# Portable RGB-D Camera-Based System for Assessing Gait Impairment Progression in ATTRv Amyloidosis
## 3 Results  
Regarding the gait parameter computation over the 3D joint data provided by the RGB-D camera, our approach requires only an average of 0.65 s to extract the considered parameters for a given gait cycle (including cycle detection). This result was obtained using a computer with an Intel(r) Core(tm) i7-4600U CPU 2.1-2.7 GHz and 8 GB RAM. Table 3 shows the mean difference results obtained for each parameter, patient, and system. In this table, a statistically significant difference of the parameter's value between T0 and T1 (\(p\)-value \(\leq\) 0.001) is indicated with \"\(\downarrow\)\" or \"\(\uparrow\)\" next to the mean difference value (negative or positive difference, respectively). For each parameter and patient, the mean difference values for the reference and RGB-D camera systems are highlighted in grey where a non-significant difference was detected for both, or when there was a significant difference and the trend (positive or negative) was the same for both. Overall, the systems showed similar performance for 53 out of 82 cases in terms of spatiotemporal parameters, and 18 out of 48 cases for kinematic parameters. There was agreement for most patients in the case of the six spatiotemporal parameters; all patients for stride duration, gait speed, and arm swing velocity; five patients for stride length and foot swing velocity; and four patients for gait speed variability. For the remaining spatiotemporal parameters, there was agreement between the systems for half of the patients (stance duration, step length and width, and TBCM-V) or less (2 patients for step, single and double support duration, and TBCM-ML; 1 patient for swing duration). For the  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{ \begin{tabular}{c} Spatiotemporal \\ Gait Parameter \\ \end{tabular}  } & \multicolumn{6}{c}{**Mean Difference (T1–T0)**} \\ \cline{2-13}  & \multicolumn{2}{c}{**P1**} & \multicolumn{2}{c}{**P2**} & \multicolumn{2}{c}{**P3**} & \multicolumn{2}{c}{**P4**} & \multicolumn{2}{c}{**P5**} & \multicolumn{2}{c}{**P6**} \\ \cline{2-13}  & **Ref** & **RGB-D** & **Ref** & **RGB-D** & **Ref** & **RGB-D** & **Ref** & **RGB-D** & **Ref** & **RGB-D** & **Ref** & **RGB-D** \\ \hline
**Stride duration (s)** & 0.026 & 0.022 & 0.074 & 0.086 & 0.0804 & -0.0834 & -0.0834 & -0.0834 & -0.087 & -0.076 & 0.0817 & 0.0817 \\ Step duration (s) & 0.012 & 0.009 & 0.039 & 0.038 & -0.026 & -0.025 & -0.043 & -0.051 & -0.030 & -0.041 & 0.030 & 0.031 \\ Stance duration (s) & 0.025 & 0.019 & 0.0381 & 0.0541 & -0.0438 & 0.0641 & -0.118 & -0.045 & -0.0611 & -0.043 & 0.027 & 0.027 \\ Swing duration (s) & 0.000 & 0.003 & 0.0287 & 0.013 & -0.0211 & -0.005 & 0.048 & -0.012 & -0.005 & -0.033 & 0.032 & 0.033 \\ Single support & 0.000 & 0.0135 & 0.0447 & 0.015 & -0.0501 & 0.004 & 0.079 & -0.045 & -0.016 & -0.0651 & 0.0837 & 0.0871 \\ Double support & & & & & & & & & & & & \\ duration (s) & 0.026\(\uparrow\) & 0.009 & 0.019 & 0.030 & -0.014 & -0.0641 & -0.021 & -0.0501 & -0.010 & -0.0184 & -0.014 \\ Stride length (cm) & -11.27 & -12.11 & -16.5 & -17.12 & -13.05 & -0.081 & 1.46 & 0.091 & -11.94 & 11.271 & 1.68 & -3.64 \\ Step length (cm) & -6.20 & -6.22 & -7.49 & -8.997 & -0.356 & 0.946 & 3.36 & 2.99 & - & 1.51 & -3.98 \\ Step width (cm) & -1.761 & -0.495 & -1.26 & -1.037 & -0.042 & 1.09 & 1.39 & 0.45 & - & 0.853 & 0.897 \\ Gait speed (ms) & -1.0314 & -0.182 & -0.1854 & -0.1031 & 0.009 & 0.027 & 0.033 & 0.128 & -0.1361 & -0.068 & -0.069 \\29 cases where there was no agreement, the following was observed: the RGB-D sensor was unable to detect an actual significant difference fourteen times; it incorrectly detected a significant difference seven times; a significant difference was detected correctly but the trend over time was opposite eight times. For kinematic parameters, the Kinect was in accordance with Qualisys for half of the patients for the spine shoulder and the maximum and minimum elbow angle, and only two or one patient for the remaining parameters.