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Immature neutrophils in young febrile infants
  1. Sriram Ramgopal1,
  2. Lorne W Walker1,
  3. Andrew J Nowalk1,
  4. Andrea T Cruz2,
  5. Melissa A Vitale1
  1. 1 Department of Pediatrics, UPMC Children’s Hospital of Pittsburgh, University of Pittsburgh, School of Medicine, Pittsburgh, Pennsylvania, USA
  2. 2 Department of Pediatrics, Texas Children’s Hospital, Baylor College of Medicine, Houston, Texas, USA
  1. Correspondence to Dr. Sriram Ramgopal, Division of Pediatric Emergency Medicine, Department of Pediatrics, UPMC Children’s Hospital of Pittsburgh, University of Pittsburgh School of Medicine, Pittsburgh, PA 15224, USA; sriram.ramgopal{at}


Background To describe the diagnostic value of the absolute band count (ABC) and ratio of immature to total neutrophils (I:T) for invasive bacterial infections (IBIs; bacterial meningitis and bacteraemia) among young febrile infants.

Methods We performed a cross-sectional study in a paediatric emergency department of febrile infants ≤60 days over 12 years to evaluate the accuracy of the ABC and I:T for IBI.

Results Of 2930 included patients, 75 (2.6%) had IBIs. The area under the curve (AUC; 95% CI) for ABC was 0.69 (0.62 to 0.76) with sensitivity 0.27 (0.17 to 0.38) and specificity 0.94 (0.93 to 0.95) at cutoff ≥1500 cells/µL. The AUC for I:T was 0.65 (0.59 to 0.72) with sensitivity 0.29 (0.19 to 0.41) and specificity 0.88 (0.87 to 0.89) at cutoff ≥0.2. Only the ABC in infants 29–60 days was minimally accurate.

Conclusion The ABC and I:T were generally inaccurate for detecting IBI in febrile infants. Guidelines without these parameters may be better for risk assessment.

  • infectious diseases

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  • Contributors SR designed the study, performed the analysis and drafted the manuscript. LWW designed the study, acquired the data, interpreted the data and revised the manuscript for important intellectual content. ATC, MAV and AJN designed the study and revised the manuscript for important intellectual content. All authors provide final approval of the version to be published and agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

  • Funding This project was supported in part by the National Institutes of Health through Grant Number UL1-TR-001857.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Patient consent for publication Not required.

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