Ratio of Neutrophilic CD64 and Monocytic HLA-DR: A Novel Parameter in Diagnosis and Prognostication of Neonatal Sepsis

Objective: Approaches to monitoring of sepsis have traditionally relied upon the pro-inflammatory component of the sepsis response. This study evaluated the diagnostic and prognostic potential of the ratio of neutrophilic CD64 (nCD64) and monocytic HLA-DR (mHLA-DR) median fluorescence index in monitoring of neonatal sepsis. Methods: Blood from 100 neonates suspected of sepsis and 29 healthy controls was collected on clinical suspicion of sepsis, and the expression of nCD64, mHLA-DR was evaluated by Flow Cytometry; thereby, a derived parameter "Sepsis index," SI=nCD64/mHLA-DR x 100 was estimated. Results: At day 1, sensitivity and specificity to detect sepsis using nCD64 was 73.01% and 89.18%, respectively, while for SI it was 73.01% and 72.22%, respectively. On Kaplan-Meier analysis, neonates with SI> cut-off showed a higher 30 day-mortality than those with low SI (P=0.096). On multivariate analysis, the factor associated with mortality in our cohort was Apgar score <= 3, while SI showed a trend toward significance. Conclusions: At day1, nCD64 is useful for the diagnosis of neonatal sepsis whereas mHLA-DR is beneficial for monitoring patients at a later time point. The SI is a marker of moderate diagnostic sensitivity and supplements the current arsenal of laboratory investigations to detect neonatal sepsis. As a marker of prognosis, a high SI shows a trend towards greater mortality. (C) 2015 Clinical Cytometry Society