RH14
Comparability of Output from Actigraph Accelerometer Models 7164 and GT3X+ in Youth with Multiple Sclerosis

Thursday, May 25, 2017
B2 (New Orleans Convention Center)
Danusha Nandamalavan, BSc, CCRA , Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, ON, Canada
Samantha Stephens, PhD , Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, ON, Canada
Stephanie A Grover, MSc, CCRP , Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, ON, Canada
Dominique Kinnett-Hopkins, BSc , Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign, Urbana, IL
Marcia Finlayson, PhD, OT Reg (Ont), OTR , School of Rehabilitation Therapy, Queen's University, Kingston, ON, Canada
Robert W Motl, PhD , Physical Therapy, University of Alabama at Birmingham, Birmingham, AL
E. Ann Yeh, MD, MA, FRCPC, Dip ABPN , Neurology, The Hospital for Sick Children, Toronto, ON, Canada
Danusha Nandamalavan, BSc, CCRA , Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, ON, Canada
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Background: Accelerometers provide valid and reliable physical activity (PA) measurements in children. Older versions of accelerometers have become obsolete due to upgrades in technology. The comparability of output from older versions with newly upgraded accelerometers has not been studied in youth with Multiple Sclerosis (MS). This has implications for the interpretation of data specifically from longitudinal studies that have employed both devices to collect PA data. 

Objectives: To determine the level of consistency between minutes spent in sedentary, light, moderate, vigorous, moderate-vigorous (MVPA) activity using ActiGraph 7164 and GT3X+ accelerometers in youth with MS.

Methods: Youth with a diagnosis of MS were recruited at The Hospital for Sick Children in Toronto, Canada. Youth wore the 7164 and GT3X+ accelerometers simultaneously for 7 days. Time spent in sedentary, light, moderate, vigorous, MVPA activity was calculated. Consistency between time spent at different intensities were analyzed by intra-class correlation coefficients (ICC) with 95% confidence intervals (CI). Mean differences and limits of agreement were also calculated and visualized using Bland-Altman plots. Ethics approval was obtained.

Results: 17 youth (16.65(3.03)y.o., F=12) were included in the analysis. The average number of valid days was 5.56±1.58. The agreement and consistency between the two devices were: sedentary (mean difference=2.31 min/day, ICC=0.91, 95% CI 0.76-0.96), light (mean difference=-3.06 min/day, ICC=0.91, 95% CI 0.78-0.96), moderate (mean difference=5.46 min/day, ICC=0.93, 95% CI 0.83-0.97) and MVPA (mean difference=5.16/day, ICC=0.92, 95% CI 0.82-0.97) intensity. Poor consistency (mean difference=-0.32 min/day, ICC=0.45, 95% CI 0.01-0.75) was found between the devices for activities that were vigorous in nature. The removal of an outlier improved the consistency between the devices for vigorous intensity (mean difference=-0.02 min/day, ICC=0.90, 95% CI 0.76-0.96) and remained unchanged across the other intensities (ICC range=0.90-0.93). 

Conclusions: Results suggest sufficient consistency between ActiGraph 7164 and GT3X+ for time spent in sedentary, light and vigorous intensity levels in youth with MS. Despite comparable output, large mean differences and wide limits of agreement for minutes of moderate and MVPA indicate poor agreement between the two devices. Further work will investigate if this is ameliorated with a correction factor.

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