Statistical analysis
Descriptive statistics are expressed as median, mean, standard deviation, minimum and maximum values, and interquartile ranges (IQR). Student’s t -test was used for parametric variables that were normally distributed, and a Welch’s t -test or a Mann–WhitneyU test was used for non-parametric variables that were non-normally distributed. Fisher’s exact test was applied for small samples of categorical variables. All tests were two-sided, andp -values of <0.05 were considered significant. Bootstrap resampling with random computer-generated iterations was applied in cases of n = 0.