Re-investigation rate following colon capsule endoscopy stratified by faecal haemoglobin concentration in a screening population

Background: Endoscopy units throughout the world have seen a substantial increase in colonoscopy activity. One way to keep patient waiting time acceptable could be to introduce alternative diagnostic modalities. Colon capsule endoscopy has been proven to have a high diagnostic accuracy, yet the re-investigation rates reported are too high. Faecal haemoglobin concentration may offer a valid measure for triaging patients between diagnostic modalities, due to its association with colonic pathology. Objective: To investigate the re-investigation rate and risk classification in complete colon capsule endoscopies in a screening population stratified by faecal haemoglobin concentration. Design: Cross-sectional analyses of a data set derived from the intervention arm of a large randomised controlled trial, CareForColon2015, conducted in the Region of Southern Denmark between August 2020 and December 2022. Methods: Complete colon capsule endoscopy investigations were identified, and the proportions of investigations leading to re-investigation by colonoscopy were calculated, stratified by faecal haemoglobin concentration. Further, the odds of re-investigation were estimated by logistic regression models and the odds of increased risk classification by ordinal regression models. Results: The re-investigation rate was 58.6% in 1413 complete colon capsule endoscopies out of 2030 procedures. There were no significant differences ( p = 0.312) in re-investigation rates between faecal haemoglobin concentration subgroups with 58.2%, 61.1% and 62.7% in the groups of 100–249, 250–499 and >499 ng hb/mL buffer, respectively. The odds of referral for re-investigation did not differ significantly either. The odds of increased risk classification (i.e. higher than level one) was 1.17 (CI 95% 0.92; 1.49, p = 0.211) for concentrations between 250 and 499 ng hb/mL buffer, and 1.40 (CI 95% 1.12; 1.77, p = 0.003) for concentrations above 499 ng hb/mL buffer, compared to 100–249 ng hb/mL buffer. Conclusion: Faecal haemoglobin concentration did not prove to be a stand-alone selection parameter for diagnostic modality in a faecal immunochemical test-positive colorectal cancer screening population, although it was significantly associated with an increased risk classification.