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.)