STATISTICS
Analysis of the data was performed using SPSS v.17 statistical program (SPSS Inc., Chicago, IL, USA). Continuous variables were presented as mean ± standard deviation and categorical variables were expressed as number (%). Comparative analysis was conducted Mann-Whitney U and chi-square tests. Logistic regression analysis was performed to determine the independent risk factors for mortality. p≤ 0.05 is considered as statistically significant differences.