2.7 Statistics analysis
SPSS version 23 software (SPSS Inc., Chicago, Illinois) was used for statistical analysis. Data is expressed as means ± standard deviation for continuous variables and as frequencies and percentages for categorical variables. Baseline characteristics and outcomes were compared using the chi-square test for categorical variables and the T-student test for continuous variables. Cox regression analysis was used to calculate the hazard ratio (HR) and 95% confidence intervals (CI) of events. Kaplan–Meier survival function and the log-rank test were used to compare the survival distributions. A value of p<0.05 was considered statistically significant.
RESULTS