Funding sources The SWET study was funded by the National Institute for Health Research (NIHR) Health Technology Assessment (HTA) programme (05/16/01). The views and opinions expressed in this article are those of the authors and do not necessarily reflect those of the NIHR HTA programme. Pilot work was supported through a grant from Nottingham University Hospitals Trust.
Are accelerometers a useful tool for measuring disease activity in children with eczema? Validity, responsiveness to change, and acceptability of use in a clinical trial setting
Article first published online: 13 SEP 2012
© 2012 The Authors. BJD © 2012 British Association of Dermatologists
British Journal of Dermatology
Volume 167, Issue 5, pages 1131–1137, November 2012
How to Cite
Wootton, C.I., Koller, K., Lawton, S., O’Leary, C., Thomas, K.S. and on behalf of the SWET study team (2012), Are accelerometers a useful tool for measuring disease activity in children with eczema? Validity, responsiveness to change, and acceptability of use in a clinical trial setting. British Journal of Dermatology, 167: 1131–1137. doi: 10.1111/j.1365-2133.2012.11184.x
Conflicts of interest None declared.
Trial registration: Current Controlled Trials ISRCTN71423189.
- Issue published online: 29 OCT 2012
- Article first published online: 13 SEP 2012
- Accepted for publication 17 June 2012
Background Actigraphy, which uses accelerometers to record movement, has been proposed as an objective method of itch assessment in eczema. Previous studies have found strong correlations with actigraphy and video surveillance, disease severity and biological markers in patients with eczema.
Objectives To assess the validity of accelerometer data, its responsiveness to change and the practicality and acceptability of accelerometers when used as an outcome measure in a clinical trial.
Methods This study used data collected from 336 participants of the Softened Water Eczema Trial (SWET). Accelerometer data were compared with three standardized scales: Six Area, Six Sign Atopic Dermatitis (SASSAD) severity score, Patient Oriented Eczema Measure (POEM) and Dermatitis Family Impact (DFI). Spearman’s rank testing was used for correlations.
Results Only 70% of trial participants had complete data, compared with 96% for the primary outcome (eczema severity – SASSAD). The convergent validity of accelerometer data with other measures of eczema severity was poor: correlation with SASSAD 0·15 (P = 0·02) and POEM 0·10 (P = 0·13). Assessing for divergent validity against quality of life measures, the correlation with the DFI was low (r = 0·29, P < 0·0001). Comparing the change scores from baseline to week 12 for SASSAD, POEM and DFI with the change in accelerometer scores we found low, negative correlations (r = −0·02, P = 0·77; r = −0·12, P = 0·06; and r = −0·01, P = 0·87, respectively). In general, the units were well tolerated but suggestions were made that could improve their usability in children.
Conclusions Actigraphy did not correlate well with disease severity or quality of life when used as an objective outcome measure in a multicentre clinical trial, and was not responsive to change over time. Further work is needed to establish why this might be, and to establish improved methods of distinguishing between eczema-related and eczema-nonrelated movements.