Measuring sit-to-stand timing variability over time using under mattress pressure sensor technology

Getting out of bed is a fundamental activity of daily living and one that supports independent living. Under mattress pressure sensor technology represents a way to monitor changes in this basic but critical mobility task among older adults at risk of institutionalization. However, little is known about normal variations in this ability over time in the home context. This study used under mattress pressure sensors to measure and analyze the variability of sit-to-stand (STS) timing in a community-dwelling older adult. A pressure-sensitive mat was installed in the participant's home and left in place to collect information over a period of nine months. A processing algorithm was developed to extract the STS phase of the first morning bed exit from which STS time could be measured. STS timing data were visualized using a histogram and analyzed for trends over the extended period using nonparametric regression and wavelet analysis. Results indicate that the analytical methods used were able to identify trends in STS timing as well as highlight deviations. The ability to collect and analyze the variability of STS timing using this pressure sensitive technology combined with the analysis methodology provides clinicians with a way to assess mobility remotely in the home setting.