Statistical Analysis
Data are presented as mean and standard deviation (SD) if numerical and
as count and percentages if categorical. Normality was assessed using
Shapiro-Wilk test. Continuous numerical variables have been compared
using the Student t-test, while categorical variables have been compared
with chi-square test or Fisher exact test as appropriate. Time to event
analysis has been conducted using Log-rank test and displayed with
Kaplan-Meier curves. Univariable and Multiple Cox proportional Hazard
models were run to identify potential factors affecting mid-term
survival with hazard ratios (HR) and confidence intervals (CI). The
final multivariable model was obtained using those variables that had a
significant p-value at the univariable analysis with backward/forward
selection based on AIC. Alpha error was set at 0.05 for significance and
all tests are two-sided. The statistical analysis was conducted with R
version 3.6.0 (2019-04-26; R Core Team (2019). R: A language and
environment for statistical computing. R Foundation for Statistical
Computing, Vienna, Austria. URLhttps://www.R-project.org/.)