Statistical analysis
Demographic and baseline clinical data were summarized by descriptive
statistics with Excel (Microsoft, Redmond, WA, USA). Normally
distributed continuous variables were presented as mean ± standard
deviation (SD); non-normally distributed ones were described as median
and interquartile range (IQR). Categorical variables were expressed as
percentage. The Mann-Whitney U and Pearson v2 tests were used to compare
continuous and categorical variables, respectively. Long-term survival
odds in patients with categorical and continuous baseline risks were
evaluated by the Kaplan-Meier method; the patients lost to follow-up
were counted as censored. Median follow-up was determined by the reverse
censoring method. P < 0.05 indicated statistical significance.
Statistical analyses were performed with SPSS 21.0 for Windows (IBM Co.,
Armonk, NY, USA).