Statistical Analysis
The normality of the distribution of continuous variables was tested using the Shapiro-Wilk test. Student’s t-test (for normal data) or the Mann-Whitney U test (for non-normal data) were used to compare two independent groups. The Chi-square test was used to investigate the relationship between categorical variables. Receiver operating characteristics (ROC) curve analysis was performed to determine the diagnostic values of some numerical measurements.
Discrimination of the model was graded according to the area under the ROC curve, as follows: 0.5-0.6 = fail discrimination, 0.6-0.7 = poor discrimination, 0.7-0.8 = acceptable discrimination, 0.8-0.9 = good discrimination, 0.9-1 = excellent discrimination. Statistical analysis was performed using the SPSS for Windows version 24.0 software and P-values <0.05 were accepted as statistically significant.