Statistical analysis
All statistical analysis was carried out using SPSS v. 22.0 . Continuous variables were represented by median (interquartile range, IQR). Classification variables were represented by frequency. Mann-Whitney rank sum test was used to compare the non-normally distributed data. Logistic regression was used for correlation analysis. The area under the curve was calculated by the ROC of the subjects. Bilateral significance level was set at P<0.05.