Can we rely on the neutrophil left shift for the diagnosis of neonatal sepsis? Need for re-evaluation

Abstract

BackgroundNeonatal sepsis cause significant morbidities and mortality among affected neonates. The gold standard for its diagnosis is the blood culture. However, its usefulness is limited by many factors. A rapid diagnostic test with high sensitivity and specificity is needed for rapid identification of neonatal sepsis without exposing unaffected neonates to antibiotic therapy. The accuracy of immature neutrophil count for the diagnosis of neonatal sepsis is controversial. ObjectiveBeing rapid, simple and readily available, this study aimed to re-evaluate the usefulness of neutrophil left shift for the diagnosis of neonatal sepsis and assess its prognostic value in reflecting the patients’ outcome. MethodsThis prospective cross-sectional study included 285 neonates admitted to the neonatal intensive care unit, Cairo University. Demographic, clinical and laboratory data were collected including complete blood pictures with manual differentials and blood culture results. The diagnostic accuracy of neutrophil left shift was done through applying multiple logistic regression and receiver operating characteristic [ROC] curve. ResultsAmong the study group, 61.4% had definite sepsis while 12.3% had probable sepsis. The median immature to total neutrophil ratio (I/T ratio) was 0.25, IQR 0.21, range 0.03–0.8. I/T ratio ≥ 0.2 was present in 65.6% of the patients and had significantly increased odds of infection, sensitivity (82.4%), specificity (81.3%), positive predictive value (92.5%) and negative predictive value (62.2%). By plotting neutrophil left shift against blood culture, total white blood cell count (WBC) and platelet count in a ROC curve and calculating areas under the curve (AUC), it proved to be a good diagnostic test (AUC: 0.861) while total WBC count (AUC: 0.515) and platelet count (AUC: 0.366) had poor diagnostic accuracy. ConclusionNeutrophil left shift is a rapid, simple and readily available test that has a reasonable positive predictive value and specificity which denotes its usefulness in the early diagnosis of neonatal sepsis as well as in decreasing the exposure of non-septic neonates to antimicrobial therapy.