*2.3. Statistical Analysis*

The distribution of categorical variables is given with the absolute number and the relative number as a percentage. The distribution of continuous variables, such as age or length of stay, is described as medians with interquartile (IQR) ranges. Unless otherwise stated, the Chi-squared test was used to test for significant differences between the study and control groups for categorical variables and the Mann–Whitney U test was used for continuous variables, as they were not normally distributed. Data were entered using Microsoft Office Excel 2016 for Windows 10 (Version 1805, Microsoft Corporation, Redmond, WA, United States). All statistical analyses were performed with IBM SPSS Statistics Version 25 (Armonk, New York, NY, United States). Statistical significance was considered at a *p* value smaller than 0.05. Graphs were created using Microsoft Office Excel 2016 for Windows 10 (Version 1805, Microsoft Corporation, Redmond, WA, United States).
