Table 1:
Accuracy and Precision of the ActiGraph GT3X+ device worn on the wrist while walking at comfortable speed over-ground and on a treadmill in Parkinson’s disease and controls.
| Absolute Accuracy | Absolute Precision | Relative Accuracy | Relative Accuracy | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Mean (SD) Total Step Counts | Mean Difference in Step Counts | SD of the Mean Difference in Step Counts | Mean (SD) Percentage Error | n≥5% error | n≥10% error | n≥25% error | Coefficient of Variation | ||
| PD (n=29) | Over-Ground Walking | ||||||||
| Manually Counted | 630 (53) | ||||||||
| Less Affected Wrist ActiGraph | 569 (103) | 62 | 114 | 9.3 (16.6) | 7 | 6 | 5 | 0.08 | |
| More Affected Wrist ActiGraph | 598 (58) | 32 | 68 | 4.7 (9.1) | 6 | 5 | 1 | 0.04 | |
| Treadmill Walking | |||||||||
| Manually Counted | 663 (63) | ||||||||
| Less Affected Wrist ActiGraph | 587 (79) | 76 | 86 | 11.0 (12.0) | 15 | 10 | 3 | 0.09 | |
| More Affected Wrist ActiGraph | 597 (63) | 66 | 66 | 9.6 (9.1) | 18 | 8 | 3 | 0.07 | |
| Controls (n=31) | Over-Ground Walking | ||||||||
| Manually Counted | 621 (49) | ||||||||
| Dominant Wrist ActiGraph | 564 (76) | 57 | 83 | 8.8 (12.5) | 14 | 9 | 3 | 0.07 | |
| Non-Dominant Wrist ActiGraph | 560 (81) | 61 | 87 | 9.5 (13.4) | 11 | 10 | 6 | 0.08 | |
| Treadmill Walking | |||||||||
| Manually Counted | 647 (58) | ||||||||
| Dominant Wrist ActiGraph | 546 (101) | 1010 | 102 | 15.2 (15.4) | 20 | 16 | 8 | 0.13 | |
| Non-Dominant Wrist ActiGraph | 533 (97) | 114 | 113 | 17.0 (16.5) | 21 | 16 | 9 | 0.15 | |