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.