Another New Way to Risk Stratify Febrile Infants

July 2, 2019

Written by Clay Smith

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Infants ≤60 days with no fever in the ED, normal urinalysis, and ANC <5185 had low probability for invasive bacterial infection (IBI).

Why does this matter?
We have talked much about febrile infants and risk stratification with the Step-by-Step and PECARN study. This is another take on this theme. It is slightly different and informs us about something new, infants with no fever in the ED but reported at home.

Score! Febrile infants for the win
This was a multicenter case-control study of febrile infant ≤60 days who were not ill appearing. They identified 181 infants with IBI (86% bacteremia; 14% meningitis) and 362 matched control infants who also had fever but did not have IBI. Using multiple logistic regression, they found four risk factors for IBI.

• Age <21 days (1 point)

• Highest temperature recorded in the ED 38.0-38.4°C (2 points) or ≥38.5°C (4 points)

• Absolute neutrophil count (ANC) ≥5185 cells per μL (2 points)

• Abnormal urinalysis results (3 points)

A score ≥2 had sensitivity 98.8%, specificity 31.3%. The authors concluded, “Infants ≤60 days old with fever by history only, a normal urinalysis result, and an absolute neutrophil count <5185 cells per μL have a low probability of IBI.” There is a major caveat – this is a case-control with clinical variables gleaned from chart review. A clinical decision rule needs prospective external validation before we put it into practice. Regardless, this is encouraging and can inform us as we take care of these patients. Editorialist Nate Kuppermann laments there is no unified way to evaluate these patients but offers a view into the future noting, “gene expression analysis using RNA biosignatures…may potentially replace prediction algorithms.” Won’t that be a welcome change!

Source
A Prediction Model to Identify Febrile Infants ≤60 Days at Low Risk of Invasive Bacterial Infection. Pediatrics. 2019 Jun 5. pii: e20183604. doi: 10.1542/peds.2018-3604. [Epub ahead of print]

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