Statistical analysis
Statistical analyses were performed using SPSS software version 22.0 for Windows. Data were presented as means with standard deviations (SDs) or medians with interquartile ranges (IQRs). The Mann–Whitney U test was used to compare non-parametric variables and Student’s t -test and one-way analysis of variance (ANOVA) testing were used for parametric data. Correlations between DUS parameters and clinical scores were assessed with Spearman’s rank correlation coefficient. Cut-off values of predictors were calculated using a receiver operating characteristic (ROC) curve. Values of p < 0.05 were considered statistically significant.