Users who were assigned to use a smartphone app downloaded a free app from the iOS App or Google Play stores titled "SB Colonoscopy Prep." The app informed subjects about their colonoscopy procedure, alerts them when to take their medications throughout the hours-long colonoscopy prep process and tells them when to arrive to the endoscopy suite.

Subjects in the control group were given a three-page document that described the procedure and instructed users on how to take the preparation medications. The written instructions had a list of frequently asked questions about colonoscopies and the URL of a website where users could view the animated video that was included in the app. The written instructions also contained the time and date of the procedure. All subjects were instructed to arrive one hour before their scheduled procedure.

We created a smartphone app that informs patients about their colonoscopy procedure, alerts them when to take their medications throughout the hours-long colonoscopy prep process and tells them when to arrive to the endoscopy suite.

Prep quality was measured with the validated Boston Scoring Scale. A score of 0, 1, 2 or 3 is given to the right, transverse and left colon based on the amount and consistency of stool visualized as well as the ease or difficulty of guiding endoscopic instrumentation during a colonoscopy. Higher scores indicate a cleaner colon and as per Lai, a Boston Score of 7 or above indicates an "excellent" prep. To eliminate bias, the four grading gastroenterologists did not know whether subjects had used written or app instructions.

Calls to the GI service were recorded by the GI staff.