Table 2.
Regression based Bland–Altman 95% limits of agreement and estimated mean differences for step counts of each of three automated measures.
| Device |
|||
|---|---|---|---|
| Step-N-Tune | A4L | IDEEA | |
| RA patients | |||
| Variation in bias, per step | − 1.11x | − 0.38x | − 1.53x |
| Width of 95% LOA | 169.74 | 52.90 | 225.00 |
| Bias (95% LOA): 100 steps | 110.59 (25.72 to 195.46) | 6.12 (20.33 to 32.57) | 127.84 (15.34 to 240.34) |
| 150 steps | 55.09 (− 29.78 to 139.96) | − 12.88 (− 39.33 to 13.57) | 51.34 (− 61.16 to 163.84) |
| 200 steps | − 0.41 (− 85.28 to 84.46) | − 31.88 (− 58.33 to − 5.43) | − 25.16 (137.66 to 87.34) |
| Controls | |||
| Variation in bias, per step | 0.011x | − 0.13x | − 0.05x |
| Width of 95% LOA | 22.64 | 44.16 | 61.52 |
| Bias (95% LOA): 200 stepsa | − 6.51 (− 17.83 to 4.81) | − 20.75 (− 42.83 to 1.33) | 21.47 (− 9.29 to 52.23) |
Bias = estimated mean difference between gold standard and test device; LoA = limits of agreement; x = mean of gold standard and test device.
a
Estimates are only provided for controls at 200 steps because there were no observed data at lower step counts.