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.