Statistical analysis
Data were statistically analyzed using SPSS 23.0 and MedCalc 16.2. Data were expressed as mean ± SD or as d number (percentage). Difference of variance was calculated by a variance ratio test (F-test). To compare continuous variables, we used the independent sample t test. For categorical variables, we applied the Chi-square test.
The Inter- and intra-observer reproducibility of LUSS was assessed by using Bland-Altman plot, with a coefficient of variation, Pearson’s correlation, and intra-class correlation coefficient (ICC). The coefficient of variation was defined as the standard deviation of differences between two readings in the percentage of the mean. P values < 0.05 were considered statistically significant.