Comparison between procalcitonin and C-reactive protein as sepsis diagnostic marker

INTRODUCTION. The ideal sepsis biomarker still has to be born. The need of a useful and reliable clinical tool, nourish clinical and experimen- tal research. OBJECTIVE. Retrospective analysis of prospectively collected data to compare the clinical informative value of Procalcitonin (PCT) and C-Reactive protein (CPR) plasma concentrations in the detec- tion of infection and sepsis and in the assessment of severity of sepsis in a medico-sukrgical intensive care unit (ICU). METHODS. We collected all clinical data, drug administration, scores and PCT values of 927 consecutive adult patients who were admitted to the intensive care unit for an expected stay >48hours. PCT and PCR plasma concentrations were measured daily during the intensive care unit stay. Each patient was exam- ined daily for signs and symptoms of infection and was classified daily in one of the following six categories: negative, localized infection, systemic inflammatory response syndrome (SIRS), sepsis, severe sepsis or septic shock. The severity of sepsis-related organ failure was assessed by the sepsis-related organ failure assess- ment (SOFA) score. RESULTS. A total of 8538 patient days were classified into the six categories. The median plasma PCT concentrations in each class was respectively: negative 0.62 ng/ml, localized infection: 0.69 ng/ml, SIRS: 2.29 ng/ml, sepsis: 4.34 ng/ml, severe sepsis 17.30 ng/ml and septic shock 26.80 ng/ml. The median plasma PCR concentrations in each class were negative 49.6 mg/dl, localized infection 68.6 mg/dl, SIRS 86.3 mg/dl, sepsis 125.6 mg/dl, severe sepsis 154.4 mg/dl and septic shock 183.5 mg/dl. The linear correlation between PCT plasma concentrations and the six categories was much stronger than in the case of PCR (Spearman ́s rho, 0.668 vs. 0.489; p< 0.0001). The area under the receiver operating characteristic curve was 0.846 for PCT (95% CI, 0.838-0.854), compared with 0.751 for PCR (95% CI 0.742-0.760) (p < 0.0001). CONCLUSIONS. PCT is a better marker of sepsis than PCR. The course of PCT shows a closer correlation than PCR with the severity of infec- tion and organ dysfunction.