2.2 Statistical analysis
Continuous data are expressed as the mean ± standard deviation and their
differences were evaluated using Student’s t -test. For
categorical data, the differences were evaluated using the χ2 and Fisher
exact tests. Time-to-event analyses were performed using Kaplan–Meier
estimates and compared between groups using the log-rank test.
Independent predictors of overall survival were determined using Cox
regression analysis. The multivariable models included covariates with a
p <0.10 in the univariate analyses. All statistical analyses
were performed using StatView version 5.0 software (SAS Institute, Cary,
NC). In each analysis, p <0.05 was regarded as significant.
RESULTS