Statistical analysis.

Differences between the two groups were assessed by the Student’s unpaired t-test for all parametric data, by the Mann-Whitney U test for non-parametric data. These quantitative data were expressed as the mean ± standard deviation (SD). Differences between the two groups for categorical data was performed using the Chi-Square test. These data are represented as the number of patients in the category followed by the percentage of the group total, as n (%). Statistical analysis was performed using SPSS version 21 (IBM SPSS, Armonk, NY). A p-value <0.05 was considered statistically significant.