Statistical Analysis
Statistical analysis was performed with R software, version 3.6.0 (R
Foundation for Statistical Computing, Vienna, Austria). Continuous data
were expressed as the mean ± standard deviation for normally distributed
variables or as medians (interquartile ranges) for non-normally
distributed variables according to the Shapiro-Wilk test, and categoric
data were expressed as count (percentage). Comparisons between
continuous variables were made using Student’s t -test for
normally distributed data or the Wilcoxon rank-sum test for non-normally
distributed data based on the Shapiro-Wilk test. Categoric variables
were compared using a chi-squared test. When ≥20% of expected counts
were ≤5, however, Fisher’s exact test was used.