Better patient education prior to colonoscopy improves adherence to instructions for bowel preparation and leads to cleaner colons. The hypothesis of this trial is that computer assisted instruction (CAI) using video and 3D animations can maximize the effectiveness of nurse counselling and consequently improves bowel cleanliness. Furthermore, CAI will positively influence the patient experience.

Adults referred for colonoscopy were included in a Dutch large volume endoscopy unit. Exclusion criteria were illiteracy in Dutch and audiovisual handicaps. Patients were prospectively divided into two groups, one receiving nurse counselling and one receiving CAI and a nurse contact before colonoscopy. The main outcome, cleanliness of the colon during examination, was measured with the Ottawa Bowel Preparation Scale (OBPS) and the Boston Bowel Preparation Scale (BBPS). Patient comfort and anxiety were assessed at multiple time points: directly after the instruction and one hour before colonoscopy. Comfort was rescored 2 hours after colonoscopy. We also tested knowledge and comprehension one hour before colonoscopy. Statistical analyses included Mann-Whitney.

To conduct the study, a prospective single center endoscopist blinded controlled design was used.

Patients Consecutive patients older than 18 years referred for elective colonoscopy were included from March 2013 until November 2013 in a single large volume endoscopy center (over 4000 colonoscopies/year) in the greater Amsterdam Area in the Netherlands. Exclusion criteria were illiteracy in Dutch and audiovisual/mental handicaps.

Study design After informed consent was obtained, patients were divided in two groups: the control group received nurse counselling and the intervention group received computer assisted instruction (CAI). Next, patients scored comfort ("How comfortable are you?") and patient anxiety ("How anxious are you)"on a 5-point Likert scale. (T1) After this, the CAI group had a contact with a trained endoscopy nurse for practical matters like bridging in anticoagulant therapy, insulin dosage calculation and scheduling of the colonoscopy. Next, patients were scheduled for their colonoscopies, maximum 6 weeks after the counselling session.

One hour prior to colonoscopy patients scored comfort and anxiety on the 5-point Likert scale. Also patient knowledge and comprehension was tested in a 10-question survey on the provided counselling information (T2).

Post-colonoscopy, patients re-scored comfort on the 5-point Likert scale (T3). During colonoscopy, the endoscopist assessed the bowel cleanliness with the Boston Bowel Preparation Scale (BBPS). For more subtle differences the Ottawa Bowel Preparation Scale (OBPS) was used.

Computer assisted instruction As intervention an interactive CAI was designed, according to current best practices, like good accessibility, plain language and engaging the user. Therefore the information was presented stepwise. The CAI consisted of a web-based platform using video mimicking the patient journey with voice-over supported by photo's, 3D animation and instructive texts. The video was presented in short clips, maximal 45 seconds, to maintain the focus of patient. Patient interaction was ascertained by mandatory mouse-click after each item in the CAI. All informative elements, especially mandatory for informed consent for colonoscopy (risks, alternatives) were included.

Outcomes The primary outcome was cleanliness of the colon during examination as assessed by the OBPS and the BBPS. The secondary outcomes were patient comfort, anxiety and knowledge and comprehension.

Statistical analyses The sample size of 350 provides 80% power, with a two-tailed α of 0.05, to detect an increase in the primary outcome measure from 6.0 in the control group to 6.3 in the experimental group.

All analyses were performed using SPSS version 20.0 for Windows (SPSS Inc., Chicago, IL, USA). Descriptive statistics were used to describe baseline information including frequency count, percentage and mean ±standard deviation. Further analyses included the chi-square test, independent t-test and Mann-Whitney. P-values under 0.05 were regarded statistically significant.

Ethical considerations The study was approved by the ethical and executive board of the institute.

Inclusion Criteria:

• Patients >18 years who were referred for colonoscopy

Exclusion Criteria:

• Illiteracy in Dutch and audiovisual or mental handicaps