post-CCE standard endoscopy. The aim of this study was to explore predictors of real-world CCE performance with a view to identifying patients most likely to benefit from a CCE.

Data was prospectively collated from six colon capsule centres participating in the Irish Capsule Endoscopy Registry (ICaRe) over 2 years. Procedural data is voluntarily uploaded from each centre to an anonymised, web-based system on a continuous basis. Analysis was performed on available data captured on the registry. The key outcomes assessed were complete study rate (defined as adequate preparation and complete transit), the rate of significant findings, and the requirement for post-CCE endoscopy. Predictors assessed included age, gender, and indications for CCE. Indications were grouped as screening (FIT-positive or family history), polyp surveillance, symptomatic patients (high or low risk symptoms and/or anaemia), incomplete colonoscopy for any indication, and patient preference. Standard univariate analyses and multivariable logistic regression were used to identify factors associated with key CCE performance outcomes.

A total of 789 CCEs were included, 354/789 (45%) male, mean age 55.3 years (range 22–87). The ranked CCE indications were symptomatic patients (44%), incomplete colonoscopy (22%), polyp surveillance (16.5%), screening (15.5%), and patient preference (2%). Overall complete study rate was 73% (573/789), adequate preparation rate 84% (625/748), significant findings rate 56% (445/788), and post-CCE endoscopy rate 40% (319/789), including 243 (31%) colonoscopies. Completion rates by indication ranged from 65% for surveillance to 82% for screening patients, while the post-CCE endoscopy rate (excluding the patient-preference group who were outliers at 7%, likely due to small numbers) ranged from 33% for the incomplete colonoscopy group to 50% for surveillance patients. On multivariate analysis, the only independent predictor of outcomes was the indication for CCE. Specifically, those undergoing CCE for surveillance of previous polyps were significantly more likely to require a post-CCE endoscopy (50%) (OR 1.61; 95% CI 1.1–2.4; p = 0.01), likely related to the higher significant finding rate also found in this group (p = 0.03). Of interest, the surveillance group also had a higher incomplete study rate (35%), possibly reflecting a selection bias in this cohort where they were referred for CCE surveillance rather than a colonoscopy. Unsurprisingly, as the distal colon would already have been examined, those undergoing CCE following an incomplete colonoscopy were less likely to require a post-CCE endoscopy (OR 0.7; 95% CI 0.49–0.99; p = 0.05). As expected, increasing age was associated with a higher diagnostic yield overall (p = 0.005). However, older age (>70 years) was not associated with worse outcomes. The complete study rate was 27% (174/645) in patients ≤70 years versus 29% (40/138) in those >70 years, and the post-CCE endoscopy rate was 41% (262/645) ≤70 versus 41% (57/138) >70. Similarly, gender had no impact on outcomes.

Clinical indication significantly affects CCE performance and should be used as a tool to help select patients most likely to benefit from this procedure. Surveillance patients of any form appear to be less suited to CCE. Older patients, based on our data, should not be excluded from CCE.