Division of Health and Human Physiology, College of Liberal Arts and Sciences, University of Iowa, Iowa City, IA.
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Comparison of Two Generations of ActiGraph Accelerometers: The CARDIA Study
- Published on Jun 2018
Purpose: This study aimed to examine the comparability of the ActiGraph 7164 and wGT3X-BT wear time, count-based estimates, and average time per day in physical activity of different intensities.
Methods: We studied 87 Coronary Artery Risk Development in Young Adults (CARDIA) participants 48-60 yr of age who simultaneously wore the 7164 and wGT3X-BT accelerometers at the waist in 2015-2016, with wear time of ≥4 of 7 d, ≥10 h·d for both monitors. Freedson cutpoints (counts per minute) were used to define sedentary (<100), light (100-1951), moderate (1952-5724), and vigorous activity (≥5725). Agreement was evaluated using paired-difference tests, intraclass correlation coefficients, and Bland-Altman plots. Given systematic differences in count-based estimates between monitors, a calibration formula applied to the wGT3X-BT values was obtained by linear regression.
Results: Total detected wear time minutes per day was nearly identical between the 7164 and the wGT3X-BT (881.5 ± 70.9 vs 880.3 ± 78.1, P = 0.72). The wGT3X-BT values were calibrated to the 7164 values by dividing counts by 1.088. After calibration, no differences were observed between the 7164 and the wGT3X-BT in total counts per day (310,184 ± 129,189 vs 307,085 ± 135,362, P = 0.48), average counts per min per day (349.5 ± 139.5 vs 346.5 ± 147.2, P = 0.54), sedentary (513.2 ± 93.6 vs 509.6 ± 98.6, P = 0.23), light (335.3 ± 81.5 vs 338.7 ± 81.1, P = 0.22), moderate (31.0 ± 21.9 vs 30.3 ± 23.4, P = 0.31), or moderate-to-vigorous minutes per day (33.1 ± 24.6 vs 32.0 ± 26.0, P = 0.13). A significant difference was observed for vigorous minutes per day (0.2 ± 1.0 vs 0.0 ± 0.3, P < 0.01); however, the absolute difference was marginal. Intraclass correlation coefficients showed excellent agreement for all measures (0.95-0.99).
Conclusions: After applying a calibration formula, the 7164 and wGT3X-BT were comparable for total wear time, count-based estimates, and average minutes per day in sedentary, light, moderate, and moderate-to-vigorous activity. Findings illustrate a novel methodological approach to facilitate accelerometer data harmonization.
- Whitaker KM 1
- Pettee Gabriel K 2
- Jacobs DR Jr 3
- Sidney S 4
- Sternfeld B 5
Department of Epidemiology, Human Genetics, and Environmental Sciences, School of Public Health-Austin Campus, University of Texas Health Science Center at Houston, Austin, TX Department of Women's Health, Dell Medical School, University of Texas at Austin, Austin, TX.
Division of Epidemiology and Community Health, School of Public Health, University of Minnesota, Minneapolis, MN.
Division of Research, Kaiser Permanente, Oakland, CA.
Medicine and Science in Sports and Exercise