Statistical analyses
Descriptive statistics were calculated for the baseline demographic and
clinical features and treatment outcomes. Graphical and mathematical
methods tested the normality of distribution. As appropriate, continuous
variables were presented as means with standard deviations or medians
with 25th-75th percentiles.
Categorical variables were presented as numbers and percentages.
Differences between groups were analysed using Student’s t-test for
continuous variables (or the Mann-Whitney test) and the Pearson
chi-squared test for categorical variables. Survival analysis was
performed using the Kaplan-Meier method, and the groups were compared
using the log-rank test. In addition, Kaplan-Meier survival curves were
truncated at a timepoint in follow-up, when at least 10% of patients
were still at risk, to avoid visual misinterpretation.(13) The
significance level was set at 0.05, and all testing was two-sided.
Statistical analysis was performed using the IBM SPSS Statistics for
Windows, version 21.0. (Armonk, NY, USA) package.