2.1 | Statistical analysis
Statistical analysis was conducted with SPSS 20 (SPSS, Chicago, IL).
Kolmogorov-Smirnov test was used to determine the normality of
distribution. Continuous variables were expressed as mean ± SD or median
(25-75 IQR) and compared with Student t test or Mann-Whitney U test
according to the distribution. Categorical variables were expressed as
number and percentages and compared with chi-square or Fisher’s exact
chi-square test. Multivariate logistic regression analysis with backward
elimination was used to determine the independent predictors of
mortality. Receiver operating characteristics (ROC) curve was performed
to determine the area under curve (AUC) of variables for predicting
mortality. The comparison of the AUCs were performed with Delong test. Ap value of less than 0.05 was considered as statistically
significant.