Spss software package for windows version 13.0

Continuous variables with normal distribution were expressed as mean ± standard deviation (SD) and those without normal distribution as median and the range between the first and the third quartile. Discrete variables were expressed as frequencies and percentages. Statistical comparison of patient characteristics was performed using the Chi-square or the Fisher's exact test for categorical variables, and the Student's t -test or the Mann-Whitney U -test for continuous variables. Independent predictors of HSV pneumonia and 15-day mortality were investigated by a backward stepwise logistic regression model of multivariable analysis where every variable with a P -value < 0.1 at univariable analysis had been included. The area under the receiver-operating characteristic (ROC) curve, with 95% confidence interval (CI), and the Hosmer-Lemeshow test were calculated to assess the discriminatory power and the calibration of the models, respectively. The accuracy of prediction was defined as low (AUC = 0.5-0.7), moderate (AUC = 0.7-0.9), and high (AUC = 0.9-1). All tests were two-sided with the alpha level set at 0.05 for statistical significance. Data analyses were performed using the SPSS software package for Windows, version 13.0 (SPSS, Inc., Chicago, Illinois, US).