Table 5.
Relative and absolute reliability of steps, assessed with ActivPAL3™, SENS motion®, and direct observations.
| Comparison | Mean (SD) of both assessments (steps) | Mean (SD) difference (steps) | p value for difference | ICC2.1 (95% CI) | SEM (SEM%) | MDC95 (MDC%) |
|---|---|---|---|---|---|---|
| ActivPAL vs. observed | ||||||
| All, N = 35 | 183.3 (82.2) | -75.5 (49.1) | <0.001 | 0.609 (-0.086-0.865) | 51.4 (28) | 142.5 (78) |
| Slow walkers, n = 21 | 137.4 (71.2) | -94.1 (50.9) | <0.001 | 0.439 (-0.095-0.791) | 53.3 (39) | 147.7 (107) |
| Fast walkers, n = 14 | 252.3 (40.0) | -47.5 (30.5) | <0.001 | 0.468 (-0.110-0.820) | 29.2 (12) | 80.9 (32) |
| SENS vs. observed | ||||||
| All, N = 35 | 193.4 (78.6) | -55.3 (39.3) | <0.001 | 0.717 (-0.043-0.909) | 41.8 (22) | 115.9 (60) |
| Slow walkers, n = 21 | 151.5 (70.1) | -65.9 (42.5) | <0.001 | 0.596 (-0.093-0.870) | 44.6 (29) | 123.6 (82) |
| Fast walkers, n = 14 | 256.3 (38.3) | -39.5 (28.4) | <0.001 | 0.523 (-0.106-0.845) | 26.5 (10) | 73.5 (29) |
| ActivPAL vs. SENS | ||||||
| All, N = 35 | 155.7 (88.5) | -20.1 (34.8) | 0.002 | 0.905 (0.758-0.957) | 27.3 (18) | 75.7 (49) |
| Slow walkers, n = 21 | 104.4 (73.4) | -28.3 (41.4) | 0.005 | 0.803 (0.451-0.925) | 32.6 (31) | 90.4 (89) |
| Fast walkers, n = 14 | 232.6 (40.0) | -8.0 (16.5) | 0.1 | 0.906 (0.723-0.969) | 12.3 (5) | 34.1 (15) |
ICC: intraclass correlation coefficient; SEM: standard error of measurement (SD of mean [both assessments] × √1 − ICC); MDC: minimal detectable change (SEM × √2 × 1.96, SEM% = 100 × SEM/mean). SEM and MDC indicate measurement error (in sec) at group and individual levels, respectively. Slow walkers: <0.67 m/s; fast walkers: ≥0.67 m/s. ActivPAL: ActivPAL3™ monitor; SENS: SENS motion®.