Data analysis
Demographics and clinical variables are reported with descriptive analysis in the overall population and according to the outcome of hospital mortality. In particular, categorical data were reported as numbers and percentages; median with interquartile range [IQR] is used to report continuous data as most of them were not normally distributed according to Kolgomorov-Smirnoff test and/or Q-Q plot inspection. Missing values were not included in the analyses. Data imputation was not carried out due to the presence of data missing not at random.
Categorical variables were analyzed using Fisher’s exact test. Continuous variables were analyzed with Mann-Whitney tests. Due to the small sample size, no multivariate analysis or regression were conducted to correct for confounders. All statistical tests were two-sided and were performed using the SPSS software (IBM SPSS Statistics® for Windows, Version 25.0. Armonk, NY: IBM Corp. ).