ActiGraph GT3X+ cut-points for identifying sedentary behaviour in older adults in free-living environments

Aguilar-Farías, Nicolás, Brown, Wendy J. and Peeters, G. M. E. E. (Geeske) (2014) ActiGraph GT3X+ cut-points for identifying sedentary behaviour in older adults in free-living environments. Journal of Science and Medicine in Sport, 17 3: 293-299. doi:10.1016/j.jsams.2013.07.002

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Author Aguilar-Farías, Nicolás
Brown, Wendy J.
Peeters, G. M. E. E. (Geeske)
Title ActiGraph GT3X+ cut-points for identifying sedentary behaviour in older adults in free-living environments
Journal name Journal of Science and Medicine in Sport   Check publisher's open access policy
ISSN 1440-2440
1878-1861
Publication date 2014-05-01
Year available 2013
Sub-type Article (original research)
DOI 10.1016/j.jsams.2013.07.002
Open Access Status Not yet assessed
Volume 17
Issue 3
Start page 293
End page 299
Total pages 7
Place of publication Chatswood, NSW, Australia
Publisher Elsevier Australia
Language eng
Abstract Objectives: To determine the ActiGraph GT3X+ cut-points with the highest accuracy for estimating time spent in sedentary behaviour in older adults in free-living environments. ActivPAL(3Tm) was used as the reference standard.
Formatted abstract
Objectives To determine the ActiGraph GT3X+ cut-points with the highest accuracy for estimating time spent in sedentary behaviour in older adults in free-living environments. ActivPAL3™ was used as the reference standard.

Design Cross-sectional study.

Methods 37 participants (13 males and 24 females, 73.5 ± 7.3 years old) wore an ActiGraph GT3X+ and an ActivPAL3™ for 7 consecutive days. For ActivPAL3™, variables were created based on posture. For ActiGraph GT3X+, sedentary behaviour was defined as (1) vector magnitude and (2) vertical axis counts for 1-s, 15-s and 1-min epochs, with cut-points for 1-s epochs of <1 to <10 counts, for 15-s epochs of <1 to <100 counts and for 1-min epochs of <1 to <400 counts. For each of the ActiGraph GT3X+ cut-points, area under the receiver operating characteristic curve (area under the curve), sensitivity, specificity, and percentage correctly classified were calculated. Bias and 95% limits of agreement were calculated using the Bland-Altman method.

Results The highest areas under the curve were obtained for the vector magnitude cut-points: <1 count/s, <70 counts/15-s, and <200 counts/min; and for the vertical axis cut-points: <1 count/s, <10 counts/15-s and <25 counts/min. Mean biases ranged from −4.29 to 124.28 min/day. The 95% limits of agreement for these cut-points were ±2 h suggesting great inter-individual variation.

Conclusions The results suggest that cut-points are dependent on unit of analyses (i.e. epoch length and axes); cut-points for a given epoch length and axis cannot simply be extrapolated to other epoch lengths. Limitations regarding inter-individual variability and misclassification of standing activity as sitting/lying must be considered.
Keyword Actigraphy
Sensitivity and specificity
Triaxial accelerometer
ActivPAL
ROC analysis
Q-Index Code C1
Q-Index Status Confirmed Code
Grant ID 2010002155
ID569940
Institutional Status UQ
Additional Notes Available online 8 August 2013

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2014 Collection
School of Public Health Publications
School of Human Movement and Nutrition Sciences Publications
 
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Citation counts: TR Web of Science Citation Count  Cited 43 times in Thomson Reuters Web of Science Article | Citations
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Created: Mon, 25 Nov 2013, 01:10:15 EST by Deborah Noon on behalf of School of Human Movement and Nutrition Sciences