Statistical Analysis
Statistical analysis of the data was done using the IBM SPSS Statistics
Version 20.0 (SPSS Inc., Chicago, IL, USA) software package. Descriptive
data are shown as n and percentages in the categorical data fields and
as median interquartile range values in the continuous data fields. A
chi-square test was used to compare categorical data. Measured data were
tested using Kolmogorov-Smirnov tests to confirm an assumption of normal
distribution. Mann-Whitney U tests and Kruskal-Wallis tests were used
when appropriate to compare measurement data that did not show normal
distribution. A Spearman correlation analysis was used to assess the
correlation between the two sets of measured data. The threshold value
for predictability of the prevalence of CAD (the SYNTAX score) of serum
copeptin levels was determined using a receiver operating characteristic
curve (ROC) analysis. P<0.05 was accepted for statistical
significance in all analyses.