Welcome to Facts on the Ground a new series brought to you by Nancy Rixe, Pediatric Emergency Medicine fellow from the University of Pittsburgh. Facts on the Ground is designed to be a concise literature review that helps answer common clinical questions.

This particular paper is a modern-classic, and many of you may have already identified how it changes your practice. This is a good opportunity to review a practice changing paper.

The Article

Validation of the “Step-by-Step” Approach in the Management of Young Febrile Infants
Gomez et al.
Pediatrics, 2016

Objective

To prospectively validate the Step-by-Step approach and compare it with the Rochester criteria and the Lab-score in the identification of febrile infants ≤90 days who are at low-risk for invasive bacterial infection (IBI) as defined by the isolation of a bacterial pathogen in a blood or cerebrospinal fluid culture.

Study Design

Prospective cohort study of infants ≤90 days with fever without a source who presented to 11 European pediatric emergency departments between September 2012 and August 2014. Infants were excluded in the following circumstances: a clear source of fever was identified after a careful medical history and/or physical examination, there was no fever on arrival at the PED and the fever had been only subjectively assessed by parents on touch, without the use of a thermometer, there was an absence of 1 or more of the mandatory ancillary tests, or refusal of the parents or caregiver to participate.

All patients underwent a urine dipstick, a urine culture collected by an aseptic technique (bladder catheterization or suprapubic aspiration), white blood cell (WBC) count, C reactive protein (CRP), procalcitonin (PCT), and a blood culture. Additional tests, treatment and disposition decisions were made at the discretion of the treating provider.

The parents or caregivers of those infants managed as outpatients received a follow-up telephone call within 1 month after the initial visit at the PED to determine the course of the episode. The accuracy of the Step-by-Step approach, the Rochester criteria, and the Lab-score in identifying patients at low risk of IBI was compared.

Outcome

Of the 2185 infants included in the analysis, 504 were diagnosed with a bacterial infection (23.1%), including 87 patients (3.9%) with an IBI and 417 (19.1%) with a non-IBI. The first part of the algorithm (evaluating general appearance, age, and presence of leukocyturia) identified 79.3% of the IBI (including 22 of 26 patients with sepsis and 9 of 10 with bacterial meningitis) and 98.5% of the non-IBI.

After taking into account PCT, CRP, and ANC values, a subgroup of 991 low risk infants were identified (45.3% of the studied population) with a prevalence of IBI of 0.7%. The prevalence of potentially missed IBI was higher when using the Lab-score or the Rochester criteria than the Step by Step (p < .05). The prevalence of possible bacterial infection was similar in all the risk groups. Of the three approaches, the Step-by-Step approach demonstrated the best negative predictive value (NPV) of 99.3% and negative likelihood ratio of 0.17%. As expected, due to the relatively low prevalence of IBI (4.0%), the specificity, positive predictive value (PPV) and positive likelihood ratio were poor predictors of IBI in all three approaches.

Limitations

This study may not be entirely applicable to the US infant population due to the higher prevalence of IBI in Europe. In addition, the Rochester criteria performance was limited by the fact that the absolute band count was not available in all participating centers. Finally, this study compared the Step-By-Step approach to the Rochester criteria and the Lab Score which are not the most commonly used criteria in the evaluation of febrile infants under 90 days in the US.

The Bottom Line

The Step-by-step approach performed better than the Rochester criteria and the Lab Score in the identification of febrile infants ≤90 days at low risk for IBI. General appearance, age, and urine dipstick identified almost 80% of the IBI patients, 85% of the sepsis and 90% of the bacterial meningitis. Procalcitonin is a better biomarker to rule in an IBI, and, due its more rapid kinetic, is a more suitable biomarker in young infants who, for the great majority, present to the ED with a very early onset fever. This very short fever duration makes the evaluation of these patients even more challenging and highlights the important role of a short-term ED observation in the management of these patients.