Govert Veldhuijzen

87 CBE is non-inferior to nurse counselling prior to colonoscopy, a multicenter RCT randomized controlled trial with a head to head comparison of traditional nurse counselling versus CBE. METHODS Study design and patients We performed a multicenter prospective endoscopist blinded randomized controlled trial. Patients were recruited from the gastroenterology department at four hospitals in the Netherlands. This included one academic, two urban and one rural based hospital. Patients were recruited and underwent their colonoscopy between September 2015 and December 2017. We included adults referred for complete colonoscopy requiring bowel preparation who could provide informed consent. Exclusion criteria were patients unwilling to participate, no internet access or relative with internet access, Dutch illiteracy, audio- visual handicaps or mental disabilities. An extensive version of the trial protocol has been published earlier. 10 Patients were involved in the development of the CBE utilizing focus groups for content feedback. The study group promoted the CBE for the wider public, being nominated in several jury and public award contests. The CBE won the public vote for the yearly award issued by the Dutch low literate patient society in 2015. Ethics The study was performed according to the principles of the 1975 Declaration of Helsinki. The CONSORT guidelines were followed for reporting our results. This study was approved by the Institutional Review Board (Medical Research Ethics Committee of the region Arnhem-Nijmegen, number 2015-1765. The trial is registered under the Dutch Trial Registry, NTR 5475. No commercial support was provided for the trial. Randomization Patients referred for colonoscopy were contacted in person or by telephone call to judge willingness to participate. We employed a structured script to explain goals of the trial. Reasons of patient’s unwillingness to participate were recorded. After giving consent to participate, the patient identification number and e-mail address was entered in a secured online tool (Appendix 1s, see Supplementary Material). This tool randomized patients in a 1:1 ratio per trial site and subsequently informed them by automated e-mail on the type of education, being either nurse counselling or CBE. All participating patients provided written informed consent. 5