Sensor-based foot-mounted wearable system and pressure sensitive gait analysis : Agreement in frail elderly people in long-term care.

BACKGROUND The RehaWatch® system is a portable accelerometer for measurement of gait parameters that shows good validity in young adults; however, validity data are missing for elderly persons in long-term care (LTC). AIM The aim was to evaluate the concurrent validity of the RehaWatch® system using the GAITRite® system as a criterion reference for gait assessment in the LTC elderly. MATERIAL AND METHODS In this study 23 elderly participants (mean age 90.9 ± 8.4 years) performed 4 walking trials at normal and fast walking speed during single task and dual task walking. Data for both systems were collected simultaneously for each trial. Concurrent validity was assessed through limits of agreement (LoA) methodology using Bland-Altman plots. RESULTS No systematic bias could be determined. Mean biases for step duration, velocity and cadence were above the prespecified ±7 % value from zero lines for normal walking during single task and dual task walking. The LoA had a wide range between -21 % and 25 %. Only cadence showed small LoA for normal walking speed during single (-8.4 % to 7.7 %) and dual tasking (-4.1 % to 3 %). Heterogeneous bias was determined for step duration during fast walking during dual task and for velocity during fast walking during single task and dual task. Heteroscedasticity was shown for step length during normal walking under the dual task condition and fast walking during single task and dual task activities. CONCLUSION No gait parameters are interchangeably usable between the two systems for normal walking during single task and dual task activities.