Pilot Voided Volume Validation Study: Sound-Based Smartphone Applications Can Accurately Measure Voided Volume

Background/Objectives: To test the accuracy of two sound-based voided volume measurement applications compared to voided volume based on the measurement of pre- and post-void weight using a high-resolution scale. Methods: Seven male and four female volunteers participated. Male and female volunteers used the ProudP and Healthy Bladder-Voiding Diary mobile apps, respectively, to measure sound-based voided volume (SVV). The difference between pre- and post-void weight was calculated and converted to mL to be the true-voided volume (TVV) using a high-resolution scale. A Pearson correlation coefficient and paired t-test were completed. Results: Eighty-two voids were recorded (42M/40F). Median male participant age was 25.9 years. Male SVV ranged from 42-790 mL and TVV ranged from 61-880 mL. Mean difference was 39 mL (95% CI, 18-59 mL). SVV and TVV comparison revealed a strong correlation (r = 0.977, p < 0.0001). Equivalence testing indicated a p-value of 0.022. Median female participant age was 25.0 years. Female SVV ranged from 28-440 mL and TVV ranged from 10-682 mL. Mean difference was 53 mL (95% CI, 22-84 mL). Equivalence testing indicated a p-value of 0.330. SVV and TVV comparison revealed a correlation (r = 0.888, p < 0.0001). Conclusions: The male and female app have a strong correlation to true void volume (male > female app) and can be used by patients to track voided volume at home. The male app accurately measures voided volume within 60 mL from the TVV; however, the female app is less accurate.