2.4. Statistical Analysis
PAD
Between-group comparisons were analyzed using the Mann–Whitney U test (nonparametric data). Paired analysis was performed by Wilcoxon test (nonparametric data). The chi-squared test was used to compare categorical data. Statistical analyses were performed using SPSS statistical software version 20, and Graph Pad Prism version 6. Data are expressed as medians with interquartile ranges and percentages. Absolute differences in some parameters were calculated using mean values. For specific group analysis, the absolute number is also expressed in brackets. 