Isolating out-of-bed wear from non-wear and in-bed wear periods in young adults hip-worn accelerometer data (continuous wear protocol)

  • Presented on 2015

Background: The published literature shows no automated method valid for isolating adults out-of-bed wear in continuously worn (24h/day) accelerometer data. We developed an automated algorithm (AA) for continuous hip-worn protocol Actigraph (GT3X+) data that separates out-of-bed wear from in-bed wear and non-wear periods.

Methods: In 95 participants of the Raine study (mean±SD, 21.9±0.57 years, 54% female), we examined agreement with a referent method (i.e., ‘getting into’ and ‘getting out’ of bed times visually identified by two independent raters, R1 and R2).

Results: The mean difference (AA – R1) in out-of-bed wear was 7 min/day (95% Limits of Agreement: 220 to 234 min) on days valid by both methods. Agreement for the classification of each minute as out-of bed wear (yes/no) was excellent (κ > 0.75) for 89% of participants (AA vs R1) and poor (κ<0.4) for only 1%, with a median κ=0.86, comparable to the agreement between raters R1 and R2 (median κ= 0.94). Here, the AA performed better than previous algorithms validated in children (median κ =0.77) and adolescents (κ =0.66) in our dataset. Agreement in classification as in-bed wear (yes/no) for AA vs R1 was excellent for only 51% of participants (median κ =0.80). Out-of-bed minutes were identified as such 94% of the time while 9% and 11% of in-bed worn minutes were classified as nonwear and out-of-bed wear, respectively.

Discussion: The algorithm is useful and better than existing automated alternatives, for isolating out-of-bed wear but requires improvement to specifically isolate in-bed wear periods.


  • Joanne McVeigh 1
  • Elisabeth Winkler 2
  • Genevieve Healy 2
  • James Slater 3
  • Peter Eastwood 3
  • Leon Straker 1


Department of Physiotherapy and Exercise Science, Curtin University, Australia
The University of Queensland, School of Population Health, Brisbane, Australia
School of Anatomy, Physiology and Human Biology, University of Western Australia

Presented at



, ,