A Reminder App for Optimizing Bladder Filling During Radiotherapy for Prostate Cancer: A Pre-study in Healthy Volunteers.

BACKGROUND/AIM: The risk of genitourinary toxicity during radiotherapy for prostate cancer was found to be lower for bladder volumes ≥200 ml. An app that reminds patients daily to drink water might be helpful. Before being investigated in patients, an app should be tested in healthy volunteers. MATERIALS AND METHODS: Thirty healthy volunteers were included in this prospective study and asked to test the app and affirm (=satisfaction) or negate nine statements. These statements belonged to the sections 'Download and installation' (two statements), 'Navigation' (two statements), or 'Content/functions' (five statements). If a satisfaction rate was <60%, the app was to be considered not useful. If it was <80%, the app needed optimization. iPhone users (n=18) were compared to Android users (n=12). RESULTS: Satisfaction rates (participants affirming a statement) were 90.0% (27 out of 30 participants) and 86.7% (26 out of 30 participants) regarding the two statements belonging to the Download and installation section. Regarding the two statements of the Navigation section, satisfaction rates were 100% (28 out of 28) and 96.6% (28 out of 29), respectively. For the Content/functions section, satisfaction rates were 79.3% (23 out of 29 participants) for the statement: "The app reminded me at the selected times". For the other four statements, satisfaction rates were each 100% (25 out of 25, 27 out of 27, 28 out of 28, and 29 out of 29 participants). Significant differences between iPhone and Android users were not observed. When looking at the subgroups of iPhone and Android users, two additional aspects were identified that needed modifications. CONCLUSION: Although the new reminder app was mainly rated usable, some modifications were required. Our findings highlight that a pre-study in healthy volunteers is important.