HIDRATE-PRO: A prospective pilot study evaluating a digital behavioral health intervention to improve bladder-filling compliance in patients with prostate cancer receiving radiation.

70 Background: Prostate cancer (PCa) patients undergoing radiation therapy (RT) need comfortably full bladders during RT to reduce toxicities. Awareness of this state is lacking, and poor compliance is common with standard of care written/verbal instructions, leading to wasted patient value (PV) and inefficient throughput (TE). Herein, we assessed the feasibility and acceptability of a digital behavioral intervention (DBI) to improve bladder filling compliance, methods for quantifying PV, IT, and behavioral biomarkers. Methods: We enrolled 18 non-metastatic PCa patients in a prospective, single-arm pilot study using a DBI. The DBI consists of a smart water bottle and companion app that tracks water consumption. Additionally, visual alerts (water bottle glow and phone notifications) remind the patient to empty his bladder and drink a personalized volume goal (VG) at a set time. The VG is based on simulation bladder volume and reminders are initially set 1.25 hours prior to scheduled RT. Patients were trained to adjust their VG and notification times to achieve comfortably full bladders. Primary endpoint was met if qualitative (QLC) and quantitative compliance (QNC) were both >80%. Other endpoints include acceptability assessed via Service User Technology Acceptability Questionnaire (SUTAQ), engagement (>80% of patients used the device > 50% of the time) and impact of DBI on PV and TE. For QLC, patients were asked if they prepared their bladders before daily RT. QNC was met if bladder volumes on daily CBCT were > 75% of the simulation’s volume. The SUTAQ was given pre- and post-DBI. PV and TE were measured by time spent in clinic and on the linear accelerator (linac), respectively. Biometric data was probed for insights on optimal drinking behaviors. Results: All endpoints were met. QLC was 100% on 375/398 (94.2%) of total treatments, while QNC was 88.9% on 341/398 (85.7%) total treatments. Patients were accepting of DBI with few privacy concerns (4.33/5.00), believe in benefits (4.00/5.00), high satisfaction (4.56/5.00) and high usability (4.24/5.00). Most patients, 15/18 (83.3%), used the DBI on >50% of treatments and met the engagement requirements. Patients with empty bladders (n=43) spent significantly more time (75.14 vs 50.59 minutes, p=0.007) in clinic than patients who came with full bladders (n=355). Similarly, these patients spent nearly twice as long on the linac (21.63 v 12.50 minutes, p<0.001). Shorter time spent drinking correlated with empty bladders (17.07 vs 27.85 min, p=0.027). Conclusions: This digital intervention trial showed high rates of bladder filling compliance and engagement. High patient-value and throughput efficiency was feasibly quantified by shortened clinic times and linac usage, respectively. Future studies are needed to evaluate clinical outcomes, patient experience and cost benefit. Clinical trial information: NCT04946214 .