Table 2.
Reliability and correlation analysis for pooled data set of torso and thigh features across all FTSS tests
| Torso sensor | Thigh sensor | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Variable name | Technical name | ICC (95% CI) | MMSEρ | BBSρ | ICC (95% CI) | MMSEρ | BBSρ | ||
| TotalTime | Time to complete FTSS | 0.86 | (0.82−0.90) | −0.11 | −0.26 | 0.86 | (0.81−0.89) | −0.09 | −0.39 |
| MeanSSSTime | Mean sit-stand-sit time | 0.74 | (0.67−0.80) | −0.15 | −0.47 | 0.50 | (0.35−0.62) | −0.08 | −0.42 |
| CVSSSTime | Coefficient of variation of sit-stand-sit time | 0.30 | (0.10−0.47) | −0.06 | −0.17 | 0.57 | (0.45−0.67) | 0.12 | −0.01 |
| NumReps | Number of sit-to-stand transitions completed | 0.84 | (0.80−0.88) | 0.00 | 0.15 | 0.83 | (0.79−0.87) | 0.09 | 0.07 |
| MeanStandTime | Mean time to stand-up | 0.83 | (0.78−0.87) | −0.11 | −0.40 | 0.36 | (0.17−0.51) | 0.07 | −0.17 |
| CV_StandTime | Coefficient of variation of stand time | 0.50 | (0.35−0.61) | −0.09 | −0.22 | 0 | (0−0.21) | −0.01 | −0.09 |
| MeanSitTime | Mean time to sit down | 0.58 | (0.46−0.68) | −0.14 | −0.43 | 0.39 | (0.21−0.53) | 0.08 | 0.01 |
| CV_SitTime | Coefficient of variation of sit time | 0.30 | (0.10−0.47) | −0.03 | −0.16 | 0.33 | (0.14−0.49) | 0.10 | −0.01 |
| Fmed_Acc | Median frequency acceleration | 0.71 | (0.62−0.78) | 0.08 | 0.25 | 0.54 | (0.41−0.65) | 0.09 | 0.15 |
| SEF_Acc | Spectral edge frequency acceleration | 0.66 | (0.56−0.74) | 0.10 | 0.15 | 0.74 | (0.66−0.80) | 0.07 | 0.15 |
| H_Acc | Spectral entropy acceleration | 0.70 | (0.62−0.77) | −0.01 | −0.19 | 0.80 | (0.74−0.85) | 0.11 | 0.14 |
| Fmed_AngVel | Median frequency angular velocity | 0.65 | (0.55−0.74) | 0.24 | 0.19 | 0.78 | (0.72−0.84) | 0.13 | 0.21 |
| SEF_AngVel | Spectral edge frequency angular velocity | 0.73 | (0.65−0.80) | 0.12 | 0.14 | 0.78 | (0.71−0.83) | 0.06 | 0.12 |
| H_AngVel | Spectral entropy angular velocity | 0.67 | (0.57−0.75) | 0.10 | −0.01 | 0.81 | (0.75−0.85) | 0.09 | 0.01 |
| AccZ_stand_start_mean | Mean Z-axis acceleration at stand-start | 0.87 | (0.83−0.90) | 0.21 | 0.16 | 0.91 | (0.88−0.93) | −0.14 | −0.35 |
| AccZ_sit_end_mean | Mean Z-axis acceleration at sit-end | 0.85 | (0.81−0.89) | 0.08 | 0.15 | 0.91 | (0.89−0.93) | −0.14 | −0.35 |
| AccZ_mid_stand_mean | Mean Z-axis acceleration at mid-stand | 0.65 | (0.54−0.73) | −0.07 | −0.04 | 0.95 | (0.94−0.96) | −0.12 | −0.27 |
| AccZ_stand_start_std | Std. dev. of Z-axis acceleration at stand-start | 0.60 | (0.48−0.69) | 0.07 | 0.03 | 0.78 | (0.71−0.83) | 0.08 | 0.07 |
| AccZ_sit_end_std | Std. dev. of Z-axis acceleration at sit-end | 0.56 | (0.44−0.67) | 0.04 | 0.06 | 0.73 | (0.65−0.79) | −0.05 | 0.06 |
| AccZ_mid_stand_std | Std. dev. of Z-axis acceleration at mid-stand | 0.56 | (0.44−0.67) | 0.07 | 0.01 | 0.76 | (0.69−0.82) | 0.05 | 0.04 |
| AV_X_stand_start_mean | Mean X-axis angular velocity at stand-start | 0.89 | (0.85−0.91) | −0.11 | −0.11 | ||||
| AV_X_sit_end_mean | Mean X-axis angular velocity at sit-end | 0.67 | (0.58−0.75) | 0.12 | 0.27 | ||||
| AV_X_mid_stand_mean | Mean X-axis angular velocity at mid-stand | 0.31 | (0.10−0.47) | 0.05 | 0.11 | ||||
| AV_X_stand_start_std | Std. dev. of X-axis angular velocity at stand-start | 0.65 | (0.54−0.73) | −0.01 | 0.01 | ||||
| AV_X_sit_end_std | Std. dev. of X-axis angular velocity at sit-end | 0.63 | (0.53−0.72) | 0.07 | −0.03 | ||||
| AV_X_mid_stand_std | Std. dev. of X-axis angular velocity at mid-stand | 0.62 | (0.51−0.71) | 0.01 | 0.14 | ||||
| RMS_X_Total_Acc | Root mean square acceleration (X) | 0.94 | (0.92−0.95) | −0.12 | 0.08 | ||||
| RMS_Y_Total_Acc | Root mean square acceleration (Y) | 0.90 | (0.88−0.93) | 0.12 | 0.09 | ||||
| RMS_Z_Total_Acc | Root mean square acceleration (Z) | 0.93 | (0.91−0.95) | 0.18 | 0.18 | ||||
| Jerk_X_Total_Acc | Jerk acceleration (X) | 0.50 | (0.36−0.62) | 0.04 | −0.13 | ||||
| Jerk_Y_Total_Acc | Jerk acceleration (Y) | 0.42 | (0.25−0.56) | −0.05 | −0.01 | ||||
| Jerk_Z_Total_Acc | Jerk acceleration (Z) | 0.47 | (0.32−0.60) | 0.07 | 0.08 | ||||
| RMS_X_Total_AV | Root mean square angular velocity (X) | 0.94 | (0.92−0.95) | 0.03 | 0.00 | ||||
| RMS_Y_Total_AV | Root mean square angular velocity (Y) | 0.91 | (0.89−0.93) | 0.06 | 0.05 | ||||
| RMS_Z_Total_AV | Root mean square angular velocity (Z) | 0.96 | (0.95−0.97) | 0.06 | 0.20 | ||||
| Jerk_X_Total_AV | Jerk angular velocity (X) | 0.15 | (0.09−0.35) | 0.03 | 0.04 | ||||
| Jerk_Y_Total_AV | Jerk angular velocity (Y) | 0.31 | (0.11−0.47) | 0.09 | 0.07 | ||||
| Jerk_Z_Total_AV | Jerk angular velocity (Z) | 0.44 | (0.27−0.57) | 0.15 | 0.32 | ||||
Note. ICC(2,k) with 95% confidence intervals and Spearman’s rank correlations against MMSE (MMSEρ) and BBS (BBSρ) are reported.
Abbreviations: BBS, Berg balance scale; MMSE, Mini-Mental State Examination.