Agreement and Reliability of Patient-Measured Post-Void Residual Bladder Volumes
Michael Jalfon, MD1, Mursal Gardezi, MD1, Dylan Heckscher, MD1, Devin Shaheen, BS2, Kaitlin R. Maciejewski, MS3, Fangyong Li, MS, MPH3, Leslie Rickey, MD, MPH1, Harris Foster, MD1, Jaimie A. Cavallo, MD, MPHS1.
1Yale School of Medicine, New Haven, CT, USA, 2Yale School of Nursing, West Haven, CT, USA, 3Yale Center for Analytical Sciences, New Haven, CT, USA.
BACKGROUND: Post-void residual bladder volume (PVR) measurement in the non-healthcare setting would be a valuable opportunity for remote monitoring of patients with voiding dysfunction. We hypothesized that patient self-measurement of PVR using a smart device-integrated portable ultrasound probe equipped with artificial intelligence (AI)-based automated bladder volume measurement software would demonstrate high reliability, strong agreement with provider measurement, and be preferred by subjects over provider measurements in the healthcare setting.
METHODS: Eligible adult subjects were enrolled during outpatient Urology visits. Subject PVRs were measured in triplicate by providers using each of the following FDA-cleared devices: standard bladder scanners (either the VerathonTM BVI 9400 System or the Verathon TM BladderScan Prime System), the portable ultrasound probe with AI-based automated bladder volume measurement software using ultrasound images (ButterflyTM US image mode), and the portable ultrasound probe with AI-based automated bladder volume measurement software using abstract images (ButterflyTM abstract mode). Subjects blinded to the provider measurements then self-measured PVR in triplicate using both the US and abstract modes. Subjects were randomized to use either ButterflyTM US mode or ButterflyTM abstract mode first following a brief tutorial. Subject-reported preferences and evaluations were assessed via electronic survey. Agreement between PVR measurements for each combination of devices was assessed via Bland-Altman analyses using a clinically acceptable difference threshold of 50 mL. Reliability was assessed via intraclass correlation (ICC). Two-sided statistical significance was set at p<0.05.
RESULTS: 50 subjects were enrolled. ICCs ranged between 0.95-0.98 for each device. Results of the Bland-Altman analyses are displayed in Table 1. Mean difference in PVR between provider standard bladder scanner measurement and subject self-measurement were 7.5 mL (95% limits of agreement: -71.73 mL, 86.73 mL) using ButterflyTM US mode and 9.34 mL (95% limits of agreement: -93.84 mL, 112.52 mL) using ButterflyTM abstract mode, respectively. No statistically significant differences in agreement were observed for any combination of devices when stratified by age, sex, BMI, or subject-reported dexterity. Statistically significant differences in agreement were observed between subject US mode and both provider standard bladder scanner (p=0.02) and provider abstract modes (p=0.03) when stratified by subject-reported technological comfort. Most subjects preferred self-measurement over provider measurement (74% vs 26%, respectively).
CONCLUSIONS: Subject self-measurement of PVR using smartdevice-integrated portable ultrasound probes is feasible, reliable, and preferred by subjects. Limits of agreement between subject self-measurement and provider standard bladder scanner measurement of PVR exceeded our clinically acceptable difference threshold, though the published inherent error of each ultrasound-based bladder volume measurement device should be considered. Additional studies are warranted to determine if longitudinal subject self-measurements of PVR in real-world settings facilitate remote monitoring of patients with voiding dysfunction.
|Method 1||Method 2||Bias||95% Limits of Agreement|
|Standard Bladder Scanner PVR Mean||Provider ButterflyTM US Image Mode PVR Mean||13.17||-59.65, 85.89|
|Standard Bladder Scanner PVR Mean||Provider ButterflyTM Abstract Mode PVR Mean||12.51||-55.30, 80.33|
|Standard Bladder Scanner PVR Mean||Patient ButterflyTM US Image Mode PVR Mean||7.50||-71.73, 86.73|
|Standard Bladder Scanner PVR Mean||Patient ButterflyTM Abstract Mode PVR Mean||9.34||-93.84, 112.52|
|Provider ButterflyTM US Image Mode PVR Mean||Provider ButterflyTM Abstract Mode PVR Mean||-0.65||-71.28, 69.97|
|Provider ButterflyTM US Image Mode PVR Mean||Patient ButterflyTM US Image Mode PVR Mean||-5.67||-91.19, 79.86|
|Provider ButterflyTM US Image Mode PVR Mean||Patient ButterflyTM Abstract Mode PVR Mean||-3.83||-105.05, 97.40|
|Provider ButterflyTM Abstract Mode PVR Mean||Patient ButterflyTM US Image Mode PVR Mean||-5.01||-85.48, 75.45|
|Provider ButterflyTM Abstract Mode PVR Mean||Patient ButterflyTM Abstract Mode PVR Mean||-3.17||-71.56, 65.21|
|Patient ButterflyTM US Image Mode PVR Mean||Patient ButterflyTM Abstract Mode PVR Mean||1.84||-87.99, 91.67|
|Note:Bias = mean difference of the measurements.Limits of agreement = 1.96 standard deviations from the mean difference.All values are expressed in mL.|
Back to 2023 Abstracts