Hypothesis / aims of study
The frequency-volume chart (FVC) is an essential diagnostic tool for assessing lower urinary tract symptoms (LUTS), commonly used in both clinical and research settings. However, it requires patients to manually record voided volumes and times, which is often burdensome and susceptible to inaccuracies. Moreover, healthcare professionals must manually interpret handwritten records and perform calculations, increasing the risk of human error and adding to the clinical workload.
To address these challenges, we developed the Urodiary Checker (UDC), a compact, fully automated urine measurement system, in collaboration with Ishida Medical Co., Ltd. The UDC allows patients to measure their voiding volume simply by placing a collection cup on the device. The volume and time are automatically recorded and transmitted via Bluetooth to a connected PC, where parameters such as 24-hour total urine volume, average voided volume per episode, nocturnal urine volume, and nocturnal polyuria index are automatically calculated and visualized. This eliminates the need for manual recording and calculation, potentially improving accuracy and reducing patient and staff burden.
The objective of this study was to evaluate the clinical utility and usability of the UDC compared to the conventional FVC, by directly comparing recorded data and assessing user experience using a validated usability scale.
Study design, materials and methods
This was a prospective, single-arm, observational study conducted at the University of Fukui Hospital and affiliated institutions between April 2023 and March 2025. Patients with lower urinary tract symptoms (LUTS) were enrolled. Each participant was instructed to complete a 3-day frequency-volume chart (FVC), followed by a 3-day measurement period using the Urodiary Checker (UDC).
After completing each method, usability was evaluated using the System Usability Scale (SUS), a validated 10-item questionnaire using a 5-point Likert scale.
Urinary parameters such as 24-hour total urine volume and average voided volume per episode were collected from both methods. Spearman’s rank correlation coefficients were calculated to assess the consistency of the values between FVC and UDC. SUS scores were compared using paired t-tests. All statistical analyses were performed using JMP® Pro 17.0 (SAS Institute Inc., Cary, NC), and p-values less than 0.05 were considered statistically significant.
Results
A total of 40 patients participated, and 31 (77.5%) successfully completed both methods and were included in the final analysis. The mean age was 67.8 ± 4.7 years; 19 were male and 12 female. The mean 24-hour urine volume was 1628.0 ± 504.2 mL for FVC and 1458.3 ± 482.3 mL for UDC (Spearman’s r = 0.86, p < 0.001). Average voided volume per episode was 173.6 ± 53.2 mL for FVC and 163.0 ± 52.8 mL for UDC (r = 0.77, p < 0.001), indicating strong agreement between the two methods.
SUS scores were significantly higher for UDC (78.9 ± 13.7) compared to FVC (58.6 ± 20.5) (p = 0.006), demonstrating greater ease of use and acceptability by patients, with the mean UDC score also exceeding the commonly accepted usability benchmark of 68 points.
Interpretation of results
The strong correlation between FVC and UDC data confirms the accuracy and reliability of the UDC for capturing voiding behavior. Moreover, the significantly higher SUS scores indicate a clear advantage in usability, especially among older patients who often struggle with manual recording. The automation and visualization features of UDC may lead to improved compliance, reduced patient burden, and more accurate clinical decision-making.