The purpose was to evaluate the performance (i.e. demonstrate that the Bladder Sensor can detect the bladder before urination among its adult intended user), safety, usability and clinical benefits of the wearable ultrasound Bladder Sensor in adult patients with urinary incontinence (UI) problems as well as their satisfaction and impact on quality of life after having used the device for 1 week. The primary hypothesis was to evaluate if the median bladder detection rate in the evaluated population is greater than the threshold of 85% (H0: ≤0.85, H1: >0.85, p-value <0.05).

This is the first interventional, non-invasive, monocentric, pivotal study to evaluate a Bladder Sensor and its accessories in adult intended users. The investigational device consists of a Bladder Sensor and the corresponding APP including all accessories (e.g., silicone adhesives, ultrasound gel).

The Bladder Sensor is intended to support children (ages ≥ 6 years) and adults (BMI ≤ 25 kg/m2) suffering from UI during day and/or night, in healthcare and homecare environment. It is a small, wearable, wireless, battery-operated ultrasound device which continuously monitors the filling status of the bladder and notifies the individual when it is time to go to the bathroom via a gentle vibration on the belly and/or a notification in the APP on an iPhone or Apple Watch. A double-sided silicone adhesive is used for fixation of the device to the lower abdomen and ultrasound gel is used to guide the ultrasound signal. 

Prior to the study enrolment, subjects with known UI problems were recruited online either via one mailing or through online advertisement. After enrolment of subjects (visit 0), baseline assessment and the instructions on how to use the Bladder Sensor were given (visit 1). On the same day, the Bladder Sensor was tested for 4-6 hours. Subjects were interviewed to take the decision if they want to continue or terminate the participation after they returned to the site. If subjects and site team decided to proceed, the Bladder Sensor was used independently at home for 6 to 7 days followed by a final assessment at the site (visit 2).

In total, 30 subjects suffering from UI during day and/or night tested a Bladder Sensor connected to an APP, either on an iPhone or an Apple Watch at home for 6.9 days on average. 12 subjects dropped out prematurely. 

Subjects, who completed the study were mainly females (67%, n = 20), with a median age of 53 years (IQR 32 – 61 years) and median BMI of 22.6 kg/m2 (IQR 20.7 – 23.8 kg/m2). Main disease-specific symptoms of these subjects were: unwanted urinary loss (90%), sudden overwhelming urge to urinate (86%), problems while emptying the bladder completely or knowing if the bladder is completely emptied (66%) and/or the frequent, strong urge to urinate (69%). Most often subjects were affected by their UI during the day (83%).

The null hypothesis was rejected among the study population without statistically and clinically identified outliers (n = 28, median bladder detection rate 89.8%, IQR 82.6%-95.3%; z = 69, p<0.05). 

97% of all subjects felt the vibrations of the Bladder Sensor and 73% indicated that the device and/or APP provided them with notifications on time before managing to go to the toilet. The silicone adhesive needed to attach the device to the lower abdomen was assessed very positively given a median score of 10 out of 10 for staying on the skin properly, no glue residue on the skin and/or device and the gel staying in place within the adhesive. 

The Bladder Sensor showed to have a positive effect on subjects’ UI problems after testing it for only a week. Wearing the Bladder Sensor led to subjects being less affected by their urinary problem during normal daily activities, sports and/or social life. They worried less regarding smell and felt less embarrassed therefore contributing to a positive change in the quality of life. Subjects felt that the Bladder Sensor facilitated their decision to go to the toilet on time (73%) and they reported a reduced the number of unwanted leakages (67%). In addition, they felt more in control over their incontinence issues while using the Bladder Sensor (77%). Hence, more than half of the sample believed that their wellbeing was improved due to having more insights and control over the body and not having any urine loss anymore. All in all, subjects rated the Bladder Sensor as useful by 7.5 in median (IQR 6 -8) on a scale of 0 (not useful) to 10 (very useful). 

No new safety concerns regarding the investigational device were identified.

The median bladder detection rate was 89.8% without outliers and therefore it was proven that the Bladder Sensor can detect the bladder under real-life conditions among its intended users. The bladder detection rate seemed dependent on anatomical limitations (e.g., BMI and body shape), bladder volume (low bladder detection rate < 100 mL) and/or proper fixation. Drop-out reasons were mainly due to anatomical limitations or struggling to process / remember all information given by the research nurses during the initial onboarding. 

The results show that the Bladder Sensor has a positive effect on the subject’s UI problems, their quality of life and overall well-being while testing it for only one week. It is assumed that the positive effect will be strengthened when users incorporate the use of the Bladder Sensor into their daily life and will become confident in using it for a longer period. Hence, a post-market follow-up study is recommended to access the long-term benefits of the Bladder Sensor as an adjunct tool in continence care management.

Subjects who successfully tested the Bladder Sensor for a week had a BMI < 25 kg/m2 (i.e., flat abdominal area, not too much loose skin) and a bladder volume of > 100 mL with main disease-specific symptoms such as: 1) unwanted urinary loss, 2) the sudden overwhelming urge to urinate, 3) problems while emptying the bladder completely or knowing if the bladder is completely emptied and/or 4) the frequent, strong urge to urinate. It was indicated after a week that using the Bladder Sensor facilitated their decision to go to the toilet, prevented them from unwanted urine loss and influenced their quality of life and well-being beneficially.

Continence 12S (2024) 101664
DOI: 10.1016/j.cont.2024.101664