Early detection of severe sepsis in the emergency room: Diagnostic value of plasma C-reactive protein, procalcitonin, and interleukin-6

Objectives: To determine the diagnostic values of plasma C-reactive protein (CRP), procalcitonin (PCT), and interleukin-6 (IL-6) using an electrochemiluminescence immunoassay (ECLIA) method (Roche Diagnostics GmbH, Mannheim, Germany) to identify severe sepsis in an emergency room (ER) setting. Methods: This was a single-centre prospective follow-up study of 539 consecutive adult patients admitted to the ER with suspected infection. Blood samples were taken concurrently with blood cultures at admission. Patients were divided into 5 groups on the basis of systemic inflammatory response syndrome (SIRS) criteria, documentation of bacterial infection, and organ dysfunction. Fifty-nine patients with no SIRS or bacterial infection, 68 patients with bacterial infection but no SIRS, 54 patients with SIRS but no bacterial infection, 309 patients with sepsis (SIRS and bacterial infection), and 49 patients with severe sepsis (sepsis and organ failure) were evaluated. Results: In a logistic regression model, the odds ratio (OR) for PCT was 1.58 (95% confidence interval (CI) 1.37-1.82, p < 0.0001), for IL-6 was 1.54 (95% CI 1.32-1.80, p < 0.0001), and for CRP was 1.33 (95% CI 1.01-1.75, p = 0.045). The area under the curve (AUC) was 0.77 (95% CI 0.71-0.84) for PCT, 0.72 (95% CI 0.64-0.80) for IL-6, and 0.60 (95% CI 0.51-0.69) for CRP. PCT emerged as the best marker for severe sepsis, but the difference in AUC was not significant between PCT and IL-6. In multivariate logistic regression analysis, after adjusting for confounders, PCT and IL-6 remained significant independent predictors of severe sepsis. Conclusions: PCT and IL-6 proved superior to CRP in detecting patients with severe sepsis. The findings thus support the use of either PCT or IL-6 as an early tool to diagnose severe sepsis. The automatic ECLIA method allows even night-shift measurements.