Validation of a body-worn accelerometer to measure activity patterns in octogenarians.
OBJECTIVE
To determine the validity of a triaxial body-worn accelerometer for detection of gait and postures in people aged >80 years.


METHODS
Participants performed a range of activities (sitting, lying, walking, standing) in both a controlled and a home setting while wearing the accelerometer. Activities in the controlled setting were performed in a scripted sequence. Activities in the home setting were performed in an unscripted manner. Analyzed accelerometer data were compared against video observation as the reference measure.


METHODS
Independent-living and long-term-care retirement village.


METHODS
Older people (N=22; mean age ± SD, 88.1±5y) residing in long-term-care and independent-living retirement facilities.


METHODS
Not applicable.


METHODS
The level of agreement between video observation and the accelerometer for the total duration of each activity, and second-by-second correspondence between video observation and the accelerometer for each activity.


RESULTS
The median absolute percentage errors between video observation and the accelerometer were <1% for locomotion and lying. The absolute percentage errors were higher for sitting (median, -22.3%; interquartile range [IQR], -62.8% to 10.7%) and standing (median, 24.7%; IQR, -7.3% to 39.6%). A second-by-second analysis between video observation and the accelerometer found an overall agreement of ≥85% for all activities except standing (median, 56.1%; IQR, 34.8%-81.2%).


CONCLUSIONS
This single-device accelerometer provides a valid measure of lying and locomotion in people aged >80 years. There is an error of approximately 25% when discriminating sitting from standing postures, which needs to be taken into account when monitoring longer-term habitual activity in this age group.
National Institute for Health Innovation, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand. Electronic address: lm.taylor@auckland.ac.nz.
Lynne M
LM
Taylor
Institute of Epidemiology and Medical Biometry, Ulm University, Ulm, Germany; Department of Clinical Gerontology, Robert-Bosch Hospital, Stuttgart, Germany.
Jochen
J
Klenk
School of Rehabilitation and Occupation Studies, AUT University, Auckland, New Zealand.
Alistair J
AJ
Maney
Department of General Practice and Primary Health Care, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand.
Ngaire
N
Kerse
Department of Computer and Electrical Engineering, Faculty of Engineering, University of Auckland, Auckland, New Zealand.
Bruce M
BM
Macdonald
National Institute for Health Innovation, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand.
Ralph
R
Maddison
D061725:Accelerometry / Q000295:instrumentation*; D000203:Activities of Daily Living; D000369:Aged, 80 and over; D004185:Disability Evaluation; D004867:Equipment Design; D005260:Female; D005684:Gait / Q000502:physiology; D015577:Geriatric Assessment; D006801:Humans; D008124:Locomotion / Q000502:physiology*; D008297:Male; D018670:Monitoring, Ambulatory / Q000295:instrumentation*; D009043:Motor Activity / Q000502:physiology*; D011187:Posture / Q000502:physiology; D015203:Reproducibility of Results
Accelerometry; Geriatric assessment; Physical activity; Rehabilitation