Defining a valid day of accelerometer monitoring in adults with mental illness

Chapman, Justin J., Brown, Wendy J. and Burton, Nicola W. (2015) Defining a valid day of accelerometer monitoring in adults with mental illness. Mental Health and Physical Activity, 9 48-54. doi:10.1016/j.mhpa.2015.09.003

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Author Chapman, Justin J.
Brown, Wendy J.
Burton, Nicola W.
Title Defining a valid day of accelerometer monitoring in adults with mental illness
Journal name Mental Health and Physical Activity   Check publisher's open access policy
ISSN 1755-2966
Publication date 2015-10
Year available 2015
Sub-type Article (original research)
DOI 10.1016/j.mhpa.2015.09.003
Open Access Status File (Author Post-print)
Volume 9
Start page 48
End page 54
Total pages 30
Place of publication Amsterdam, The Netherlands
Publisher Elsevier
Collection year 2016
Language eng
Formatted abstract
A valid day of accelerometry is commonly defined as an absolute duration of wear time. Data processing inconsistencies can arise when using absolute valid-day criteria for adults with varied waking hours. The aim was to compare the use of absolute and relative valid-day criteria in a sample of adults with mental illness.

Data were from 99 non-institutionalised adults with mental illness. Participants were asked to wear an ActiGraph GT3X+ accelerometer continuously for seven days, and to note sleep and non-wear times. Absolute valid-day criteria were defined as a set number of hours/day, and relative criteria as a proportion of waking hours. The mean waking duration, non-wear time, and time spent in physical activity (PA) and sedentary behaviour (SB), were derived from accelerometer data, and compared for a range of absolute and relative criteria. The potential inaccuracy of PA and SB estimates were also estimated.

Use of absolute criteria systematically biased the sample toward those with longer waking hours, and resulted in a median of 86% (IQR=47% to 198%) more non-wear time than relative criteria. The potential inaccuracy of SB was from -2.5% to 0% with relative criteria, and from -2.2% to 10.6% for absolute criteria.

For participant samples with varied waking hours, such as adults with mental illness, a valid-day criterion should be based on the proportion of waking hours, rather than the absolute time. The specific valid-day criterion should be chosen for each study independently, and be accompanied with a measure of the non-wear time.
Keyword Accelerometry
Activity measurement
Data processing
Data management
Data reduction
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2016 Collection
School of Human Movement and Nutrition Sciences Publications
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Created: Wed, 14 Oct 2015, 12:02:42 EST by Sandrine Ducrot on behalf of School of Human Movement and Nutrition Sciences