Statistical analysis
Descriptive analyses were performed to provide information on general characteristics of the study population. Visual (probability plots, histograms) and analytical methods (Kolmogorov-Simirnov/Shapiro-Wilk’s test) were used to determine whether they are normally distributed or not. Descriptive analyses were presented using medians and interquartile range (IR) for the non-normally distributed variables. The Mann-Whitney U Test was used for nonparametric tests, Independent Sample T Test was used for parametric tests to compare these parameters. Chi-square test used to compare the categorical variables between two groups. The categorical variables were presented as the frequency (% percentage). The performance of midkine was assessed using receiver operating characteristic (ROC) curve analysis and by calculating the area under the curve (AUC) of the ROC curves. A p-value <0.05 was considered significant. Analyses were performed using SPSS statistical software (IBM SPSS Statistics, Version 22.0. Armonk, NY: IBM Corp.)