TY - JOUR
T1 - ActiGraph GT3X+ cut-points for identifying sedentary behaviour in older adults in free-living environments
AU - Aguilar-Farías, Nicolás
AU - Brown, Wendy J.
AU - Peeters, G. M.E.E.Geeske
N1 - Funding Information:
The authors would like to thank the participants for the time and effort given to this study and Robert Hill for his research assistance. The work was funded by a University of Queensland Early Career Researcher Grant (ECR16; ID 2010002155) and a National Health and Medical Research Council Program grant (ID569940).
PY - 2014/5
Y1 - 2014/5
N2 - 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 <10counts, for 15-s epochs of <1 to <100counts and for 1-min epochs of <1 to <400counts. 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.
AB - 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 <10counts, for 15-s epochs of <1 to <100counts and for 1-min epochs of <1 to <400counts. 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.
UR - http://www.scopus.com/inward/record.url?scp=84899641071&partnerID=8YFLogxK
U2 - 10.1016/j.jsams.2013.07.002
DO - 10.1016/j.jsams.2013.07.002
M3 - Article
C2 - 23932934
AN - SCOPUS:84899641071
SN - 1440-2440
VL - 17
SP - 293
EP - 299
JO - Journal of Science and Medicine in Sport
JF - Journal of Science and Medicine in Sport
IS - 3
ER -