RT Journal Article
SR Electronic
T1 Measuring Physical Activity in Juvenile Idiopathic Arthritis: Activity Diary Versus Accelerometer
JF The Journal of Rheumatology
JO J Rheumatol
FD The Journal of Rheumatology
SP 1249
OP 1256
DO 10.3899/jrheum.160671
VO 44
IS 8
A1 Wineke Armbrust
A1 G.J.F. Joyce Bos
A1 Jan H.B. Geertzen
A1 Pieter J.J. Sauer
A1 Pieter U. Dijkstra
A1 Otto T.H.M. Lelieveld
YR 2017
UL http://www.jrheum.org/content/44/8/1249.abstract
AB Objective. (1) To determine convergent validity of an activity diary (AD) and accelerometer (Actical brand/Phillips-Respironics) in measuring physical activity (PA) in children with juvenile idiopathic arthritis (JIA). (2) To determine how many days give reliable results. (3) To analyze effects of correcting accelerometer data for non-wear.Methods. Patients with JIA (8–13 yrs) were recruited from 3 Dutch pediatric rheumatology centers. PA was assessed for 7 days with an AD and accelerometer, and was expressed as mean min/day of rest, light PA (LPA), moderate to vigorous PA (MVPA), and PA level (PAL). To analyze convergent validity, intraclass correlation coefficients (ICC) were calculated and paired sample Student t tests were performed. The required number of days to achieve reliable results was calculated using the Spearman-Brown prophecy formula.Results. Convergent validity between AD and accelerometer was moderate for rest and PAL (ICC 0.41). ICC for LPA and MVPA were < 0.24. AD overestimated PAL and MVPA compared with the accelerometer. Wearing the accelerometer 7–19 days gave reliable PA estimates on group and individual levels. For the AD, 13–36 days were needed. Adjusting accelerometer data for non-wear resulted in a clinically relevant higher mean number of min/day spent in LPA (effect size 1.12), but not in MVPA (effect size 0.44).Conclusion. Convergent validity between AD and accelerometer is moderate to poor. In children with JIA, 1-week assessment with an accelerometer is sufficient to measure PA (all levels) reliably. On an individual level and for clinical use, 3 weeks are required. Additional use of AD enables correction for non-wear of accelerometer data.