Many individuals with overactive bladder (OAB) rush to the toilet to urinate due to urgency associated with bladder sensation and the degree of bother associated with urgency often drives individuals to seek treatment. As a result, there is growing interest in metrics to characterize bladder sensation during the filling phase. A tablet-based “Sensation Meter” was recently developed to record patient-reported sensation of bladder fullness throughout filling and enable the construction of sensation-capacity curves [1, 2]. The objective of the present study was to correlate sensation-capacity curve patterns with the severity and bother associated with the symptom of urinary urgency.

Individuals were screened for this prospective study using the International Consultation on Incontinence OAB questionnaire (ICIq-OAB). Participants with a score of ≥2 on question 5a about how often they rush to the toilet (0 = never, 4 = all of the time) were categorized as having OAB and were included in the study. These individuals with OAB were subdivided into two groups based on their ICIq-OAB question 5a scores. Those with a 5a score of 2 were placed in a “moderate urgency” group and those with scores of 3 or 4 were placed in a “severe urgency” group.  Participants were also divided into two groups based on their ICIq-OAB question 5b about how much rushing to the toilet bothers them (0 = not at all, 10 = a great deal). Participants with 5b scores ≥8 were placed in a “high bother” group and those with 5b scores <7 were placed in a “low/moderate bother” group.

Throughout the filling phase of a urodynamics study, each participant recorded his or her bladder fullness sensation on a 0-100% scale using the Sensation Meter. Sensation data were sampled at 5% capacity increments and sensation-capacity curves were constructed for each participant. Area-under-the-curve analysis was implemented to differentiate between “r,” “l,” and “j” sensation-capacity curve shapes (Fig 1). The r-shaped curves exhibited much greater increases in sensation during the first half of filling, while the j-shaped curves demonstrated much greater increases in sensation in the second half of filling (Fig 1). For an l-shaped curve, sensation increased relatively linearly throughout filling (Fig 1).  These “r,” “l,” and “j” curves were categorically correlated with the moderate and severe urgency groups and with the low/moderate and high bother groups.

This study included 69 participants (17 men and 52 women). The distribution of sensation-capacity curve shapes was 7 (10%) “r,” 43 (62%) “l” and 19 (28%) “j.”  Participants with “r” and “l” curves were split evenly between the moderate urgency group (25/50, 50%) and the severe urgency group (22/50, 50%). In contrast, those individuals with “j” curves predominately had high bother (15/19, 79%) compared to low/moderate bother (4/19, 21%). Similarly, participants with “r” and “l” curves were split relatively evenly between the low/moderate bother group (23/50, 46%) and the high bother group (27/50, 54%). However, most individuals with “j” curves had high bother (17/19, 89%) compared to low/moderate bother (2/19, 11%). The group with j-shaped curves was significantly associated with both severe urgency and high bother (Fisher’s Exact, p<0.05).

A sensation-capacity curve with a large increase in bladder fullness sensation near the end of filling was defined as a j-shaped curve, and this relatively rapid increase in sensation was associated with both the severity and bother associated with urinary urgency.

This study introduced a novel method to categorize sensation-capacity curves with “r,” “l,” and “j” shapes, and identified an association between j-shaped curves and both the severity and bother associated with urinary urgency. Additional studies are needed to determine whether sensation-capacity curves can be used to identify relevant OAB sensation subtypes.

Nagle AS, Speich JE, De Wachter SG, Ghamarian PP, Le DM, Colhoun AF, Ratz PH, Barbee RW, Klausner AP. Non-invasive characterization of real-time bladder sensation using accelerated hydration and a novel sensation meter: An initial experience. Neurourol Urodyn. 2017;36(5):1417-1426.
Sheen D, Kolli H, Nagle AS, Cullingsworth Z, Vinod NN, Naimi HA, De Wachter SG, Mazzeo SE, Stothers L, Speich JE, Klausner AP. Validation of a real-time bladder sensation meter during oral hydration in healthy adults: Repeatability and effects of fill rate and ultrasound probe pressure. Low Urin Tract Symptoms. 2019;11(4):224-231.