Outcomes

The primary outcome was bowel preparation quality assessed using the Boston Bowel Preparation Scale (BBPS). The BBPS is a validated and reliable scale that rates bowel cleanliness for each colonic segment (right, transverse, and left) after washing, suctioning, and cleaning maneuvers have been performed by the endoscopist [27]. Each segment is scored on a scale from 0 to 3 (3 being the cleanest) [28,29]. Segment scores were summed to calculate the total BBPS, which ranged from 0 to 9. Bowel preparation was considered adequate when the total score was ≥6 and all segment scores were ≥2. This cut-off value has been shown to be adequate for detecting polyps >5 mm [28-30]. The endoscopists were blinded to the study groups. Secondary end points were adenoma detection rate (ADR), polyp detection rate (PDR), cecal intubation time, and withdrawal time. ADR and PDR were calculated by dividing the number of patients with at least one adenoma and one polyp, respectively, by the total number of colonoscopy patients (based on the histological diagnosis according to the revised Vienna classification) [19,20]. Withdrawal time included the time from starting withdrawal from the cecum to the final inspection of the rectum, including the time spent on washing, suctioning, and polypectomies.

Items from the PSQ-18 were transformed to bowel preparation education purposes to investigate patient satisfaction [26]. Scores for the following subscales were calculated by averaging the scores of the relevant questions: general satisfaction (items 3 and 6), technical quality (items 8 and 9), communication (items 1 and 2), time spent on education (item 7), and convenience (items 4 and 5). Responses to all items were given on a five-point Likert scale, ranging from strongly agree to strongly disagree. Patients in the smartphone app group were also asked to rate the user friendliness and design of the smartphone app on a 10-point scale.