Statistical analysis
Continuous numeric variables were expressed as mean ± SD or medians
(IQR), and compared with a two-sample t test and one-way analysis of
variance (for normally distributed data), or Mann-Whitney test and
Kruskal-Wallis test (for non-normal distribution of data). Categorical
variables were expressed as frequency number (%), and compared using χ
2 test or Fisher’s exact test. Survival curves were obtained by the
Kaplan-Meier analysis and compared using log-rank test. Receiver
operator characteristics (ROC) analysis was undertaken to compute the
best predictive threshold of significant biomarker elevation for
mortality prediction. Estimations of mortality predictors were performed
using univariate and multivariate Cox regression models. All statistical
calculations were performed using MedCalc Statistical Software version
19.2 (MedCalc Software, Ostend, Belgium; http://www.medcalc.org; 2020).