Reliability and Validity of a Wireless Accelerometer for the Assessment of Postural Sway

Abstract

Clinicians are in need of valid and objective measures of postural sway. Accelerometers have been shown to be suitable alternatives to expensive and stationary force plates. We evaluated the test-retest reliability and balance task discrimination capability of a new wireless triaxial accelerometer (YEI 3-Space Sensor). Four testing conditions (eyes open or closed, while on a firm or compliant surface) were used to progressively challenge the static balance of 20 healthy male (n = 8) and female (n = 12) older adults (mean age 81 ± 4.3 y). Subjects completed 2 blocks of three 30-second trials per condition. The accelerometer was positioned on the lower back to acquire mediolateral (M-L) and anterior-posterior (A-P) accelerations. Intraclass correlation coefficients were all good to excellent, with values ranging from .736 to .972 for trial-to-trial and from .760 to .954 for block-to- block. A significant stepwise increase in center of mass acceleration root mean square values was found across the 4 balance conditions (F[1.49, 28.26] = 39.54, P < .001). The new accelerometer exhibited good to excellent trial-to-trial and block-to-block reliability and was sensitive to differences in visual and surface conditions and acceleration axes.

Psychometric Properties of Instrumented Postural Sway Measures Recorded in Community Settings in Independent Living Older Adults

“…Conversely, the current study had lower reliability than the study of Saunders et al (2015), [9] who reported ICCs ranging from 0.77-0.93 for standing on a firm surface with eyes open and closed and ICCs from 0.76-0.95 for standing on foam surface. There are several possible reasons for the higher reliability in the Saunders study.…”

“…Accelerometers are used to quantify postural sway during standing, and have been shown to have the ability to discriminate between test conditions that require different levels of postural control, between fallers and non-fallers, and young versus older adults [7][8][9]. Assessing balance by using accelerometers has been applied to different populations including people with Parkinson disease [10], stroke, children, and with community-dwelling older adults [11,12].…”

“…However, these accelerometer reliability studies were limited to clinical and lab settings, and had not been investigated outside in the community. Recently, a study by Saunders et al, found good to excellent test-retest reliability in using a tri-axial accelerometer to assess postural stability in people who live in independent living facilities [9].…”

Psychometric Properties of Instrumented Postural Sway Measures Recorded in Community Settings in Independent Living Older Adults

“…Accelerometers are used to quantify postural sway during standing, and have been shown to have the ability to discriminate between test conditions that require different levels of postural control, between fallers and non-fallers, and young versus older adults [7][8][9]. Assessing balance by using accelerometers has been applied to different populations including people with Parkinson disease [10], stroke, children, and with community-dwelling older adults [11,12].…”

The Quantification of Hop Landing Balance Using Trunk-Mounted Accelerometry

“…Accelerometers have quantified balance across a range of disease states and task conditions. [3][4][5][6] Accelerometers commonly mounted on the low back or sacral area have high reported correlation with force plate measures of balance. 3,7,8 Although it is acknowledged that the 2 measurement techniques measure subtly different constructs of balance (sway of center of pressure vs sacral acceleration), their relationship suggests that accelerometry offers a valid measurement method for balance.…”