Assessment of continuous neutrophil CD64 index measurement for diagnosing sepsis and predicting outcome in a Chinese pediatric intensive care unit: a prospective study

BACKGROUND: The high affinity immunoglobulin-Fc fragment receptor I CD64 on neutrophils is widely assumed to be a useful biomarker in the early identification of sepsis, and it improves outcomes. We aimed to determine its ability to diagnose sepsis and predict its prognosis with continuous measurements. METHODS: A total of 335 patients admitted to a Chinese PICU were prospectively stratified into two groups according to the presence of sepsis (defined by clinical criteria for sepsis) between 2018 and 2019. Serum concentrations of the nCD64 index, C-reactive protein (CRP), and procalcitonin (PCT) were measured. Sensitivity, specificity and receiver operating characteristic (ROC) curves were calculated to evaluate the diagnostic value for sepsis. A multiple logistic regression model was used to estimate the prognostic value of continuous nCD64 index measurement for in-hospital death. RESULTS: The baseline nCD64 index and levels of PCT and CRP were significantly higher in septic children than in nonseptic children (P<0.05). The nCD64 index presented a higher sensitivity (0.90), specificity (0.78) and area under the ROC curve [0.91 (0.90, 0.93)] than CRP and PCT in discriminating septic children with an optimal cutoff value of 5.78. The nCD64 index decreased with the progression of sepsis, and the baseline nCD64 index was strongly associated with in-hospital death (OR: 2.18, 95% CI: 1.02–4.74). Moreover, the more rapidly the nCD64 index declined, the lower the in-hospital death rate was (OR: 0.89, 95% CI: 0.63–1.35) after adjusting for the baseline nCD64 index and other confounders. CONCLUSIONS: The nCD64 index was not only effective for the early diagnosis of childhood sepsis but also positively associated with the prognosis of sepsis. Moreover, the nCD64 decline was inversely associated with the in-hospital death rate.