RESULTS
Table 1 includes the demographic and clinical characteristics of groups 1 and 2. The number of cases with a GRACE score higher than 140 was statistically higher in group 2 than in group 1. When comparing echocardiography and laboratory parameters for each group, it was evident that SYNTAX scores and copeptin levels were significantly higher in group 2 (copeptin: 9.4 vs 28.8 pmol/l, p<0.001; SYNTAX score: 8 vs 24, p <0.001). Other examined parameters were similar across both groups (see Table 2).
Serum copeptin levels were significantly higher in patients with ST segment depression than in those with normal ECG results (13.7 vs 26.9 pmol/l, p<0.001). Serum copeptin levels were higher in the group with SYNTAX scores above 32 and lower in the group with scores below 23; all paired comparisons were found to be statistically significant for the 3 SYNTAX score category. (SYNTAX score<23 vs SYNTAX score 23-32; 11.6 pmol/l vs 30.5 pmol/l, P<0.001; SYNTAX score<23 vs SYNTAX score >32; 11.6 pmol/l vs 40.9 pmol/l, p<0.001, SYNTAX score 23-32 vs SYNTAX score >32; 30.5 pmol/l vs 40.9 pmol/l, p<0.001; see Figure 2). Similarly, serum copeptin levels were significantly higher among those with GRACE scores above 140 than among those with lower GRACE scores (GRACE score<109 vs GRACE score>140; 12.6 pmol/l vs 27pmol/l, p<0.001; and GRACE score 109-140 vs GRACE score>140; 15.8pmol/l vs 27pmol/l, p:0.002; see Figure 2). The paired comparison of the group with GRACE scores below 109 and the group with GRACE scores between 109 and 140 was statistically similar (12.6 pmol/l vs 15.8pmol/l, p:0.114; see Figure 2).
When examining the correlation between serum copeptin levels and CAD severity, there was a high level of positive correlation between copeptin levels and SYNTAX scores (r:0.683, p value <0.001). When the serum copeptin level was used as a predictor of high SYNTAX scores with a threshold of 18.3 pmol/l, diagnostic sensitivity was found to be 74.7%, specificity was 83.8%, the positive predictive value was 80.7%, the negative predictive value was 78.6%, and the area under the curve was 0.795 (see Figure 3).