Neutrophil CD64, C-reactive protein, and procalcitonin in the identification of sepsis in the ICU - Post-test probabilities

Purpose We were interested in whether C-reactive protein (CRP) and procalcitonin (PCT) distinguish sepsis from non-septic controls and whether a combination of CRP, PCT, and neutrophil CD64 improves identification of sepsis in the intensive care unit (ICU). Materials and methods We analyzed the CRP and PCT concentrations from 27 patients with sepsis and 15 ICU controls. In addition, CD64 on neutrophils was measured using quantitative flow cytometry. We present a multiple marker analysis for sepsis diagnostics combining neutrophil CD64, CRP, and PCT using post-test analysis. Results The CRP and PCT values separated sepsis and non-septic ICU patients. In post-test analysis, CRP provided a positive probability of 0.48 and a negative probability of 0.053 for sepsis in the ICU; while, the corresponding values were 0.35 and 0.0059, respectively, for PCT and 0.62 and 0.0013, respectively, for neutrophil CD64. When neutrophil CD64 was analyzed with PCT and CRP, the probabilities were 0.98 and Conclusions Neutrophil CD64 expression was superior to PCT and CRP for the identification of sepsis in ICU. Positive post-test probability for any combinations of simultaneously analyzed CRP, PCT and CD64 showed improved diagnostic accuracy for sepsis. This approach may be useful for guiding antibiotic treatment in ICU.