Measuring Physical Activity in Juvenile Idiopathic Arthritis: Activity Diary Versus Accelerometer

Armbrust, W., Bos, G. J. F. J., Geertzen, J. H. B., Sauer, P. J. J., Dijkstra, P. U. & Lelieveld, O. T. H. M. 1-Apr-2017 In : The Journal of Rheumatology. 44, 6

Research output: Scientific - peer-reviewArticle


  • Measuring Physical Activity in Juvenile Idiopathic Arthritis

    Final publisher's version, 851 KB, PDF-document


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.

Original languageEnglish
JournalThe Journal of Rheumatology
Issue number6
StatePublished - 1-Apr-2017


  • Journal Article

View graph of relations

ID: 42158960