Table 2.
Agreement in step counts between X6 accelerometer and wrist-worn devices.
|
Group |
FBTa | GARb | ||||||||
|
n |
ρ (P value) |
Differencec
(IQR)d |
Error (IQR) |
P; PU/Le |
n |
ρ (P value) |
Difference (IQR) |
Error (IQR) |
P; PU/L |
|
| All participants | 36 | .78 (<.001) | 463 (−220 to 924) |
32.9% (8.3-52.5) |
.002; .99 | 33 | .65 (<.001) | 963 (59-1390) |
40.9% (14.9-69.5) |
.008; break/>.99 |
| No gait aid | 13 | .97 (<.001) | −203 (−288 to 339) |
10.3% (5.5-30.4) |
.85; .32 | 11 | .56 (.07) | −561 (−1960 to 971) |
23.1% (14.7-46.1) |
.28; break/>0.77 |
| Rollator | 15 | .42 (.12) | 926 (386-1939) |
52.3% (39.9-56.9) |
.01; .99 | 15 | .30 (.27) | 1390 (283-2376) |
67.2% (26.2-73.0) |
.001; break/>>.99 |
| Single-point cane | 8 | .98 (<.001) | 406 (−18 to 912) |
12.6% (5.8-22.3) |
.08; .90 | 7 | .93 (.003) | 963 (377-1330) |
21.3% (15.0-41.1) |
.02; break/>.99 |
aFBT: Fitbit Charge HR.
bGAR: Garmin Vivosmart.
cThe difference is calculated as the X6 accelerometer step count minus the wrist device step count; therefore, a positive value means the wrist-worn device undercounted, whereas a negative value means the wrist-worn device overcounted.
dIQR: interquartile range
dP values are for Wilcoxon signed rank tests: two-sided to compare median step counts of the devices and one-sided testing of whether the median difference is significantly different from a lower (PL) and upper (PU) limit (the greater of the 2 is reported).