Early Biomarker-Guided Prediction of Bloodstream Infection in Critically Ill Patients: C-Reactive Protein, Procalcitonin, and Leukocytes

Background Bloodstream infections (BSIs) often lead to critical illness and death. The primary aim of this study was to determine the diagnostic accuracy of the biomarkers C-reactive protein (CRP), procalcitonin (PCT), and leukocyte count for the diagnosis of BSI in critically ill patients. Methods This was a nested case–control study based on the Procalcitonin And Survival Study (PASS) trial (n = 1200). Patients who were admitted to the intensive care unit (ICU) Results In total, there were 525 patients (n = 175 cases, 350 controls). The fixed low threshold for all 3 biomarkers (CRP = 20 mg/L; leucocytes = 10 × 109/L; PCT = 0.4 ng/mL) resulted in negative predictive values on day 1: CRP = 0.91; 95% CI, 0.75–1.00; leukocyte = 0.75; 95% CI, 0.68–0.81; PCT = 0.91; 95% CI, 0.84–0.96). Combining the 3 biomarkers yielded similar results as PCT alone (P = .5). Conclusions CRP and PCT could in most cases rule out BSI in critically ill patients. As almost no patients had low CRP and ∼20% had low PCT, a low PCT could be used, along with other information, to guide clinical decisions.