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An Ambulatory Sensor-Based System for Quantification of Nighttime Micturition for Accurate Nocturia Assessment
By B.M Eskofier, J. Paulus, U. Paulsen, M. Burkart, B. Wullich, and V. Huppert.
2014 36th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBC 2014
2 November 2014, Article number 6943654, Pages 566-569
In this paper, the authors propose a sensor-based system for ambulatory quantification of nocturia frequency and evaluate its accuracy, starting from the assumption that an automatic, sensor-based measurement system would allow measuring objective data and provide better accuracy for treatment definition and medical intervention evaluation. Indeed, the use of such an instrument should avoid problems related with patients’ embarrassment during a visit interview or while recording a questionnaire, and could overcome patients’ difficulties in remembering the task. Automatic, sensor-based assessment systems with similar constraints have recently been developed for the assessment of sleep, daily life activities, and some medical conditions such as Parkinson’s disease, stroke and and arrhythmia.
The proposed system consisted of two components that were given to study participants for ambulatory use. The first component was a sensor watch which was worn by the participants and collected activity data. The second component was a room occupancy sensor which was placed in the bathroom of the participant and collected room occupancy data. The watch was worn by participants on the wrist of the preferred arm during the complete study period. Participants were asked to use a button on the watch in order to indicate the beginning and end of their bedtimes; this data was saved. The room occupancy sensor was placed in a convenient location in the bathroom by the study coordinator before the beginning of the recording period of 14 nights. After the end of the study, data were downloaded from both components using commercially available software. The inclusion criteria of the study were a diagnosed benign prostrate syndrome and a resulting average number of nighttime micturitions of two or more. Six patients were included in the study and completed their quantification of nighttime urinary frequency. Overall, the results show that the system is accurate, with an average misdetection rate of 0.32 and a mean absolute deviation of 3.8% when comparing the average number of nighttime micturitions. This sensory-based system appears to be useful particularly for the precise quantification of nighttime micturitions over a longer study period; this is of crucial importance in the evaluation of patients affected by nocturia.
Nocturia is a widespread condition where patients need to micturate frequently during the nighttime. In order to define treatment and measure therapeutic success in nocturia, questionnaires are traditionally used for ambulatory assessment. However, questionnaires were reported to suffer from compliance, embarrassment and subjective bias. An automatic sensor-based system for quantification of nighttime micturition for accurate nocturia assessment would not suffer from these disadvantages, and its development was therefore the purpose of this study. We defined a sensor-based system for ambulatory use, consisting of a sensor watch and a room occupancy sensor. Using this system, we so far collected data from 6 participants and 82 nights in an ongoing study. We report the details of the system, as well as the data analysis. The system is very accurate, with an average misdetection rate of 0.32 and a mean absolute deviation of 3.8 % when comparing the average number of nighttime micturitions. This novel sensor-based nighttime micturition quantification system has the potential to be used as an objective ambulatory assessment tool for nocturia diagnosis and treatment.