Validation of an ambient measurement system (AMS) for walking speed

Journal of Medical Engineering & Technology – April 2017

“Validation of an ambient measurement system (AMS) for walking speed”. Jonathan S. Varsanik, Zebadiah M. Kimmel, Carl de Moor, Wendy Gabel, and Glenn A. Phillips (2017). Journal Of Medical Engineering & Technology, DOI: 10.1080/03091902.2017.1308025

The purpose of this study was to validate the measurement of walking speed by a shelf-top ambient measurement system (AMS) that can be placed in a patient’s home. Twenty-eight healthy adults (16 male, 12 female) were asked to walk three pre-defined routes two times each (total of 168 traversals). For each traversal, walking speed was measured simultaneously by five sources: two independent AMSs and three human timers with stopwatches. Measurements across the five sources were compared by generalized estimating equations (GEE). Correlation coefficients compared pairwise for walking speeds across the two AMSs, three human timers, and three routes all exceeded 0.86 (p < .0001), and for AMS-to-AMS exceeded 0.92 (p < .0001). Aggregated across all routes, there was no significant difference in measured walking speeds between the two AMSs (p = .596). There was a statistically significant difference between the AMSs and human timers of 8.5 cm/s (p < .0001), which is comparable to differences reported for other non-worn sensors. The tested AMS demonstrated the ability to automatically measure walking speeds comparable to manual observation and recording, which is the current standard for assessing walking speed in a clinical setting.


Movement Measurements at Home for Multiple Sclerosis: Walking Speed and Cane Usage Measured by an Ambient Measurement System

American Academy of Neurology (AAN) – April 2016

“Movement Measurements at Home for Multiple Sclerosis: Walking Speed and Cane Usage Measured by an Ambient Measurement System”. Scientific electronic poster (e-poster) presented at the American Academy of Neurology (AAN) annual conference on April 18, 2016. Authors: Victoria M. J. Smith (MGH / Harvard), Jonathan S. Varsanik (Atlas5D), Kevin R. Patel (MGH / Harvard), Wendy Gabel (Biogen), Glenn Phillips (Biogen), Zebadiah Kimmel (Atlas5D), Eric Klawiter (MGH / Harvard). Video contents copyright 2016 by Atlas5D; all rights reserved.

This study’s objective was to develop continuous in-home outcome measurements to assess gait in adults with multiple sclerosis (MS). Movement measurements were collected continuously for 4 months from the homes of six female people with MS (mean age 56.2, median EDSS 3.5, EDSS range 2-6.5). After two months, sensors were moved to a new location in the home. Spearman correlation was used to correlate in-home continuous gait outcomes with standard clinic gait outcomes. Wilcoxon signed-rank test was used to compare gait outcome for location and time of day. Measured in-home average walking speeds of users demonstrated a moderately strong correlation with Timed 25-Foot Walk (ρ=-0.60, p=0.21). Home cane usage was detected with cane users twice as frequently as non-cane users in a cane-detection measurement. New non-wearable technology provides reliable and continuous in-home assessment of walking speed and cane usage. This study demonstrates feasibility for development of new continuous outcome measures to assess gait in MS and other neurological diseases.