Graphing and statistical analysis
Data were presented as Mean ± SD. GraphPad Prism 5.0 (GraphPad, San
Diego, CA) was used to generate bar graphs and ROC curves. The
statistical significance of differences between groups was determined by
the Student’s t-test (two-tailed). Correlations between variables were
determined by Spearman’s correlation coefficient. Differences were
considered significant at a P value < 0.05.