Statistical analyses
The analyses were performed on JMP 9.0 software (SAS Inc., Cary, NC, USA). Continuous data were presented as median and standard deviation (SD) or interquartile range (IQR). Categorical data were reported as frequencies and percentages. Comparisons used the χ2 or Fisher’s exact test for categorical variables and Student’s t test or Mann–Whitney–Wilcoxon test, when appropriate, for continuous variables. Survival curves were calculated using the Kaplan-Meier method. A two-tailed p-value <0.05 was considered statistically significant.