Diagnostic and predictive performance of biomarkers in patients with sepsis in an intensive care unit

Abstract

Objective: This study was performed to compare the predictive performance of serum procalcitonin (PCT), N-terminal brain natriuretic propeptide (NT-proBNP), interleukin-6 (IL-6), prothrombin time (PT), thrombin time (TT), and Sequential Organ Failure Assessment (SOFA) score in the intensive care unit (ICU).

Methods: This retrospective cohort study enrolled 150 patients with sepsis and septic shock and 30 control patients without sepsis. Each patient was followed until death or 28 days. Correlations between variables were assessed with Spearman's rho test. The Kruskal-Wallis and Mann-Whitney U tests were used for between-group comparisons.

Results: Receiver operating characteristic curve analysis of the SOFA score, PCT, NT-proBNP, IL-6, PT, and TT showed an area under the curve of 0.872, 0.732, 0.711, 0.706, 0.806, and 0.691, respectively, for diagnosing sepsis. Binary logistic regression demonstrated that the SOFA score was an independent predictor of 28-day mortality and septic shock. The correlation coefficient (r) between SOFA and PCT, NT-proBNP and SOFA, IL-6 and SOFA, PT and SOFA, and TT and SOFA was 0.79, 0.52, 0.57, 0.56, and 0.58, respectively.

Conclusion: While the SOFA score is the gold standard, analysis of multiple biomarkers could increase the performance capacity for diagnosis and prognosis in patients with sepsis in the ICU.

Keywords: Interleukin-6; N-terminal brain natriuretic propeptide; Sequential Organ Failure Assessment score; prothrombin time; sepsis; septic shock; thrombin time.

Figure 1.

ROC curves of PCT, NT-proBNP, IL-6, PT, TT, and SOFA score for diagnosing sepsis. Areas under the ROC curve are as follows: SOFA score (red line): 0.872 (95% confidence interval (CI), 0.821–0.922), P < 0.0001; PCT (blue line): 0.732 (95% CI, 0.656–0.808), P < 0.0001; NT-proBNP (green line): 0.711 (95% CI, 0.636–0.785), P < 0.0001; IL-6 (gray line): 0.706 (95% CI, 0.629–0.782), P < 0.0001; PT (purple line): 0.806 (95% CI, 0.743–0.868), P < 0.0001; TT (yellow line): 0.691 (95% CI, 0.614–0.769), P < 0.001. ROC, receiver operating characteristic; PCT, procalcitonin; NT-proBNP, N-terminal brain natriuretic propeptide; IL-6, interleukin 6; PT, prothrombin time; TT, thrombin time; SOFA, Sequential Organ Failure Assessment score.

Figure 2.

ROC curves of PCT, NT-proBNP, IL-6, PT, TT, and SOFA score for predicting septic shock. Areas under the ROC curve are as follows: SOFA score (red line): 0.826 (95% confidence interval (CI), 0.760–0.892), P < 0.0001; PCT (blue line): 0.636 (95% CI, 0.541–0.732), P = 0.004; NT-proBNP (green line): 0.607 (95% CI, 0.515–0.699), P = 0.025; IL-6 (yellow line): 0.600 (95% CI, 0.507–0.694), P = 0.035; SOFA48h (sky blue line): 0.848 (95% CI, 0.786–0.910), P < 0.001; PT (gray line): 0.738 (95% CI, 0.657–0.816), P < 0.001; TT (yellow line): 0.600 (95% CI, 0.526–0.711), P = 0.13. ROC, receiver operating characteristic; PCT, procalcitonin; NT-proBNP, N-terminal brain natriuretic propeptide; IL-6, interleukin 6; PT, prothrombin time; TT, thrombin time; SOFA, Sequential Organ Failure Assessment score; SOFA48h, Sequential Organ Failure Assessment score at 48 hours.

Figure 3.

ROC curves of PCT, NT-proBNP, IL-6, PT, TT, and SOFA score for predicting 28-day mortality in patients with sepsis. Areas under the ROC curve are as follows: SOFA score (red line): 0.841 (95% confidence interval (CI), 0.776–0.905), P < 0.0001; PCT (blue line): 0.805 (95% CI, 0.734–0.876), P < 0.001; NT-proBNP (green line): 0.576 (95% CI, 0.477–0.675), P < 0.128; IL-6 (purple line): 0.597 (95% CI, 0.502–0.602), P = 0.05; PT (gray line): 0.542 (95% CI, 0.446–0.638), P = 0.401; TT (yellow line): 0.589 (95% CI, 0.496–0.682), P = 0.074; SOFA score at 48 h (sky blue line): 0.886 (95% CI, 0.839–0.933), P < 0.0001; qSOFA score: 0.698 (95% CI, 0.616–0.781), P < 0.001. ROC, receiver operating characteristic; PCT, procalcitonin; NT-proBNP, N-terminal brain natriuretic propeptide; IL-6, interleukin 6; PT, prothrombin time; TT, thrombin time; SOFA, Sequential Organ Failure Assessment score; SOFA48h, Sequential Organ Failure Assessment score at 48 hours

Figure 4.

Correlation of PCT, NT-proBNP, IL-6, PT, TT, and SOFA score in patients with sepsis. (a) There was a significant positive correlation between PCT and SOFA score (r = 0.79, P < .001). (b) The correlation coefficient was a significant positive correlation between NT-pro BNP and SOFA score (r = 0.52, P <. 001). (c) The correlation coefficient was a significant positive correlation between IL-6 and SOFA score (r = 0.57, P <.001). (d) There was a significant positive correlation between PT and SOFA (r = 0.56, P < .001). (e) The correlation coefficient between TT and SOFA was r = 0.58, P <.001) indicating a moderate effect size.