Objectives: To determine the correlations and predictive strength of surrogate markers (body temperature, leukocyte count, C-reactive protein (CRP) and procalcitonin (PCT)) with elevated levels of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) in septic patients on randomly chosen days.
Design: Prospective consecutive case series.
Setting: Surgical intensive care unit (ICU) of a university hospital.
Patients: Two hundred forty-three patients experiencing ICU stays of longer than 48 h categorized for sepsis according to ACCP/SCCM Consensus Conference criteria.
Measurements and main results: CRP and PCT were both significantly correlated with TNF-alpha and IL-6. Based on the area under the curve (AUC) of the receiver operating characteristic (ROC) curves, predictive capability was highest for PCT (0.846 for TNF-alpha>40 pg/ml and 0.837 for IL-6>500 pg/ml), moderate with CRP (0.744 and 0.748, respectively), and lowest for leukocyte count (0.562 and 0.534, respectively) and body temperature (0.570 and 0.623, respectively). Sensitivity, specificity, positive and negative predictive values and test effectiveness all followed this same pattern of being highest for PCT followed by CRP, with leukocyte count and body temperature being lowest.
Conclusion: PCT may be an early and better marker of elevated cytokines than the more classic criteria of inflammation.