The correlation between procalcitonin, C-reactive protein and severity scores in patients with sepsis and their value in assessment of prognosis

Abstract

To investigate the correlation between procalcitonin (PCT), C-reactive protein (CRP) and acute physiology and chronic health evaluation II (APACHE II) score and sequential organ failure assessment (SOFA) score, and to investigate the value in assessment of PCT and CRP in prognosis in patients with sepsis. Clinical data of patients admitted to intensive care unit (ICU) of Changzheng Hospital Affiliated to the Second Military Medical University from January 2011 to June 2014 were retrospectively analyzed. 201 sepsis patients who received PCT and CRP tests, and evaluation of APACHE II score and SOFA score were enrolled. The values of PCT, CRP, APACHE II score and SOFA score between survivals (n = 136) and non-survivals (n = 65) were compared. The values of PCT and CRP among groups with different APACHE II scores and SOFA scores were compared. The relationships between PCT, CRP and APACHE II score and SOFA score were analyzed by Spearman correlation analysis. Receiver operating characteristic (ROC) curve was plotted to assess the prognostic value of PCT and CRP for prognosis of patients with sepsis. Compared with survival group, the values of PCT [μg/L: 11.03 (19.17) vs. 1.39 (2.61), Z = -4.572, P < 0.001], APACHE II score (19.16±5.32 vs. 10.01±3.88, t = -13.807, P < 0.001) and SOFA score (9.66±4.28 vs. 4.27±3.19, t = -9.993, P < 0.001) in non-survival group were significantly increased, but the value of CRP was not significantly different between non-survival group and survival group [mg/L: 75.22 (110.94) vs. 56.93 (100.75), Z = -0.731, P = 0.665]. The values of PCT were significantly correlated with APACHE II score and SOFA score (r1 = 0.373, r2 = 0.392, both P < 0.001), but the values of CRP were not significantly correlated with APACHE II score and SOFA score (r1 = -0.073, P1 = 0.411; r2 = -0.106, P2 = 0.282). The values of PCT rose significantly as the APACHE II score and SOFA score became higher, but the value of CRP was not significantly increased. When APACHE II score was 0-10, 11-20, and > 20, the value of PCT was 1.45 (2.62), 1.96 (9.04), and 7.41 (28.9) μg/L, respectively, and the value of CRP was 57.50 (83.40), 59.00 (119.70), and 77.60 (120.00) mg/L, respectively. When SOFA score was 0-5, 6-10, and > 10, the value of PCT was respectively 1.43 (3.09), 3.41 (9.75), and 5.43 (29.60) μg/L, and the value of CRP was 49.30 (86.20), 76.00 (108.70), and 75.60 (118.10) mg/L, respectively. There was significant difference in PCT between any two groups with different APACHE II and SOFA scores (P < 0.05 or P < 0.01), but no significant differences in CRP were found. The area under the ROC curve (AUC) of PCT for prognosis was significantly greater than that of CRP [0.872 (95% confidence interval 0.811-0.943) vs. 0.512 (95% confidence interval 0.427-0.612), P < 0.001]. When the cut-off value of PCT was 3.36 μg/L, the sensitivity was 66.8%, and the specificity was 45.4%. When the cut-off value of CRP was 44.50 mg/L, the sensitivity was 82.2%, and the specificity was 80.3%. Compared with CRP, PCT was more significantly correlated with APACHE II score and SOFA score. PCT can be a better indicator for evaluation of degree of severity, and also prognosis in sepsis patients.