Automated measurement of neutrophil CD64 expression for diagnosing sepsis in critically ill patients.

BACKGROUND: Although early identification of sepsis improves outcome, prompt and correct diagnostic remains often challenging. The expression of the high affinity immunoglobulin-Fc fragment receptor I CD64 on neutrophils is upregulated during acute inflammation. We here aimed at determining the usefulness of its rapid measurement in diagnosing sepsis. METHODS: Seventy-two consecutive patients were enrolled upon admission to Intensive Care Unit within a two-month period. Sequential determination of serum C-reactive protein (CRP) and procalcitonin (PCT) concentrations was obtained. The neutrophil CD64 index was measured using Accellix-CD64 (R) device, an in vitro diagnosis system allowing for an automatic and standardized measure. RESULTS: Serum concentrations of CRP and PCT as well as the neutrophil CD64 index were higher in septic patients compared to all others (P<0.05 for the three markers). Only CD64 index was an independent predictor of sepsis, though with modest sensitivity and specificity (78% and 70%, respectively). Repeat determination of CD64 index at day 2 correctly classified 85% of patients. CONCLUSIONS: This prospective study demonstrates the moderate performance of the neutrophil CD64 index, assessed through the Accellix-CD64 (R) device, in diagnosing sepsis in the critically ill patient. However, repeat measurements improve its accuracy and may help to predict ICU-acquired infections.