Objective: To investigate the correlation of procalcitonin (PCT), interleukin-6 (IL-6) and antithrombin III (AT III) with the severity of sepsis, and to compare the predictive value of the above indicators alone or in combination.
Methods: A retrospective cohort study was conducted. Eighty-five patients with sepsis admitted to the department of intensive care medicine of Shandong Provincial Hospital Affiliated to Shandong First Medical University from April 2021 to September 2022 were enrolled. General information, sequential organ failure assessment (SOFA) score and acute physiology and chronic health evaluation II (APACHE II) score within 24 hours of admission, inflammatory indicators [PCT, IL-6, serum amyloid A (SAA), neutrophil to lymphocyte ratio (NLR), and C-reactive protein (CRP)] and coagulation indicators (D-dimer and AT III) levels at admission, and 28-day prognosis were collected. The differences of the above indicators were compared among patients with different prognosis at 28 days and different severity of sepsis. The correlation between PCT, IL-6, AT III and the severity of sepsis was analyzed by Spearman rank correlation method. Receiver operator characteristic curve (ROC curve) was drawn to evaluate the predictive value of PCT, IL-6 and AT III alone or in combination on the 28-day death of patients with sepsis.
Results: Eighty-five patients were enrolled finally, 67 cases survived and 18 cases died at 28 days. The mortality was 21.2%. There were no statistical significant differences in gender, age and other general data between the two groups. The patients in the death group were more serious than those in the survival group, and PCT, IL-6, and CRP levels were significantly higher than those in the survival group [PCT (μg/L): 4.34 (1.99, 14.42) vs. 1.17 (0.31, 3.94), IL-6 (ng/L): 332.40 (50.08, 590.18) vs. 61.95 (31.64, 194.20), CRP (mg/L): 149.28 (75.34, 218.60) vs. 83.23 (48.22, 174.96), all P < 0.05], and AT III activity was significantly lower than that in the survival group [(53.67±28.57)% vs. (80.96±24.18)%, P < 0.01]. However, there were no significant differences in D-dimer, NLR and SAA between the two groups. Among the 85 patients, 36 had sepsis with single organ dysfunction, 29 had sepsis with multiple organ dysfunction, and 20 had septic shock with multiple organ dysfunction. With the increase of the severity of sepsis, PCT and IL-6 levels gradually increased [PCT (μg/L): 0.36 (0.19, 1.10), 3.00 (1.22, 9.94), 4.34 (2.18, 8.86); IL-6 (ng/L): 43.99 (20.73, 111.13), 100.00 (45.37, 273.00), 332.40 (124.4, 693.65)], and the activity of AT III decreased gradually [(89.81±21.42)%, (71.97±24.88)%, and (53.50±25.41)%], all with statistically significant differences (all P < 0.01). Spearman rank correlation analysis showed that PCT and IL-6 levels in sepsis patients were significantly positively correlated with the severity of the disease (r values were 0.562 and 0.517, respectively, both P < 0.01), and AT III activity was significantly negatively correlated with the severity of the disease (r = -0.523, P < 0.01). ROC curve analysis showed that PCT, IL-6, and AT III alone or in combination had some predictive value for the death of sepsis patients at 28 days. The area under the ROC curve (AUC) of the above three indicators in combination was higher than that of the individual tests (0.818 vs. 0.722, 0.725, and 0.770), with a sensitivity of 83.3% and a specificity of 73.1%.
Conclusions: PCT, IL-6, and AT III were significantly correlated with the severity of sepsis patients. The combined assay of the above three indicators can effectively improve the prediction of the prognosis of sepsis patients.