Govert Veldhuijzen

99 CBE is non-inferior to nurse counselling prior to colonoscopy, a multicenter RCT Our randomized clinical trial comes with strengths and limitations. Summarizing strengths, our trial was conducted with a large, real life sample of patients. The non- inferiority hypothesis and power allows robust statements on CBE efficacy. We tested this CBE in a real-world setting, with patients with patients having a variety of indications (Appendix Table 3s), both with and without previous experience of colonoscopy. Also, we used three different types of endoscopy units, with a variety of different practices (Appendix tables 4s and 5s), so the results are well generalizable to daily practice. In the catchment area of our endoscopy centers, CBE can be used in up to 94% of patients undergoing colonoscopy. 11 On the other hand, our trial comes with limitations. There was a significant number of dropouts after randomization due to inclusion failures. However, this did not result in an unequal distribution regarding baseline characteristics among the arms in both the ITT and PP population, limiting the risk of selection bias. Due to the use of patient reported questionnaires we do not have 100% data collection at all time points, although the trial protocol called for that. While this did not affect our main outcome, it might have affected assessment of secondary outcomes such as anxiety and satisfaction. Satisfaction was measured several hours after administration of sedatives. Sedatives may cause a euphoric effect after administration and result in higher overall scores. However, type of sedative use was distributed equally (data not shown) over the groups, precluding bias. We did not collect complete medical histories of our patients, including previous abdominal surgery, or risk factors for poor bowel preparation such as diabetes mellitus, constipation, or use of motility influencing drugs. We surmise that the effect of these risk factors on the bowel preparation efficacy in our trial is limited in view of the small difference in BBPS scores. We did not collect data on adenoma detection rate (ADR) as this was outside the remit of this clinical trial. From literature, the robust correlation between adequate BBPS and ADR suggest that BBPS is a good technical proxy parameter. 35 CONCLUSION In this trial we have established non-inferiority for computer based education compared to nurse counselling prior to colonoscopy in bowel preparation. This finding paves the way for further upscaling of CBE in endoscopy units to prepare their patients more effectively before colonoscopy. A patient prepared with CBE reduces the need for outpatient clinic capacity, leading to less absenteeism at work, high satisfaction scores and good re-collection of information. 5